GENERAL
CHEMISTRY 2
TABLE OF CONTENTS
Science Pocket Lesson 1
Kinetic Molecular Theory of Liquids and Solids
1
Science Pocket Lesson 2
Properties of Liquids
6
Science Pocket Lesson 3
Structure and Properties of Water
10
Science Pocket Lesson 4
Types and Properties of Solids
13
Science Pocket Lesson 5
The Temperature Curve and the Phase Changes of
Water and 𝐂𝐎𝟐
17
Science Pocket Lesson 6
Concentration of Solutions
22
Science Pocket Lesson 7
Stoichiometric Calculations for Reactions in Solutions
27
Science Pocket Lesson 8
Boiling Point Elevation and Freezing Point Depression
31
Science Pocket Lesson 9
Thermodynamics vs. Thermochemistry
35
Science Pocket Lesson 10
Science Pocket Lesson 11
Colligative Properties of Solutions
Rates of Reaction
39
43
Science Pocket Lesson 12
Molecular Collisions and the Orders of Reaction
47
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
KINETIC MOLECULAR THEORY
OF LIQUIDS AND SOLIDS
INSTANT TASK
Put all the items in the correct box according to their state of matter.
From the lists in Activity 1, fill up the table below and mark the
relationship to you of each.
Characteristic
Relatives
Grand
Parent
Aunt
/ Uncle
Cousin
Mother
or Father
Sibling
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
1
DIRECT TALK
Kinetic Molecular Theory of
Liquids and Solids
The
the properties
properties of
of gases
gases by
by assuming
assuming that
that gas
gas particles
particles act
act
The kinetic
kinetic molecular
molecular theory
theory explains
explains the
independently
very weak
weak attractive
attractive forces
forces between
between them,
them, the
the particles
particles are
are free
free totomove
moveabout
about
independently of
of each
each other.
other. Due
Due to
to the
the very
at
at random
random and
and fill
fill their
their containers.
containers. Gases
Gases are
are compressible
compressible and
and they
they diffuse
diffuse through
through one
one another
another easily.
easily.
The particles of a liquid are close together because of strong attractive forces between them. Like gas
particles, liquid particles also collide with each other and with the walls of their containers. However, since the particles
are close together, they can move only at short distances. This type of movement allows liquids to flow and take the
shape of their container without filling it completely as gases do. This also explains why liquids compress only very
slightly, have higher densities than gases, and diffuse more slowly than gases.
In solids, the attractive forces between the particles are stronger than those in liquids and gases. These result
to an ordered arrangement of particles in which the particles are not free to move around. The movement of the particles
is limited to vibrations while they remain in their fixed positions. Thus a solid has a fixed volume and shape. Solids
compress even less than liquids and hardly diffuse.
The three phases of matter. Notice that the spacing between atoms or molecules increases as we move from a
description of the solid phase to the gaseous one.
Intermolecular Forces
nnkh
Intermolecular forces (IMF) or (secondary forces) are the forces which intimidate the reaction between particles
between molecules, including forces of attraction or repulsion which act between atoms and other types of neighboring
particles, e.g. atoms or ions. Intermolecular forces are weak relative to intramolecular forces – the forces which hold a
molecule together. They are ion-dipole, dipole-dipole, dipole-induced dipole, and London dispersion forces. Another
more specific intermolecular forces that affects only certain kinds of molecules is the hydrogen bond.
Intermolecular Forces
2
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
Ion - Dipole Forces
An ion-dipole forces results when an ion and the partial charge
on the end of a polar molecule attract each other. Polar molecules are
dipoles, that is, they have a positive and a negative end. Positive ions are
all attracted to the negative end of a dipole, while negative ions are
attracted to the positive end. Ion-dipole forces are particularly important in
solutions of ionic substances such as NaCl in polar liquids such as water.
Dipole - Dipole Forces
Neutral polar molecules experience dipole-dipole forces. Polar molecules
attract each other when the positive end of one molecule is near the negative end
of another. A dipole-dipole force is generally weaker than an ion-dipole force.
The strength of a given dipole-dipole interaction depends on the sizes of the dipole
moments involved.
Comparison of Molecular Weights, Dipole Moments, and Boiling Points
Comparison of Molecular Weights, Dipole Moments, and Boiling Points
The more polar the substance, the
stronger
its
dipole-dipole
interactions. The higher the dipole
moment,
the
stronger
the
intermolecular forces that must be
overcome for a substance to boil,
and the higher the boiling point.
London - Dispersion
Forces
It is rather easy to understand intermolecular forces among charged and polar
particles, but it is not so among atoms or nonpolar molecules. Nonpolar molecules such
as Cl2 and CH4 exhibit attractive forces. These nonpolar substances can be condensed
to liquid and even solid if cooled enough to low temperature. The origin of this attraction
was explained in 1930 by Fritz London (1900-1954), a German-American physicist.
On the average, the electrons in a nonpolar molecule or atom are distributed uniformly around the nucleus.
However, at certain instances, the electrons may be on one side of the nucleus. The molecule becomes temporary dipole or
momentary dipole or instantaneous dipole. An instantaneous dipole exerts an influence on nearby particles. It causes the
distortion of the electron clouds of neighboring molecules. As a result, the neighboring molecules also become dipoles.
They are called induced dipoles because they are caused by the formation of the first dipole. This kind of attraction is called
instantaneous dipole-induced dipole attraction or London forces. They are short-lived attractions because electrons
keep on moving which causes the dipole to vanish as quickly as they are formed.
The ease with which a dipole can be induced is called polarizability. Polarizability increases with increased
molecular mass. In large molecules, the electrons are less firmly held and therefore easier to be polarized. As polarization
and London forces increase, the boiling and melting points of covalent substances generally increase with increasing
molecular mass.
.
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3
The ease with which a dipole can be
induced is called polarizability.
Polarizability increases with increased
molecular mass. In large molecules, the
electrons are less firmly held and
therefore easier to be polarized. As
polarization and London forces
increase, the boiling and melting points
of covalent substances generally
increase with increasing molecular
mass.
Molar Mass, Melting Points, and Boiling Points of Halogen
Hydrogen Bond
A hydrogen bond is an attractive interaction between a hydrogen atom bonded to an electronegative O, N, or F
atom and an unshared electron pair of another nearby electronegative atom. For example, hydrogen bonds occur in
water, ammonia, and hydrofluoric acid.
Hydrogen bond is a special type of dipole-dipole
interaction. Bonds between hydrogen and nitrogen,
oxygen, or fluorine are highly polar with partial positive
charge on the hydrogen and a partial negative charge
on the electronegative atom. In addition, the hydrogen
atom has no inner core electrons and almost a bare
proton. Thus, this small electron-deficient hydrogen can
approach an electronegative atom very closely and
interact strongly with it.
One of the consequences of hydrogen bond in
hydrogen compounds is the increase of boiling point
with increasing molecular weight due to increased
dispersion forces.
O, N, and F atoms have significant
hydrogen bonding ability because of
their electronegative values and small
atomic sizes. Chlorine has the same
electronegative value as nitrogen but
its size is larger, so it has less
hydrogen bonding ability.
The type of attraction used in life
processes that can easily be formed and
broken and reformed especially in water,
DNA, and proteins is the hydrogen bond.
4
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
FLASH CHECK
Identify the dominant intermolecular forces for the following
Identify the dominant intermolecular forces of the following substances.
higher boiling point in each
substances.
Select
the substance
theboiling
Select
the substance
with thewith
higher
point in each pair.
pair.
A. Ne and Ar
A. Ne and Ar
__________________________________________________________
____________________________________________________________________
____________________________________________________________________
B. CH3OH and CH3CH2OH
B. CH33OH and CH33CH22OH
_________________________________________________________
____________________________________________________________________
C. HF and CH F
3
3F
C. HF and CH3__________________________________________________________
____________________________________________________________________
____________________________________________________________________
D. BaCl2 and PCl3
D. BaCl22 and PCl
33
__________________________________________________________
_____________________________________________________________________
QUICK
CONNECT
You only have to think about water to
appreciate how different the three
states of matter are. Flying, swimming,
and ice skating are all done in contact
with water in its various states. We
swim in liquid water and skate on water
in its solid form (ice). Airplanes fly in an
atmosphere containing water in the
gaseous state (water vapor). To allow
these various activities, the
arrangements of the water molecules
must be significantly different in their
gas, liquid, and solid forms.
REFERENCES
• Breaking through chemistry pp. 313 - 323
• World of chemistry pp. 516 - 522
• https://www.liveworksheets.com/os987191op
• https://cscsdashaicechem.weebly.com/chapter4---chemical-bonding.html
• http://brainfuse.com/curriculumupload/12240578
98133.html
• https://chem.libretexts.org/Courses/University_of
_Arkansas_Little_Rock/Chem_1403%3A_Gener
al_Chemistry_2/Text/11%3A_Intermolecular_For
ces_and_Liquids/11.03%3A__DipoleDipole_Forces
• https://irpcdn.multiscreensite.com/89a70595/files/uploade
d/Liga%C3%A7%C3%B5es%20intermoleculares
_.pdf
• https://legacy.chemgym.net/environmental_chem
istry/topic_3c/page_4.html
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
5
GENERAL
PROPERTIES OF LIQUIDS
CHEMISTRY 2
INSTANT TASK
NOTE: There are
10 terms you need
to find.
Encircle the term that are related to the
properties of liquids
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SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
R
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DIRECT TALK
VISCOSITY
Viscosity can be
measured using a
viscometer. It
measures the time it
takes for a known
volume of a liquid to
flow through the
small neck.
Some liquids such as water or alcohol flow easily. They are fluid. Others such as
molasses or motor oil take longer time to flow (they are viscous). Viscosity is related to the
movement of the molecules in the liquid, and thus to the intermolecular forces present. Nonpolar
molecules like benzene (C6H6), pentane (C5H12), and carbon tetrachloride (CCl4) experience
only weak intermolecular forces (dispersion forces) and low viscosities. More polar molecules
like glycerol (C3H5C (OH)3) and aqueous sugar solution (syrup) have high viscosities because
of H-bonding among many -OH groups and dispersion forces at many points along the chain.
The viscosity of a liquid decreases with increasing temperature because at higher
temperatures, the average kinetic energy of the molecules that overcomes the attractive forces
between molecules is greater.
SURFACE TENSION
TAKE
NOTE
To increase the surface area, molecules move to the surface by
breaking some attractions in the interior, which requires energy. The energy
required to increase the surface area of a liquid is called surface tension.
Surface tension, like viscosity, is higher in liquids that have higher
intermolecular forces. Both properties are also temperature dependent because
at higher temperatures, molecules have more kinetic energy to counteract the
attractive forces holding them. Surfactants (surface-active agents) such as
detergents, soaps, and biological fat emulsifiers decrease the surface
tension of water and destroy the H-bonds.
CAPILLARITY
When you go for
simple blood tests, a
sample may be
obtained by pricking
your finger with a
needle. A narrow
tube called capillary
tube is placed on
the skin opening
and the blood rises
up through the tube.
This phenomenon is called capillarity or capillary action. This results from a
competition between the intermolecular forces within the liquid molecules (cohesive forces) and
those between the liquid molecules and the walls of the tube (adhesive forces).
When a capillary tube is placed in water, the surface or meniscus takes a U-shape
(concave) because the adhesive forces are greater than cohesive forces. In mercury, the
meniscus is curved downward (convex) because the cohesive forces (metallic bonding are
stronger than adhesive forces.
Capillarity is also observed in the transport of water from the roots to the other parts of
plants.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
7
VAPOR PRESSURE
The vapor pressure of a liquid depends on the magnitude of
the intermolecular forces present and on temperature. Liquids like
acetone and alcohol have high vapor pressure and are considered
volatile because their intermolecular forces are weak; whereas molasses
and honey have low vapor pressures and are said to be nonvolatile. The
volatility of a liquid at a given temperature is determined by its
intermolecular forces of attraction.
BOILING POINT
The temperature at which boiling point occurs at a pressure of 1 atm is called the
normal boiling point of the liquid. This property changes as pressure changes. If the
atmospheric pressure is below 1 atm, especially at high altitudes like in Baguio City, liquids
boil at lower than normal temperatures. At an altitude of 1600 m, atmospheric pressure is
about 640 torr and water boils at 95 0C. This is because particles in the liquid need less
kinetic energy to escape. Cooking under these conditions takes longer than at sea level. The
effect of high altitudes and lower boiling temperature can be counteracted by using a
pressure cooker. In a pressure cooker, water boils at higher temperature and higher
pressure. The increased heat content of the boiling water allows the food to absorb heat from
the water faster than at 100 0C. A rise of about to 10 0C inside a pressure cooker cooks food
twice as fast as in 100 0C.
MOLAR HEAT OF VAPORIZATION
Vaporization is a change of state from liquid to gas. In order
for a liquid to change into a gas, energy must be added to the liquid.
This is an endothermic process and the total kinetic energy of the
substance increases. Energy added is in the form of heat. The amount
of heat needed to vaporize a given amount of liquid at its boiling point
is called heat of vaporization.
8
TAKE
NOTE
Refrigerators operate by using
refrigerant (Freon or ammonia)
which evaporates in the coils inside
the refrigerator. Evaporation is an
endothermic process that absorbs
heat inside the refrigerator. The
compressor recondenses the gas
back to liquid releasing heat through
the coils outside of the refrigerator.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
FLASH CHECK
4
Identify
the why
dominant
forces
for the following
Explain
eachintermolecular
of the following
occurs:
substances. Select the substance with the higher boiling point in each
pair.
1. A freely falling drop of water is spherical in shape.
A. Ne and Ar
__________________________________________________________________________________
__________________________________________________________________________________
____________________________________________________________________
____________________________________________________________________
__________________________________________________________________________________
B. CHarm
33OH and CH33CH22OH
2. Your
feels cool when alcohol evaporates from your skin.
____________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
C. HF and CH33F
__________________________________________________________________________________
____________________________________________________________________
____________________________________________________________________
3. On a warm day, water droplets form outside the bottle of carbonated beverage.
D. BaCl22 and PCl33
__________________________________________________________________________________
__________________________________________________________________________________
_____________________________________________________________________
__________________________________________________________________________________
QUICK
CONNECT
The hair on a gecko's foot are so tiny
that it can form intermolecular forces
of attraction with most surfaces and
thus making the gecko adhere even
on glass without the use of liquids or
surface tension.
REFERENCES
• Breaking through chemistry pp. 323 - 328
• World of chemistry pp. 516 - 522
• Pin by Nitza I Marin on DYK? | Did you know,
Surface tension, Fun facts (pinterest.ph)
• Learn Boiling vs Evaporation in 3 minutes.
(toppr.com)
• Surfact Active Agents, Surfactants (ncsu.edu)
• Chapter 13 Solids and Liquids. - ppt video online
download (slideplayer.com)
• a steel needle floating on water to illustrate
surface tension Stock Photo - Alamy
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
9
GENERAL
STRUCTURE AND PROPERTIES OF
CHEMISTRY 2
WATER
INSTANT TASK
S
WATER
SOLID
LIQUID
GAS
SHAPE
FREEZING POINT
BOILING POINT
Complete the diagram about the concept of water by writting the correct terms
from the box.
I N T E R M O L E C U L A R R
1. A clear, odorless
O N B P O M liquid
B that H
Q I C U S
has no R
taste. O
M O O E M Q O M U C Y Q K E D
O I I Y E H H H T O M U N R E
L S L U R3. TheEtemperature
T T A
M T I I U C
2. The temperature
8. A hard substance
9. A free flowing
I E Sat which
A a Vliquid J R
Jsubstance.
S R
atAwhichN a liquid
that P
has N
three D
turns into a solid.
boils.
R E N T A T I I dimensions.
E O G S N S E
E T G4. AnFobjectGform H S L S U H G I E A
O E Por figure.
R B G C N M C 10.
X A Ssubstance
H R S
such as air that is
U C O G C M O A E D not
O solidTor liquid.
D P L
5. A ___ has and keeps
6. A ___ borrows the
S shape.
A I S E shape
Rof itsScontainer.
P T S F S S R I
its own
R F N N W I I S F S E C R O F
C R T7. A ___Bhas noLfixedR T I Q B V C Q P U
shape.
N U X O D B Y S Z C Z X B A Y
I S N O I T A Z I R Note:
O Answers
P A mayVbe D
repeated
10
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
DIRECT TALK
Water makes up a large proportion of the entire biosphere and
of these, 95 % is saltwater and the remaining 5 % is freshwater. Water
is locked up in ice and glaciers, deep and shallow underground lakes,
soil, atmosphere, and in the rivers. The human body consist of 50-75%
water. Water serves important purposes for life on earth. Water's unique
properties result from the strong intermolecular forces of attraction
characterized by the hydrogen bond. The following are the properties of
water.
1. High boiling point
The high boiling point of water is a
consequence of its strong intermolecular forces of
attraction caused by the formation of the H-bond. It also,
explains why water is liquid at room temperature.
3. High density in its liquid form
Water is the only substance that contracts
when cooled. For most substances, their solid form is
denser than their liquid form. This is because the Hbond is more extensive in its solid state (ice) than in
its liquid state. Ice has an open structure because the
hydrogen bonds could not get inside the hexagonal
ring structure.
2. High specific heat
Specific heat refers to the amount of heat needed to
change the temperature of 1 gram of a substance by
1 0C. For water, its specific heat is 1cal/g 0C. It
means that water can absorb and release large
quantities of heat without change in temperature.
This is the reason why body temperature remains
370C even when there's a change in the surrounding.
This also explains why oceans and lakes exert an
influence on the climate. If there were no longer
bodies of water that surround the earth, the earth
would experience great temperature variations.
4. High surface tension
The hydrogen bond formation among water
molecules causes water to have high surface tension,
as described earlier. This high surface tension causes
water to move from the roots of a tree to the top of
very tall trees and explains why water moves into the
fibers of a towel. This phenomenon is called
capillarity.
5. High heat of vaporization
Large amount of heat is needed to vaporize a given amount of water. This
causes a significant drop in temperature during evaporation. This explains why
perspiration lowers the body temperature.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
11
FLASH CHECK
Identify the dominant intermolecular forces for the following
EXPLAIN BRIEFLY
substances. Select the substance with the higher boiling point in each
pair.
A.
Ar
If Ne
iceand
were
denser than liquid water, how would this affect the
____________________________________________________________________
environment we live in?
____________________________________________________________________
__________________________________________________________________________________
B. CH33OH and CH33CH22OH
__________________________________________________________________________________
____________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
C. HF and CH33F
__________________________________________________________________________________
__________________________________________________________________________________
____________________________________________________________________
____________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
D. BaCl22 and PCl33
__________________________________________________________________________________
_____________________________________________________________________
QUICK
CONNECT
12
REFERENCES
• General Chemistry 2 pp. 12 - 14
• https://www.pinterest.com.au/pin/657244139356
993388/
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
TYPES AND PROPERTIES OF
SOLIDS
INSTANT TASK
Complete the diagram about the classifications of solids by arranging the
terms from the box.
Metallic
Crystalline
Molecular
Hydrogen bond
Ionic
Polar
Amorphous
Non-polar
Covalent
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
13
DIRECT TALK
The Nature of Solids
Solids whose particles are arranged in regular geometric patterns are called crystalline solids. The representative
particles exist in a high ordered and repetitive pattern. This orderly arrangement produces a beautiful regularly shaped
crystal. NaCl and sugar are crystalline in form and so is snow. Many precious stones used in jewelry are crystals.
Crystalline Solids
Crystalline solids are those whose atoms, ions,
or molecules are ordered in well-defined arrangements.
They usually have flat surfaces or faces and sharp
angles. These solids have regular shapes. Ice, sugar,
salt, and gems are examples of crystalline solids.
Amorphous Solids
Amorphous solids (from the Greek word for
"without form") are solids whose particles do not have
orderly structures; therefore, they have poorly defined
shapes. Some examples of amorphous solids are glass,
rubber, and some plastics.
TAKE
NOTE
Crystalline solids have particles that are arranged in a definite geometric pattern.
Amorphous solids have particles that are not located in any particular position.
14
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
TYPES OF CRYSTALS
The physical properties of solids depend on the kind of particles that make up the solid. They are also
dependent on the strength of the attractive forces between the particles. Solids are classified based on the
kind or nature of the particles that make them up.
For the melting and boiling points, it is important to note that the energy required is that needed to break
the intermolecular forces of attraction and not the intramolecular.
A. IONIC SOLIDS
The particles of ionic solids are positive and negative ions. Since
oppositely charged particles are present, the forces between the ions are
electrostatic in nature. The crystal arrangement in ionic solids maximizes
attractions and simultaneously minimizes repulsion making the compound
possess a high degree of stability. These solids are hard, they are brittle, have
high melting points, and have poor electrical and thermal conductivity.
B. COVALENT SOLIDS
This type of solids are made up of atoms and are joined by covalent
bonds. Some solids form covalent bonds resulting in the formation of
molecules. In some solids, however, molecules are not formed. Rather, a
covalent network is formed extending throughout the solid crystal. They are
very hard, have very high melting points, and often have poor thermal and
electrical conductivity.
C. MOLECULAR SOLIDS
The particles in molecular solids can be either atoms or molecules held
together by intermolecular forces like dispersion forces, dipole-dipole forces,
and hydrogen bonds. Solids with dispersion forces that are also large are solids
at room temperature. This is true for solids that are highly polar. This type of
solids are soft, have low to moderately high melting points, and have poor
electrical and thermal conductivity. They are poor conductors of heat and
electricity because there are no free moving electrons and no charge particles.
D. METALLIC SOLIDS
These are joined by metallic bonds. Metallic bonds are characterized
by the presence of mobile electrons around the positive metal ion. The force
that binds the atoms together is the force attraction between the mobile
valence electrons and the fixed positive metal ion. The strength of the force
depends on the metal and, depending on the nature of the metal, they can be
soft to hard, and melting points range from low to high. These solids are good
electrical conductors (because of the mobile electrons), good thermal
conductors, and are malleable and ductile.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
15
FLASH CHECK
4
Identify the dominant intermolecular forces for the following
EXPLAIN BRIEFLY
substances. Select the substance with the higher boiling point in each
pair.
Suppose you are a molecule of water in the solid state (ice) at -10 0C. Write a short
A. description
Ne and Ar of your movement as the temperature around you is gradually and
continuously increased to 110 0C.
____________________________________________________________________
____________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
B. CH33OH and CH33CH22OH
__________________________________________________________________________________
____________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
C. HF and CH33F
__________________________________________________________________________________
__________________________________________________________________________________
____________________________________________________________________
____________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
D. BaCl22 and PCl33
__________________________________________________________________________________
_____________________________________________________________________
__________________________________________________________________________________
QUICK
CONNECT
Quartz glass forms from silica
(SiO2) heated above 1600 0C. It
then evolves to form amorphous
solids like window glass (with
CaCO3 and Na2CO3), colored glass
(with metal ions), and barosilicate
glass in pyrex (B2O3).
16
REFERENCES
• Breaking through chemistry pp. 330 - 332
• General Chemistry 2 pp. 14 - 17
• E School (apsacwestridge.edu.pk)
• Classification of solids (brainkart.com)
• Crystalline Solids | Crystalline solid, Solid,
Intermolecular force (pinterest.ph)
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
The Temperature Curve and
The Phase Changes of Water and CO2
INSTANT TASK
The diagram below shows the cooling curve for a gas. Draw the diagram and
write/draw the correct word/figure in each number.
A
B
C
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
17
Heating and Cooling Curves Explained
What happens when you let a glass of ice sit out on the counter for several
minutes? It melts, of course! The increase in temperature causes the water to
change from solid to liquid.
What happens when you pour that cup of water into a pot
on the stove and let it cook for several minutes? It boils! Once
again, the increase in temperature causes the water to change
phases, this time from a liquid state to a gaseous state.
In the science world, we use heating and cooling curves to model such physical changes. A
heating or cooling curve is a simple line graph that shows the phase changes a given substance
undergoes with increasing or decreasing temperature.
T
E
M
P
E
R
A
T
U
R
E
HEAT ADDED
Fig. 1.1 Heating and Cooling Curve of Water. Temperature is
measured on the vertical y-axis and the amount of heat added over
time is measured on the horizontal x-axis. Changes of state occur
during plateaus because the temperature is constant.
The change of state behavior of all substances can be represented with a heating and cooling
curve of this type. The melting, boiling, freezing, and condensing points of the substance can be
determined by the horizontal lines or plateaus on the curve.
Phase changes happen when you reach certain special points. Sometimes a liquid wants to
become a solid. Scientists use something called a freezing point or melting point to measure the
temperature at which a liquid turn into a solid.
Melting - or Fusion, is a physical process that results in
the phase transition of a substance from a solid to a
liquid. This occurs when the internal energy of the solid
increases,
Freezing – The opposite of Melting. The process
through which a substance changes from a liquid to
a solid.
18
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
Boiling - is the process by which a liquid turn into a vapor when it is heated to its boiling point.
Condensation - is the process of a substance that is in its gaseous state converting into a
liquid state. This change is brought about by a change in pressure and temperature of the
substance.
Sublimation - refers to the phase transition in which matter changes state from a solid
immediately into a gas, without passing through an intermediate liquid phase.
Deposition - refers to the phase transition in which matter changes state from a gas
immediately into a solid, without passing through an intermediate liquid phase.
PHASE DIAGRAMS OF WATER AND CARBON DIOXIDE
We can use the phase diagram of
water to identify the physical state of a
sample of water under specified conditions of
pressure and temperature. For example, a
pressure of 50 kPa and a temperature of
−10 °C correspond to the region of the
diagram
labeled
“ice.”
Under
these
conditions, water exists only as a solid (ice). A
pressure of 50 kPa and a temperature of 50
°C correspond to the “water” region—here,
water exists only as a liquid. At 25 kPa and
200 °C, water exists only in the “gas” or in
gaseous state. Note that on the H2O phase
diagram, the pressure and temperature axes
not drawn to a constant scale in order to permit the illustration of several important features as
are not
described here.
The curve BC in the figure above is the plot of
vapor pressure versus temperature. This “liquid-vapor”
curve separates the liquid and gaseous regions of the
phase diagram and provides the boiling point for water at
any pressure. The solid-vapor curve, labeled AB in the
graph above indicates the temperatures and pressures at
which ice and water vapor are in equilibrium. These
temperature-pressure data pairs correspond to the
sublimation, or deposition, points for water. The solidliquid curve labeled BD shows the temperatures and
pressures at which ice and liquid water are in equilibrium,
representing the melting/freezing points for water.
Example: Determining the State of Water
Using the phase diagram for water given in the graph, determine the state of water at the
following temperatures and pressures:
(a) 50 °C and 40 kPa
(b) 80 °C and 5 kPa
(c) −10 °C and 0.3 kPa
Solution: Using the phase diagram for water, we can determine that the state of water at
each temperature and pressure given are as follows: (a) liquid; (b) gas; (c) solid.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
19
You already know about solids melting and becoming liquids. Some of you may have also seen
a solid become a gas. It's a process called sublimation. The easiest example of sublimation
might be dry ice. Dry ice is solid carbon dioxide (CO2). Amazingly, when you leave dry ice
out in a room, it just turns into a gas. Have you ever heard of liquid carbon dioxide? It can be
made, but not in normal situations. Coal is another example of a compound that will not melt
at normal atmospheric pressures. It will sublimate at very high temperatures.
Can you go from a gas to a solid? Sure. Deposition occurs when a gas
without going through the liquid state of matter. Those of you who live near
not have seen it, but closer to the poles we see frost on winter mornings.
crystals on plants build up when water vapor from the air becomes a solid
plants.
becomes a solid
the equator may
Those little frost
on the leaves of
Consider the phase diagram for carbon dioxide shown in the figure as another example. The
solid-liquid curve exhibits a positive slope, indicating that the melting point for CO2 increases with
pressure as it does for most substances (water being a notable exception as described previously).
Notice that the triple point is well above 1 atm (101.325 kPa), indicating that carbon dioxide cannot
exist as a liquid under ambient pressure conditions. Instead, cooling gaseous carbon dioxide at 1
atm results in its deposition into the solid state. Likewise, solid carbon dioxide does not melt at 1
atm pressure but instead sublimes to yield gaseous CO2. Finally, notice that the critical point for
carbon dioxide is observed at a relatively modest temperature and pressure in comparison to water.
Example: Determining the State of Carbon Dioxide
Using the phase diagram for carbon dioxide shown in the graph, determine the state of CO2 at
the following temperatures and pressures:
(a) −30 °C and 2000 kPa (b) −90 °C and 1000 kPa (c) −60 °C and 100 kPa
Solution: Using the phase diagram for carbon dioxide provided, we can determine that the
state of CO2 at each temperature and pressure given are as follows: (a) liquid; (b) solid; (c)
gas.
20
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
Instructions: Answer the following questions. Write your answer in a separate sheet of
paper.
Using the phase diagram for water, determine the state of water at the following
temperatures and pressures:
(a) −10 °C and 50 kPa
(b) 25 °C and 90 kPa
(c) 50 °C and 0.3 kPa
Using the phase diagram for carbon dioxide, determine the state of water at the following
temperatures and pressures:
(d) 20 °C and 1500 kPa
Answer to
START-UP
(e) 0 °C and 100 kPa
(f) 20 °C and 2 atm
The steamboats got their power from steam – liquid water converted to a gas at
high temperatures. The steam would push the pistons of the engine, causing the
paddle wheels to turn and propel the boat.
References:
QUICK
CONNECT
Gases under Pressure
If you have a propane (C3H8)
barbecue, you have probably seen
those cylinders filled with fuel. In
the
cylinder,
the
propane
molecules are in a liquid state at a
high
pressure.
When
the
molecules are released from the
cylinder, they immediately become
a gas and you can cook your food.
Pressure differences make the
phase change.
•
•
•
•
•
http://www.chem4kids.com/
https://study.com/academy/le
sson
https://www.ck12.org/
https://opentextbc.ca/
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
21
GENERAL
CHEMISTRY 2
Concentration of Solutions
INSTANT TASK
MATH SKILL BUILDER 101
Percent =
Part
Whole
x 100%
Solve the following problems. Write your solutions in a separate sheet of paper.
1.) There are 200 apples. 30 apples are considered bad and will be not for sale. How
many percent of apples are bad?
2.) What percentage of 80 is 20?
3.) A skateboard is on sale that has a 25% discount of its price. The skateboard’s
original price is Php 750.00. Find the new price.
22
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
The
key
difference
between
solvent
and
solute is that the solute is
the one to be dissolved
while, the solvent is
responsible for dissolving
it.
Fig. 1: The solution on the left is more
concentrated than the solution on the
right because there is a greater ratio of
solute (red balls) to solvent (blue balls)
particles. The solution particles are closer
together. The solution on the right is more
dilute (less concentrated).
Concentration is the measure of how much of a given
substance is mixed with another substance. Solutions are said to
be either dilute or concentrated. When we say that vinegar is 5%
acetic acid in water, we are giving the concentration. If we said
the mixture was 10% acetic acid, this would be more
concentrated than the vinegar solution.
A concentrated solution is one in which there is a large
amount of solute in a given amount of solvent. A dilute solution
is one in which there is a small amount of solute in a given
amount of solvent. A dilute solution is a concentrated solution
that has been, in essence, watered down. Think of the frozen
juice containers you buy in the grocery store. To make juice, you
have to mix the frozen juice concentrate from inside these
containers with three or four times the container size full of
water. Therefore, you are diluting the concentrated juice. In
terms of solute and solvent, the concentrated solution has a lot of
solute versus the dilute solution that would have a smaller
amount of solute. Therefore: Concentration of a solution is the
mass or volume of the solute present in a given amount of
solvent or solution.
The Ways of Expressing Concentration of a Solution
Another way of expressing concentration is to give the number of
moles of solute per unit volume of solution. Of all the quantitative
measures of concentration, molarity is the one used most frequently by
chemists. Molarity is defined as the number of moles of solute per liter of
solution.
The symbol for molarity is M or moles/liter. It is
important to remember that “mol” in this expression refers to
moles of solute and that “L” refers to liters of solution.
number of moles of solute
Molarity =
number of liters of solution
Example: What is the molar concentration of a solution of 22.4 g of HCl dissolved in 1.56 L?
STEP 1 Find the molar mass of HCl.
Hydrochloric Acid = HCl = 1 H atom + 1 C atom
Atomic Mass of H = 1 x 1.008 g/mol = 1.008 g
Atomic Mass of Cl = 1 x 35.453 g/mol = 35.453 g (add)
Molar Mass of HCl = 36.453 g
STEP 2 Convert the mass of solute to moles using
the molar mass of HCl.
22.4 g HCl x
1 mol HCl
36.5 g HCl
= 0.614 mol HCl
STEP 3 Now, we can use the definition of
molarity to determine a concentration.
0.614 mol HCl
1.56 L solution
= 0.394 M HCl
M =
*Remember! If the quantity of the solute is given in mass units, you must convert mass units to
mole units before using the definition of molarity to calculate concentration.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
23
There are several ways of expressing the concentration of a solution using a percentage. The
mass/mass percent (% m/m) is defined as the mass of a solute divided by the mass of a solution times 100:
% m/m =
mass of solute
mass of solution
*Remember! If you can measure the masses of the
solute and the solution, determining the mass/mass
percent is easy. Each mass must be expressed in the
same units to determine the proper concentration.
X 100%
Where: mass of solution = mass of solute + mass of solvent
Example: Suppose that a solution was prepared by dissolving 25.0g of sugar into 100.0g
of water. Determine the concentration.
STEP 1 Find the mass of the solution.
mass of solution = 25.0 g sugar + 100.0 g water = 125.0 g
STEP 2 Calculate the percent by mass.
Percent by Mass =
25.0 g sugar
125.0 g solution
X 100% = 20% sugar
Related concentration units are parts per million (ppm).
Example: If there is 0.551 mg of As in 348 g of solution, what is the As concentration in
ppm?
STEP 1 Convert 0.551 mg to grams.
STEP 2 Determine the concentration.
0.551 mg x
0.000551 g
348 g
1 gram
1000 mg
= 0.000551 g
x 1,000,000 = 1.58 ppm
The percent solutions can be in the form volume/volume percentage. In each case, the concentration
in percentage is calculated as the fraction of the volume of the solute related to the total volume of the
solution.
Volume Percent =
volume of solute
x 100%
volume of solution
Example: Determine the volume/volume percent solution made by combining 25 mL of
ethanol with enough water to produce 200 mL of the solution.
STEP 1 Substitute the values in the given formula.
Volume Percent =
25 mL
200 mL
x 100%
= 12.5%
Molality is also known as molal concentration. It is a
measure of solute concentration in a solution. The solution is
composed of two components; solute and solvent.
Molality is defined as the “total moles of a solute contained in a
kilogram of a solvent.”
24
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
m=
Number of moles of solute
Mass of solvent in kilograms
Difference between Molality and Molarity
Example: Calculate the molality of a solution where 5.0 grams of toluene (C7H8) is
dissolved in 225 grams of Benzene (C6H6). Calculate the moles of given solute.
STEP 1 Find the molar mass of Toluene.
STEP 2 Find the moles of Toluene.
STEP 3 Calculate the kilogram of solvent.
STEP 4 Calculate the molality.
C7H8 = (7 x 12 g/mol) + (8 x 1.008 g/mol) = 92 g/mol
Moles of Toluene =
Mass in grams
Molar mass
=
5.0 g
92 g/mol
= 0.054 mole
225 g of Benzene / 1000 = 0.225 kilograms
m=
Number of moles of Toluene
Mass of Benzene in kgs
=
0.054 moles
0.225 kg
= 0.24 m
Mole fraction is a unit of concentration, defined to be equal to the number of moles of a component
divided by the total number of moles of a solution. Because it is a ratio, mole fraction is a unitless
expression. The mole fraction of all components of a solution, when added together, will equal 1.
Example: In a solution of 1 mol benzene, 2 mol carbon tetrachloride, and 7 mol acetone,
the mole fraction of the acetone is ______.
STEP 1 Find the total number of moles in the solution
Total number of Moles in Solution = 1 mole (benzene) + 2 moles (carbon tetrachloride) + 7 moles (acetone)
Total number of Moles in Solution = 10 moles
STEP 2 Apply the Mole Fraction formula of a substance (shown
below)
Mole Fraction of Acetone = Moles of Acetone / Total Moles Solution
Mole Fraction of Acetone = 7/10
Mole Fraction of Acetone = 0.7
Similarly, the mole fraction of benzene would be 1/10 or 0.1 and the mole fraction of carbon
tetrachloride would be 2/10 or 0.2.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
25
Instructions: Perform the different ways of calculating the concentrations of solutions.
Write your answer in a separate sheet of paper.
a. Calculate the molarity of 0.000889 g of glycine, C2H5NO2, in 1.05 mL of
solution.
1.
b. A saline solution with a mass of 355 g has 36.5 g of NaCl dissolved in it.
What is the mass/mass percent concentration of the solution?
c. If there is 0.6 g of Pb present in 277 g of solution, what is the Pb
concentration in parts per million?
f. A solution is prepared by dissolving 90 mL of hydrogen peroxide in
enough water to make 3000 mL of solution. Identify the concentration
of the hydrogen peroxide solution through volume/volume percentage.
e. Calculate the molarity of 25.0 grams of KBr dissolved in 750.0 mL pure
water. (K = 40 g/mol; Br = 80 g/mol)
d. The solution is prepared by mixing 25.0 grams of ethanol and 25.0
grams of water. Determine the mole fractions of ethanol. (The molecular
weight of ethanol = 46.07 g/mol; water = 18 g/mol)
Answer to
START-UP
By looking at percentages, it is easier to tell if one recipe is drier, sweeter, saltier,
etc. than another recipe. It also makes predicting what the final product will look
like easier. Baker’s % can be used to quickly and easily convert between batch
sizes as well.
QUICK
CONNECT
Anyone who has made instant coffee
or lemonade knows that too much
powder gives a strongly flavored,
highly concentrated drink, whereas
too little results in a dilute solution
that may be hard to distinguish from
water.
In
chemistry,
the
concentration of a solution is the
quantity of a solute that is contained
in a particular quantity of solvent or
solution. Knowing the concentration
of solutes is important in controlling
the stoichiometry of reactants for
solution reactions.
26
References:
•
•
•
•
https://chem.libretexts.org/
https://byjus.com/
https://www.thoughtco.com/
https://byjus.com/
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
Stoichiometric Calculations for
Reactions in Solutions
INSTANT TASK
Let us bake cookies! If we will make 10 cookies, the exact number
of ingredients are as follows:
200 grams of flour + 2 eggs + 200 grams of butter + 1 cup of sugar = 10 cookies
But it turns out that the ingredients are incomplete because you only have one (1)
egg. A new equation is made, where everything is cut in half to achieve a result:
___grams of flour + 1 egg + ___grams of butter + ___cup of sugar = ___cookies
1. Fill in the blanks the right amount of ingredients and the cookies to be made
with just one egg.
2. Airbags inside a car contains sodium azide. Write the
coefficients so that the chemical equation below will be
balanced.
___NaN3 → __Na + __N2
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27
Introduction to Stoichiometry
A balanced chemical equation is analogous to a recipe for
chocolate chip cookies. It shows what reactants (the ingredients)
combine to form what products (the cookies). It also shows the
numerical relationships between the reactants and products (such
as how many cups of flour are required to make a single batch of
cookies).
These numerical relationships are known as reaction stoichiometry, a term derived from the
Ancient Greek words stoicheion ("element") and metron ("measure"). In this lesson, we'll look at how
we can use the stoichiometric relationships contained in balanced chemical equations to determine
amounts of substances consumed and produced in chemical reactions.
Balanced Equations and Mole Ratios
A common type of stoichiometric relationship is the mole ratio, which relates the amounts in
moles of any two substances in a chemical reaction. We can write a mole ratio for a pair of substances
by looking at the coefficients in front of each species in the balanced chemical equation. For example,
consider the equation for the reaction between iron(III) oxide (Fe2O3) and aluminum metal (Al):
The coefficients in the equation tell us that 1 mole of Fe2O3 reacts with 2 moles of Al, forming 2
moles of Fe and 1 mole of Al2O3. We can write the relationship between the Fe2O3 and the Al as the
following mole ratio:
Using this ratio, we could calculate how many moles of Al are needed to fully react with a
certain amount of Fe2O3, or vice versa. To illustrate, let's walk through an example where we use a
mole ratio to convert between amounts of reactants.
Using mole ratios to calculate mass of a reactant
Consider the following unbalanced equation:
O
3
reactant side
product side
Question: How many grams of NaOH are required to fully consume 3.10 grams of H 2SO4?
start text, F, e, end text, start subscript, 2, end subscript, start text, O, end text, start
first:orwe
need
to balance the equation! In this case, we have 1 Na atom and
subscript, 3,First
endthings
subscript,
vice
versa.
3 H atoms on the reactant side, and 2 Na atoms and 2 H atoms on the product side. We can
balance the equation by placing a 2 in front of NaOH (so there are 2 Na atoms on each side)
and another 2 in front of H2O (so that there are 6 O atoms and 4 H atoms on each side.) Doing
so gives the following balanced equation:
Now that we have the balanced equation, let's get to problem solving. To review, we
want to find the mass of NaOH that is needed to completely react 3.10 grams of H2SO4. We
can tackle this stoichiometry problem using the following steps: (See next page)
28
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
Step 1: Convert known reactant mass to moles
In order to relate the amounts H2SO4 and NaOH using a mole ratio, we first need
to know the quantity of H2SO4 in moles. We can convert the 3.10 grams of H2SO4 to
moles using the molar mass of H2SO4.
H2SO4= 2 H atoms + 1 S atom + 4 O atoms
Atomic Mass of H = 2 x 1.008 g/mol = 2.016 g/mol
Atomic Mass of S = 1 x 32 g/mol = 32 g/mol
Atomic Mass of O = 4 x 16 g/mol = 64 g/mol (add)
Molar Mass of H2SO4 = 98.02 g/mol
Proceed to conversion of 3.10 grams of H2SO4 to moles:
Step 2: Use the mole ratio to find moles of other reactant
Now that we have the quantity of H2SO4 in moles, let's convert from moles of
H2SO4 to moles of NaOH using the appropriate mole ratio. According to coefficients in
the balanced chemical equation, 2 moles of NaOH are required for every 1 mole of
H2SO4, so the mole ratio is:
Multiplying the number of moles of H2SO4 by this factor gives us the number of
moles of NaOH needed:
Notice how we wrote the mole ratio so that the moles of H2SO4 cancel out,
resulting in moles of NaOH as the final units.
Step 3: Convert moles of other reactant to mass
We were asked for the mass of NaOH in grams, so our last step is to convert the
6.32 x 10-2 moles of NaOH to grams. We can do so using the molar mass of NaOH:
Molar Mass of NaOH = (1 x 23 g/mol) + (1 x 16 g/mol) + (1 x 1.008 g/mol) = 40 g/ mol
So, 2.53 grams of NaOH are required to fully consume 3.10 grams of
H2SO4 in this reaction.
Shortcut! We could have combined all three steps into a single calculation, as shown in the
following expression:
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
29
Instructions: Solve the problem stated below. Write your solution in a separate sheet
of paper.
Propane (C3H8) burns in this reaction:
Question: If 200 g of propane is burned, how many grams of H2O is produced?
Answer to
START-UP
With stoichiometry, you can know how much nitrogen gas must be produced in a
matter of seconds for the bag to inflate by impact and can save the life of the
driver or passengers.
References:
QUICK
CONNECT
Stoichiometry is at the heart of the
production of many things you use
in your daily life. Soap, tires,
fertilizer, gasoline, deodorant, and
chocolate bars are just a few
commodities you use that are
chemically
engineered,
or
produced
through
chemical
reactions. Chemically engineered
commodities
all
rely
on
stoichiometry for their production.
30
1.
2.
3.
4.
http://www.chem4kids.com/
https://study.com/academy/le
sson
https://www.ck12.org/
https://opentextbc.ca/
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
BOILING POINT ELEVATION AND
CHEMISTRY 2
FREEZING POINT DEPRESSION
INSTANT TASK
Unscramble the letters to form the term that describes the given phrase. Write the
letters on the blanks provided.
1.
L O N G B I I
T I P N O
__ __ __ __ __ __ __
__ __ __ __ __
➢ The ________________ of a substance is the temperature at which
the vapor pressure of a liquid equals the pressure surrounding the
liquid and the liquid changes into a vapor.
2.
R I N G Z E E F
O T N I P
__ __ __ __ __ __ __ __
__ __ __ __ __
➢ The ________________ is lower than the melting point in the case of
mixtures and for certain organic compounds such as fats.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
31
DIRECT TALK
BOILING POINT ELEVATION
The boiling point is the temperature at which the vapor pressure of a liquid is equal to the atmospheric
pressure. If a liquid has a high vapor pressure it means that the molecules evaporate faster, and it takes a shorter time
to equalize the vapor pressure of the liquid and the atmospheric pressure. Therefore, the boiling point of the liquid is
low. The boiling point of water is 100 0C. Sea water, however, does not boil at this temperature but at a higher
temperature. In the same manner, the burn caused by boiling point of syrup is higher than that of pure water. This is
because the interaction of the solute-solvent in a solution is greater than the interaction of solvent-solvent in pure
solvent or solute-solute in a pure solute. Since the vapor pressure is lower in solutions, it takes a longer time to
equalize the vapor pressure of the liquid and the atmospheric pressure. Thus, it takes a higher temperature to attain
the boiling point of a solution. The boiling point of a solution, therefore; is greater than the boiling point of a pure
solvent.
The boiling point elevation of a solution, ΔTb, is directly proportional to the number of solute particles. For
dilute solutions, ΔTb is proportional to molality, that is, ΔTb = Kb x m
Where K is the molal boiling point elevation constant of the solvent and m is the molal concentration
of the solution.
The K of water is 0.52 0C/m, so 1 m aqueous
solution of a nonvolatile solute like sucrose will boil at
0.52 0C higher than pure water. The boiling point
elevation is proportional to the number of solute particles
in the solution. When 1 mole of NaCl dissolves in water,
2 moles of solute are formed 1 mole of Na and 1 mole
Cl. Therefore, a 1 m solution of NaCl in water causes a
boiling point elevation twice as large as a 1 m solution of
sucrose.
Example
Molal Boiling Point Constant
Calculate the boiling point of a solution containing 3.5 g sugar (molar mass = 342 g)
dissolved in 150 g of water. The mass of solute (3.5 g) is given which is dissolved in
150 g of solvent, water.
STEP 1: Solve for the molality of the solution, the unit of which is
mole solute/kilogram solvent. Using the dimensional analysis, the first
factor converts mass to mole, then divide with the mass of solvent, and
the last factor converts the mass in grams to kilogram.
𝐌𝐨𝐥𝐚𝐥𝐢𝐭𝐲 (𝑚) =
𝚫𝐓𝐛 = 𝐊𝐛 𝐱 𝐦
0.513 °C
x 0.068 m = 𝟎. 𝟎𝟑𝟓 °𝑪
1m
mole solute
kg solvent
1 mole
1
1 000 g
𝐌𝐨𝐥𝐚𝐥𝐢𝐭𝐲 (𝑚) = 3.5 g sugar x
x
x
342 g 150 g water
1 kg
𝐌𝐨𝐥𝐚𝐥𝐢𝐭𝐲 (𝑚) =
STEP 2: Solve for boiling point elevation
3500 mole
= 𝟎. 𝟎𝟔𝟖 𝐦𝐨𝐥𝐞/𝐤𝐠
51300 kg
STEP 3: Solve for boiling point of the solution
Boiling point of solution = boiling point of solvent +
ΔTb
62.8 0C = 61.2 0C + ΔTb
ΔTb = 62.8 − 61.2 = 𝟏. 𝟔 °𝑪
32
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
FREEZING POINT DEPRESSION
The freezing point of a substance is the temperature at which the solid and liquid phases coexist and their
vapor pressures are the same. If a nonvolatile solute is added to a solvent, the freezing point of the solvent is lowered
and the reduction in the freezing point depends on the number of moles of solute present. Again, the effect of
electrolytes as solutes is greater than nonelectrolytes because electrolytes ionize in solution and as such contain a
greater number of particles. The greater the number of solute particles, the greater the effect on the reduction of the
freezing point.
If one mole of nonelectrolyte solute is dissolved in one kilogram of water, the freezing point of water is
reduced by 1.86 °C. If two moles of nonelectrolyte solute dissolved in one kg of water, then the freezing point is
reduced by 3.72 °C. In other words, the freezing point depression constant for water (Kf) is 1.86 °C/1 molal solution
and Kf varies depending on the solvent. The identity of the solute does not have any effect on the freezing point just
like in the vapour pressure and boiling point. The freezing point depression then is equal to
ΔTf = Kf x m ΔTf = freezing point of pure solvent - freezing point of a solution
Freezing point solution = freezing point solvent - ΔTf
Solvent
Molal Freezing Point Depression Constant
Kf (0C/m)
Freezing Point 0C
Acetic acid (CH3COOH)
Benzene (C6H6)
Naphthalene (C6H8)
Chloroform (CHCl3)
Water (H2O)
Example
3.90
5.12
7.00
4.68
1.86
16.6
5.51
80.2
-63.5
1.86
What is the freezing point depression when 155 g of Iodine (I2) crystals is added to 1200 g of
benzene? Kf benzene = 5.12 0C/m FP benzene = 5.51 0C
STEP 1: Solve for the molality of benzene
1 mole I2
1
1000 g benzene
x
x
254 g
1200 g benzene
1 kg benzene
𝟎. 𝟓𝟎𝟗 𝐦𝐨𝐥𝐞
=
𝐤𝐠
STEP 2: Solve for freezing point
depression
155 g I2 x
𝚫𝐓𝐟 = 𝐊𝐟 𝐱 𝐦
=
5.12 °C
x 0.509 m = 𝟎𝟐. 𝟔𝟏 °𝐂
1m
SCIENCE
OVERLOAD
An application of freezing point depression is the addition of rock salt to ice
on wintry roads to melt the ice and snow. NaCl when dissolved in water
lowers the freezing point of water several degrees.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
33
FLASH CHECK
4
PROBLEM
PROBLEMSOLVING
SOLVING
1. What is the molality of a solution dissolved in chloroform that boils at 62.8 0C? Boiling
point of chloroform is 61.2
62.2 0C? Kb chloroform 3.63 0c/m
2. A solution prepared from 0.3
boiling point of 0.392 0C higher
solute?
g of an unknown nonvolatile solute and 30 g CCl 4 has a
than that pure CCl4. What is the molecular weight of the
QUICK
CONNECT
The greatest application of boiling point
elevation is in the preparation of candies. Sugar
and flavours are added to water and boil for a
long time to make the solution concentrated. As
the solution becomes more concentrated, the
vapor pressure is reduced and the boiling point is
increased. A candy thermometer determines if the
candy is ready for the next procedure. Syrup is
prepared in the same manner. A dilute sugar
solution is boiled for a long time to make it very
concentrated. The temperature is monitored to
determine when the desired concentration of the
syrup has been attained.
34
REFERENCES
• Breaking through chemistry p. 336 - 370
• General Chemistry 2 pp. 50 - 52
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
THERMODYNAMICS vs.
THERMOCHEMISTRY
Coffee in a bottle
or
Coffee in a thermos jug
INSTANT TASK
Decipher the Mystery Word! Using the Morse Code, decode
the unknown word below.
___ / . . . . / . / .___. / ___ ___ / ___ ___ ___ / ___ . ___ . /
. . . . / . / ___ ___ / . . / . . . / ___ / . ___ . / ___ . ___ ___
Mystery Word: _________________________________________________
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35
DIRECT TALK
First Law of Thermodynamics
THERMODYNAMICS
Is the study of processes which
involve heat transfer and the
performance of work.
The term thermodynamics is derived from the Greek word
"themes" which means heat and "dynamo" which means power.
Thermodynamics deals with the study of energy and its transformation. This
field of study will help in understanding the relationship between heat and
work in all living and nonliving things. A living cell, for instance, evolves heat,
does not work, and utilizes energy obtained from burning of food. Burning of
gasoline inside an internal combustion engine provides the push that propel
the vehicle, aside from giving out heat. A moving machine that does work
also generates heat. Thermodynamics will provide guidelines that will enable
us to understand the energies and directions of reactions.
TAKE
NOTE
Enthalpy of Chemical Reactions
The term enthalpy, from the Greek word, enthalpein, meaning "to
warm" refers to the energy transferred under constant pressure. It is represented
by the symbol, H. It is often referred to, as heat content. Like E (internal energy),
enthalpy, H, is also a state function, and therefore, not path dependent. Enthalpy
cannot be measured, but, it is possible to measure the change in enthalpy or heat
content, ΔH.
Internal energy (E) is the sum of the kinetic and potential energy found in
the system. It is the total energy found on the system being studied. However, this
is not quantifiable. But internal energy also changes as the system changes.
THERMOCHEMISTRY
Is the study of this heat
exchange and work on
chemical reactions. The law of
conservation of energy states
that the total energy of universe
is constant.
Energy univ = constant
Hess's Law
For any chemical reaction at
standard conditions, the
standard enthalpy change is
the sum of the standard
molar enthalpies of formation
of the products (each
multiplied by its coefficient in
the balanced chemical
equation) minus the
corresponding sum for the
reactants.
36
According to Germain Hess, a Russian chemist, the enthalpy change is the
same whether a reaction takes place in one step or a series of steps. For a chemical
reaction that takes place using different pathways, overall enthalpy change is the
same regardless of the route, so long as initial and final conditions are the same.
Hess's Law states that the enthalpy change of an overall reaction is the sum of the
enthalpy change of its individual steps. Since enthalpy is a state function where the
final and initial states are the only important states, the individual equations and their
known enthalpy can be manipulated to determine the enthalpy of the reaction.
A thermochemical equation can be expressed as the sum of two or more
equations, overall equation = equation 1 + equation 2 + ………..and, ΔH0 for the
overall equation is the sum of the ΔH0 for the individual equations:
ΔH0 = ΔH1 + ΔH2 + …..
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
Example:
1.) S (s) + O2 (g) → SO2 (g)
ΔH0 = -296.8 kJ
2.) 2SO (s) + O2 (g) → 2SO3 (g)
ΔH0 = -798.4 kJ
3.) S (s) + 3/2O2 (g) →SO3 (g)
ΔH0 = ?
STEP 1
Identify the net equation whose ΔH0 is unknown. Make sure that the reaction is balanced.
S (s) + 3/2O2 (g) → SO3 (g)
ΔH0 = ?
STEP 2
Manipulate equations where ΔH0 is known so that the correct moles of reactants and products are
on correct sides. Remember that reversing the direction of the reaction will give a ΔH0 of the same
magnitude but with different sign. Multiplying or dividing the reaction by a factor should be done to both the
ΔH0 value and the reaction.
S (s) + O2 (g) → SO2 (g)
ΔH0 = -296.8 kJ
2SO (s) + O2 (g) → 2SO3 (g)
ΔH0 = -798.4 kJ
STEP 3
Add these individual reactions to get the net reaction. The value of the unknown ΔH0 is the sum of
the individual manipulated ΔH0.
S (s) + O2 (g) → SO2 (g)
ΔH0 = -296.8 kJ
SO2(s) + 1/2O2 (g) → SO3 (g)
ΔH0 = -399.2 kJ
S(s) + 3/2O2 (g) → SO3 (g)
ΔH0 = -696.0 kJ
STRATEGY
In applying Hess's Law, equations can be arranged so that the desired
reactants and products will appear in the overall reaction. If the equation
is reversed, the sign of ΔH0 must be reversed. If the equations are
multiplied by a factor to obtain the desired coefficients, the ΔH0 values
should also be multiplied by the same number.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
37
FLASH CHECK
4
PROBLEM SOLVING
1.) Calculate the standard enthalpy of formation, ΔH0 for methane gas, CH4, produced from graphite
and hydrogen gas according to the following reaction:
C (graphite) + 2H2 (g) → CH4 (g)
Analysis: Since this reaction that forms methane gas does not take place as written, ΔH0 of methane
is determined indirectly by using the following set of reaction whose ΔH0 values have been accurately
determined and applying Hess's Law.
A. Write equation (1) as is.
1.) C (graphite) + O2 (g) → CO2 (g)
ΔH0 = -393.5 kJ
2.) H2 (g) + 1/2O2 (g) → H2O (l)
ΔH0 = -285.8 kJ
3.) CH4 (g) + 2O2 (g) → CO2 (g) + 2HO2 (l)
ΔH0 = -890.4 kJ
B. Multiply reaction (2) by two
including the value of ΔH0.
C. Rewrite reaction (3) in the reverse
direction and change the sign of ΔH0
from - to +.
D. Add the equations algebraically.
Substances that appear on opposite
sides of the equation may be
cancelled.
QUICK
CONNECT
Hess's Law can be applied to sever
every day factors, such as the engine in
your car which turns the heat
of combustion of the fuel, through several
steps, into the energy which is translated to
the movement of the car. This can be
applied industrially as the engineers
creating the cars can use it to determine if
new fuels would heat the engine more or
less and how they would affect the ability of
movement and speed of the car.
38
REFERENCES
• Breaking through chemistry pp. 410 - 420
• World of chemistry pp. 72 - 83
• Applications - Thermodynamics- Enthalpy/Hess's
Law (google.com)
• Coffee Cup Vector PNG & Download
Transparent Coffee Cup Vector PNG Images for
Free - NicePNG
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
Colligative Properties of Solutions
INSTANT TASK
Study the disorganized letters. Try to organize or rearrange the letters to form
the exact word based on the supported description.
A property of a solution that is dependent
on the ratio between the total number of
solute particles (in the solution) to the total
number of solvent particles.
RGASU
LGVEICOALTI TYPPOERR
A sweet crystalline substance obtained from various
plants, consisting essentially of sucrose, and used as
a sweetener in food and drink.
A colorless crystalline compound occurring naturally
in seawater and halite; common salt.
VRULASINE NLEVSTO
MUSDOI RDLEOCIH
A substance that dissolves most chemicals. Water is
referred as this because it dissolves more substances
than any other solvent.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
39
A colligative property is a property of a solution that is dependent on the ratio between the
total number of solute particles (in the solution) to the total number of solvent particles. Colligative
properties are not dependent on the chemical nature of the solution’s components. We can observe
the colligative properties of solutions by going through the following examples. If we add a pinch of
salt to a glass full of water, its freezing temperature is lowered considerably than the normal
temperature. Similarly, if we add alcohol to water, the solution’s freezing point goes down below the
normal temperature that is observed for either pure water or alcohol.
Different Types of Colligative Properties of Solution
Recall that the vapor pressure of a liquid is
determined by how easily its molecules are able to
escape the surface of the liquid and enter the gaseous
phase. This vapor pressure is temperature dependent: the higher the temperature, the higher the
vapor pressure. When a liquid evaporates easily, it will have a relatively large number of its molecules
in the gas phase and thus will have a high vapor pressure. Liquids that do not evaporate easily have a
lower vapor pressure.
The figure below shows the surface of a pure solvent compared to a solution.
Vapor Pressure Lowering
Red ones are the
nonvolatile solutes
REMEMBER! Vapor pressure of a
solvent is bigger than vapor
pressure of a solution.
In the picture on the left (pure solvent), the surface is entirely occupied by liquid molecules,
some of which will evaporate and form a vapor pressure. On the right (solution), a nonvolatile solute
has been dissolved into the solvent. Nonvolatile means that the solute itself has little tendency to
evaporate. Because some of the surface is now occupied by solute particles, there is less room for
solvent molecules. This results in less solvent being able to evaporate. The vapor pressure of a
solvent is lowered by the addition of a non-volatile solute to form a solution. By definition, a
non-volatile substance does not evaporate.
The boiling point of a solvent will increase when a
solute is dissolved in it. This is referred to as boiling
point elevation. The elevation of the boiling point is
directly dependent on the amount of solute present in the solution, but it is not based on the identity of
the solute, so it is considered a colligative property. We know that on the addition of a non-volatile
liquid to a pure solvent, the vapor pressure of a solution decrease. Therefore, to make vapor pressure
equal to atmospheric pressure, we have to increase the temperature of the solution.
The most common example of this phenomenon is that the boiling point of water is increased by
adding salt to the water. Basically, it is the temperature change (rising) of the boiling point of solvent
caused by adding a solute.
Boiling Point Elevation
Freezing Point Depression
When a substance is dissolved in water or some other solvent, the freezing point
is lowered. This observation can be explained based on the lowering of the vapor
pressure of a solution. When we add a solute to the solvent, some of the molecules
40
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
take up spaces at the surface of the liquid. As we know, to vaporize, solvent
molecules must be present at the surface of the solution. Adding about 68.5 grams of salt to
1 liter of water lowers its freezing point by 1.86 degrees Celsius (3.4 degrees Fahrenheit).
When salt is added to an icy road, it dissolves into water above the ice and keeps it from
freezing even though the temperature of the road is lower than 0 degrees Celsius -- the
freezing point of water.
Osmotic pressure can be thought of as the pressure
that would be required to stop water from diffusing through a
barrier by osmosis. In other words, it refers to how hard the
water would “push” to get through the barrier called semipermeable membrane, in order to diffuse to the other side. A
semipermeable membrane is a layer that only certain molecules
can pass through. Semipermeable membranes can be both
biological and artificial.
When we sit in the bathtub or submerge our fingers in
water for a while, they got wrinkly. And that is too because of
osmosis. The skin of our fingers absorb water and get expanded
or bloated; leading to the pruned or wrinkled fingers.
You must have heard about the killing of slugs or snails
by putting salt on it. The liquid inside them comes out and try
to dilute the salt concentration and maintain the mucus layer,
and hence, they end up shedding water. Too much salt and
slugs or snails will dry up and die!
Osmotic pressure is determined by solute concentration – water will “try harder” to diffuse into
an area with a high concentration of a solute, such as a salt, than into an area with a low
concentration.
Osmotic Pressure
Electrolytes are chemical compounds that can break down into ions when dissolved in
water. These ions can conduct electricity through this aqueous solution. There are two types of
electrolytes: strong electrolytes and weak electrolytes. Strong electrolytes readily produce ions when
they are soluble. For example, strontium hydroxide, Sr(OH)2 is partially dissolved in water. But it is a
strong electrolyte since the amount that is dissolved is completely ionized. Moreover, salts such as
NaCl, MgCl2 are also strong electrolytes since they are ionic compounds with a high degree of ionic
characteristics. Nonelectrolytes are chemical compounds whose aqueous solutions cannot conduct
electricity through the solution. These compounds do not exist in ionic form. Most nonelectrolytes are
covalent compounds. When dissolved in water, these compounds do not form ions at all. Sugars,
fat, and alcohols are examples of nonelectrolytes.
Different Types of Colligative Properties of Solution
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
41
1. Identify whether the following statements are TRUE or FALSE.
_________________ 1. Salt water solution will boil faster than just water alone.
_________________ 2. The higher the temperature, the higher the vapor pressure.
_________________ 3. A glass of water will evaporate faster than a glass of soda.
_________________ 4. A dissolved sugar in H2O can conduct electricity but will
evaporate slowly.
_________________ 5. The effect of electrolytes on colligative properties is very low
compared to nonelectrolytes.
2. Observe from your surroundings. Pick one from the different types of colligative
properties and cite one example that best exhibits it. Explain.
Example: When we soak resins in water they swell up. This happens due to
osmotic pressure. Water travels from high concentration to low concentration and
keeps moving by osmosis until the equilibrium is reached, that is when the
concentration of both solutions is the same.
Answer to
START-UP
We tend to drink lots of water after consuming salty foods because salt is a solute and
after consuming lots of salt, our cells become concentrated with salt, which triggers the
process of thirst. So, our cells absorb water and we feel thirsty, and hence, we start
drinking water.
References:
QUICK
CONNECT
Salt water helps you
relieved from sore throat
get
In case you have a sore throat,
cells and tissues surrounding the
throat are swollen because of the
excess of water. The salt water
which we use for gargles has a
lower concentration of water than
the cells of the throat. So, water
molecules move from the swollen
cells of the throat to the salt
water; reducing pain and swelling.
42
1.
2.
3.
4.
http://www.chem4kids.com/
https://study.com/academy/le
sson
https://www.ck12.org/
https://opentextbc.ca/
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
Rates of Reaction
INSTANT TASK
LET’S DO THE NAKED EGG EXPERIMENT! Prepare these materials for this fun and
interesting activity. You will need:
✓ Raw egg
✓ Vinegar
✓ A glass container with
a tight lid
Questions: (You must finish the
experiment first to answer the following
questions.)
1. Looking
at
the
physical
appearance of the egg, explain
how does it look like after
soaking for 24 hours.
2. What have you noticed in the
vinegar at the container?
3. Touching the egg after 24
hours of soaking, explain how
does it feel.
4. Remove the raw egg from the
vinegar and allow it to sit out
on the table for one (1) day.
What have you observed to the
egg?
Instructions:
1. Place an egg inside a large glass container,
such as a beaker or jar. If you want to
make more than one naked egg, make sure
the eggs do not touch inside the container.
2. Pour enough vinegar into the jar to cover
the egg completely. The egg might float to
the top, but the vinegar should still cover
most of the egg.
3. Set your jar aside and wait 12 to 24 hours
for the eggshell to dissolve.
4. Pour out the vinegar carefully and catch the
naked egg in your hand. You may also use
a wooden spoon to remove the egg, but
this method might cause it to break. If a
small amount of white eggshell still remains
on the egg, you can lightly wipe it off with
your fingers. If the shell has not dissolved
enough, place the egg in a fresh jar of
vinegar for another 12 to 24 hours.
Write your answers in a separate sheet of paper!
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43
The rate of reaction or reaction rate is the
speed at which reactants are converted into
products. When we talk about chemical reactions, it is
a given fact that rate at which they occur varies by a
great deal. Some chemical reactions are nearly
instantaneous, while others usually take some time to
reach the final equilibrium.
Example:
Wood combustion has a high reaction rate since the process is fast and rusting of iron has a
low reaction rate as the process is slow.
Five Factors That Can Affect The Rates of a Chemical Reaction
For a chemical reaction to occur, there must be a collision between the reactants at the correct
place on the molecule, the reactive site. If the collision doesn’t transfer enough energy, no reaction
will occur.
The various factors that can affect the rate of a chemical reaction are listed below:
Nature of the Reactants. The rate of reaction highly depends on the type and nature of the
reaction. As mentioned earlier, few reactions are naturally faster than others while some reactions
are very slow. The physical state of reactants, number of reactants, complexity of reaction and other
factors highly influence the reaction rate as well. The rate of reaction is generally slower in liquids
when compared to gases and slower in solids when compared to liquids. Size of the reactant also
matters a lot. The smaller the size of reactant, the faster the reaction.
The Temperature. According to collision theory, a chemical reaction that takes place at a higher
temperature generates more energy than a reaction at a lower temperature. This is because colliding
particles will have the required activation energy at high temperature and more successful collisions
will take place.
The
Concentration
of
Reactants.
Increasing the
concentration of the reactants (or pressure, if gases are involved)
normally increases the reaction rate due to the increased number of
collisions.
Less Concentrated
More Concentrated
Physical State of Reactants. Gases and liquids tend to react faster than solids because of the
increase in surface area of the gases and liquids versus the solid. If the size of a particle is small, the
surface area will be more and this increases the speed of heterogeneous chemical reactions.
Catalysts. A catalyst can be defined as a substance that increases or decreases the rate of the
reaction without actually participating in the reaction. The definition itself describes its effect on
chemical reactions. With a helping hand from a catalyst, molecules that might take years to interact
can now do so in seconds. All reactants need to overcome certain energy, better known as activation
energy in order to form products.
44
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
and how it affects the
chemical reaction
How do catalysts work? Particles stick
the surface of the catalyst (called
adsorption) and then move around, so they
are more likely to collide and react. A good
example is the way the platinum catalyst in a
car’s catalytic converter works to change toxic
carbon monoxide into less-toxic carbon dioxide
(see pictures in left). Another process of
catalyst affecting chemical reactions is called
reaction intermediate, wherein a catalyst
first combines with a chemical to make a new
compound. This new compound is unstable, so
it breaks down, releasing another new
compound and leaving the catalyst in its original
form. Many enzymes (special biological
catalysts) work in this way. One example of a
catalyst
that
involves
an
intermediate
compound can be found high in the Earth’s
atmosphere. Up there, the chemical ozone (with
molecules containing three oxygen atoms) helps
protect the Earth from harmful UV radiation.
But also up there is chlorine, which gets into
the
atmosphere
from
chemicals
(chlorofluorocarbons, CFCs) used in some
refrigerators, air conditioners and aerosol cans.
Chlorine is a catalyst, which steals an oxygen atom from ozone (O 3) leaving stable oxygen (O2). At the
same time, it forms an unstable intermediate chlorine-oxygen compound, which breaks down to release its
oxygen. This leaves the chlorine free to repeat the process. One chlorine atom can destroy about a million
ozone molecules every second. This can have a drastic effect on the atmosphere’s ability to protect us from UV
radiation.
onto
Types of Catalysts
Homogeneous Catalyst
Heterogeneous Catalyst
Biological Catalyst
Homogeneous catalysis of chemical
reactions is a process where the
reactants involved in the reaction and
the catalyst are in the same phase.
For example, if the reactants are
gases, then the catalyst is also a gas.
Heterogeneous catalysts are in a
different phase than the reactants. For
example, the reactants may be solid,
but the catalyst is a liquid.
Natural proteins (enzymes) or nucleic
acids (RNA or ribozymes and DNAs)
used to catalyze specific chemical
reactions outside the living cells are
called biocatalysts. Example: Yeast,
Bacteria, fungi, etc.
Activation Energy
Activation energy and catalyst are closely related because the function of the catalyst is to lower down
the activation energy so that more particle has enough energy to react. Activation energy is defined as the
minimum amount of extra energy required by a reacting molecule to get converted into product. It can also be
described as the minimum amount of energy needed to activate or energize molecules or atoms so that they
can undergo a chemical reaction or transformation.
Examples of Chemical reactions that require Activation energy:
✓
✓
The combustion reaction requires activation energy. Carbon and oxygen combine to form carbon
dioxide and transformed the energy.
Lighting a match which creates friction and turns to heat. The heat thus liberated then produce enough
activation energy that allows the chemical on the match to react and ignite the flame.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
45
Answer the following questions below. Write your answer in a separate sheet of paper.
1. Enumerate the five factors that affects the rate of chemical reaction.
2.
1. a.
b.
c.
d.
e.
2. Why does a chemical reaction that takes place at a higher temperature
generates more energy?
3. Explain how do catalysts work in a chemical reaction. Give examples.
4. What is the relation of activation energy and catalyst?
Answer to
START-UP
The rusting process of an iron is pretty much fast, not to mention if it’s in rough
climate, but we don’t want the process to occur, or at least we want to delay the
process, so we paint it, or cover it with a substance that slows down the process.
References:
QUICK
CONNECT
1.
2.
In wildlife, a wood
could
decompose in over 300 years if it
exposed to open air, but we want
the process faster to get heat out
of it, so we light the wood by
adding extra energy to fasten the
process.
46
3.
4.
http://www.chem4kids.com
/
https://study.com/academy
/lesson
https://www.ck12.org/
https://opentextbc.ca/
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
GENERAL
CHEMISTRY 2
Molecular Collisions
and the Orders of Reaction
INSTANT TASK
SHARING EXPERIENCES. Have you experienced colliding into something or someone
unexpectedly? Have you seen two things collided with an ear-splitting crash? A thing dropped
from a high place and crushed as it landed? Tell us your experience through writing an essay!
Relate your experience with the idea of molecular collisions.
____________________________________________________
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SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
47
What is Collision Theory?
When cars moving at a high speed collide with one another,
the result can be a particularly dramatic change. A high energy
collision can convert a functional car into a pile of scrap metal and
spare parts. On the other hand, a slower, low energy collision might
just cause a scratch or a minor dent.
Not all collisions are purely destructive. You are probably
familiar with the phrase, “You can’t make an omelet without breaking
some eggs.” Similarly, you can’t cause a chemical reaction without
breaking some bonds. Most chemical reactions occur only when reactants collide with one another.
However, not every collision leads to a chemical change. In order for a reaction to occur, the reactants
must collide in a certain relative orientation with enough energy to break one or more chemical bonds.
Based on this simple model, we can predict which factors will speed up or slow down a chemical
reaction.
Do you ever wonder how reactions actually happen? What are the conditions necessary for a
reaction to happen? Is it certain that a reaction will take place even after the conditions are fulfilled?
The answer to all these questions is Collision Theory.
The collision theory states that a chemical reaction can only occur between particles
when they collide (hit each other). The collision between reactant particles is necessary but not
sufficient for a reaction to take place. The collisions also have to be effective. It is important to
understand the exact nature of an effective collision since this determines whether particles react with
each other and form new products.
The more molecules are present, the more collisions will happen.
Molecules must collide before they can react.
To effectively initiate a reaction, collisions must be sufficiently energetic (kinetic
energy) to bring about this bond disruption.
The molecules must collide with energies greater than or equal to the activation energy of the reaction. If
this does not happen the reaction will not take place. The molecules need the energy to break their existing bonds
and form new bonds. This is the kinetic energy that the molecules possess. If this energy is not equal to or
greater than the activation energy, the reaction will not proceed.
As the temperature rises, molecules move faster and collide more vigorously,
greatly increasing the likelihood of bond cleavages and rearrangements.
Most reactions involving neutral molecules cannot take place at all until they have
acquired the activation energy needed to stretch, bend, or otherwise distort one or
more bonds.
48
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
Orders of Reaction Explained
The order of the reaction is a relationship between the rate of a chemical reaction and the
concentration of the species.
But remember! Orders of reaction are always found by doing experiments. You can't deduce
anything about the order of a reaction just by looking at the equation for the reaction. This topic
will introduce you the basic concept of the orders of the reaction. First, let us discuss the
relationship of the reaction orders to the Rate Law.
For any general reaction occurring at a fixed temperature:
The term k is the rate constant, which is specific for a given reaction at a given
temperature.
The exponents m and n are reaction orders and are determined by experiment. The value
of m and n are not necessarily related in any way to the coefficients a and b.
A reaction has an individual order ““with respect to” or “in” each reactant.
For the simple reaction A → products:
✓ If the rate doubles when [A] doubles, the rate depends on [A]1 and the reaction is
first order with respect to A.
✓ If the rate quadruples when [A] doubles, the rate depends on [A]2 and the reaction
is second order with respect to A.
✓ If the rate does not change when [A] doubles, the rate does not depend on [A], and
the reaction order is zero order with respect to [A].
Individual and Overall Reaction Orders
Example: Determining Reaction Orders from Rate Laws
For the reaction:
2NO + 2H2 → N2 + 2H2O
The rate law is:
k [NO]2[H2]
Answer: The reaction order is second order with respect to NO, first order with respect to H2
and third order overall (addition of all exponents).
Note that the reaction order is first order with respect to H2 even though the coefficient for H2 in
the balanced equation is 2. This is because as stated from above, that the value of m and n are not
necessarily related in any way to the coefficients a and b.
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
49
Answer the following questions. Write your answer in a separate sheet of paper.
1. In your own words, explain the collision theory.
2. Differentiate the orders of reaction.
3. Determine the reaction orders from the given rates:
a.)
b.)
Answer to
START-UP
Molecules with greater kinetic energy diffuse faster; in other words, the rate of
diffusion increases as kinetic energy increases. For example, the food coloring
will spread out faster in the warmer water because of greater kinetic energy.
QUICK
References:
CONNECT
The game of pool provides an
example of a collision in which one
object, the cue ball, is moving,
while the other—known as the
object ball—is stationary. Due to
the hardness of pool balls, and
their tendency not to stick to one
another, this is also an example of
an
almost
perfectly
elastic
collision—one in which kinetic
energy is conserved.
50
1.
2.
3.
4.
http://www.chem4kids.com/
https://study.com/academy/le
sson
https://www.ck12.org/
https://opentextbc.ca/
Read
more:
http://www.scienceclarified.com/e
veryday/Real-Life-Chemistry-Vol-3Physics-Vol-1/Momentum-Real-lifeapplications.html#ixzz6ng39JSBT
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
The Temperature Curve and
The Phase Changes of Water and
CO2
INSTANT TASK
1.
2.
3.
4.
5.
6.
7.
8.
Gas
C
Liquid
B
Solid
A
Gas - Liquid
Liquid – Solid
FLASH CHECK
a.
b.
c.
d.
e.
f.
Solid
Liquid
Gas
Liquid
Gas
Gas
START - UP
- THEIR SIMILARITIES ARE NOT BASED
ON THE COMPOSITION OR STRUCTURE
OF
THE
CONTAINER.
THEIR
SIMILARITIES ARE BASED ON THEIR
SURROUNDINGS IN THE FORM OF
HEAT AND ON THEIR ABILITY TO DO
WORK ON THE SURROUNDINGS.
INSTANT TASK
1.
2.
3.
4.
5.
6.
7.
8.
9.
CRYSTALLINE
AMORPHOUS
MOLECULAR
IONIC
METALLIC
COVALENT
POLAR
NON-POLAR
HYDROGEN BONDED
FLASH CHECK
- ANSWERS MAY VARY
SCIENCE POCKET LESSON 5
SCIENCE POCKET LESSON 4
INSTANT TASK
*SOLID
1. ICE
2. BOOK
3. WOOD
4. BLOCK
5.
*LIQUID
1. MILK
2. WATER
3. JUICE
4. COFFEE
5. PAINT
*GAS
1. BALLOON
2. CLOUD
3. TORNADO
4. AIR
5. BOILING
1. INTERMOLECULAR
2. SURFACE TENSION
3. BOILING POINT
4. VISCOSITY
5. LIQUIDS
6. VAPORIZATION
7. MOLAR
8. FORCES
9. HEAT
10. VAPOR
- ANSWERS MAY VARY
- SURFACE TENSION
- ICE IS ACTUALLY ABOUT 9% LESS DENSE
START-UP
START - UP
THAN
WATER.
SINCE
THE
WATER
IS
HEAVIER, IT DISPLACES THE LIGHTER ICE,
CAUSING THE ICE TO FLOAT TO THE TOP.
INSTANT TASK
1. WATER
2. FREEZING POINT
3. BOILING POINT
4. SHAPE
5. SOLID
6. LIQUID
7. GAS
8. SOLID
9. LIQUID
10. GAS
START-UP
INSTANT TASK
FLASH CHECK
1.
2.
3.
FLASH CHECK
FLASH CHECK
ANSWERS MAY VARY
1. LONDON DISPERSION FORCES (Ar)
2. DIPOLE-DIPOLE, H-BOND (CH3CH2OH)
3. DIPOLE-DIPOLE, H-BOND (HF)
4. DIPOLE-DIPOLE (BaCl2)
- ANSWERS MAY VARY
SCIENCE POCKET LESSON 2
SCIENCE POCKET LESSON 1
SCIENCE POCKET LESSON 3
ANSWER KEY
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
- ANSWERS MAY VARY
INSTANT TASK
START-UP
Colligative Properties of Solutions
1.
2.
3.
4.
Colligative Property
Sugar
Sodium Chloride
Universal Solvent
1. TRUE
2. TRUE
3. TRUE
4. FALSE
5. FALSE
(Answers may vary.)
5 grams of flour, 100
grams of butter, ½ cup of
sugar, 5 cookies
2NaN3 → 2Na + 3N2
START-UP
INSTANT TASK
INSTANT TASK
- C (graphite) + 2H2 (g) → CH4 (g)
ΔH0 = -74.7 kJ
FLASH CHECK
1. 0.441 m
2. 128 g/mol
Concentrations of Solutions
INSTANT TASK
INSTANT TASK
1.
2.
- ANSWERS MAY VARY
1. BOILING POINT
2. FREEZING POINT
-THERMOCHEMISTRY
FLASH CHECK
FLASH CHECK
A.
B.
SCIENCE POCKET LESSON 10
Stoichiometric Calculations for
Reactions in Solutions
SCIENCE POCKET LESSON 9
1.
2.
3.
15% apples are bad.
25%
Php 562.50
FLASH CHECK
a.
FLASH CHECK
1.
SCIENCE POCKET LESSON 8
a. 200g C3H8 = 4.54 mol
C3H8
b. (ratio of H2O to C3H8=
4:1); for every 4.54 mol
C3H8 there are 18.18 mol
H2O
c. 18.18 mol H2O is equal
to 327.27 g H2O.
(2 x 12) + (5 x 1.008) + (1 x 14) + (2 x 16) = 75.04 g/mol →
molar mass
[0.000889 g C2H5NO2 x (1 mol C2H5NO2 / 75.04 g C2H5NO2) =
1.18 x 10-5 mol HCl
Convert 1.05mL to L = 0.00105 L
M = 1.18 x 10-5 mol HCl / 0.00105 L = 0.0112 M C2H5NO2
(0.6 g Pb / 277 g solution)(1000000) = 2166 ppm
(90mL / 3000mL)(100%) = 3%
25 g KBr x (1 mol KBr / 120 g KBr) x (1 / 0.75 L) = 0.278 M
(25 g / 46.07 g/mol) = 0.543 moles ethanol
(25 g / 18 g/mol) = 1.389 moles water
Total number of moles in the solution = 0.543 + 1.389 = 1.932
moles
Mole fraction of ethanol = (0.543 / 1.932) = 0.281
Mole fraction of water = (1.389 / 1.932) = 0.718
c.
d.
e.
f.
(36.5 g / 355 g)(100%) = 10.3%
b.
SCIENCE POCKET LESSON 6
SCIENCE POCKET LESSON 7
SAN PEDRO RELOCATION CENTER NATIONAL HIGH SCHOOL – SCIENCE DEPARTMENT © 2020
INSTANT TASK
INSTANT TASK
Rates of Reaction
Molecular Collisions and the Orders of Reactio
1.
(Answers may vary.)
(Answers may vary.)
FLASH CHECK
FLASH CHECK
1.
2.
3.
(Answers may vary.)
(Answers may vary.)
a. The exponent of [NO] is 2 and the
exponent of [O2] is 1, so the reaction order
is second order with respect to NO, first
order with respect to O2, and third order
overall.
b. The reaction is first order in H2O2, first
order in I-, and second order overall. The
reactant H+ does not appear in the rate
law, so the reaction is zero order with
respect to H+.
1.
Five factors:
a. Nature of the
Reactants
b. Temperature
c. Concentration of
Reactants
d. Physical State of
Reactants
Catalysts
e.
2 – 4. (Answers may vary based on
student’s interpretation.)
SCIENCE POCKET LESSON 11
SCIENCE POCKET LESSON 12
ANSWER KEY