CHEM 1411- CHAPTER 1
CHEMICAL FOUNDATIONS
Matter:
Anything that has mass and occupies space is called matter.
Physical Change
A physical change is the one that can be observed or measured without changing the chemical
composition.
Examples: Density, Melting Point, Boiling Point, Color.
A Chemical change is the one that always change the chemical composition of matter
Examples: Burning of hydrogen in air, Electrolysis of water into hydrogen and oxygen.
Intensive and Extensive Properties
Properties of matter that are independent on the quantity of matter contained in it are Intensive
properties. Example: Color, Density, Odor, Surface Tension, Refractive index Temperature, Pressure.
Properties of matter that are dependent on the quantity of matter are Extensive properties.
Ex. Mass, Volume, Energy, heat Capacity.
Classification of Matter based on composition.
Matter is classified as pure substances and Mixtures.
Pure Substances: Further classified into Elements and Compounds.
An element is a pure substance consisting of same kind of atoms (Hydrogen, Copper, and Silver). It
cannot be decomposed into simpler substances or created by combining simpler substances.
A compound is a pure substance formed by the combination of two or more elements (Table salt,
Calcium Carbonate). It can be decomposed into smaller substances.
Mixtures: A mixture consists of two or more different substances. They are further classified into
Homogeneous and Heterogeneous mixtures.
A homogeneous mixture is the one that has a uniform composition throughout. (Ex: NaCl (aq),
Sugar solution in water, alloys)
A heterogeneous mixture is the one that does not have a uniform composition (ex. Sand and water;
Pepper and Salt)
Classification of matter based on Physical state.
Matter is classified as Solids, Liquids and Gases.
Separation of Mixture
The common methods of separation are,
Filtration: Used to separate an insoluble substance from a liquid using a filter paper
Distillation: To separate a solid and liquid from a solution by heating
Fractional Distillation: To separate two or more miscible liquids with difference in boiling point
Magnetic Separation: to separate a magnetic substance from a non-magnetic one using a magnet
Sublimation: Sublimation is the process of conversion of a solid directly into the gaseous state.
Names of some common elements and their symbols. Symbols are derived from their Greek
,Arabic or Latin names. The first letter is always Capital and the second one is a small letter.
Sodium, Na (Natrium) Iron, Fe (Ferrum) Potassium, K (Kalium) Hydrogen, H
Carbon, C Oxygen, O Aluminum, Al
Scientific Method
It is a systematic investigation of nature and requires proposing an explanation for the results of an
experiment in the form of a principle.
Hypothesis
A tentative proposal of a scientific principle is called a Hypothesis.
Theory
A hypothesis, which has sufficient evidence established through experiments, is called a Scientific
Theory. A theory explains the behavior of nature.
Law
A natural law does not explain the behavior, but gives a measurable relationship.
Consider the case when we drop ice into water,
Transfer of heat takes place from hotter objects to cooler one. This is a law because we can measure
experimentally the change in temperature.
Transfer of heat is due to the movement of molecules of ice and water. This is a theory.
Measurements and Metric system:
The measurement system in science and technology is called the metric system (Systeme
International d’Unites (S.I. system)
Ex: Length (m), Mass (kg), Temperature (Kelvin), Time (s), Amount of Substance (mol),
Electric Current (Ampere), Luminous Intensity (Candela).
Area (m2), Volume (m3), Density (kg/m3), Velocity (m/s)
Some conversions:
109
1 Giga
6
10
1 Mega
103
1 Kilo
2
10
1 Hecto
10
1 Deka
10-1 (0.1)
1 Deci
-2
10
1 centi
10-3
1 Milli
-6
10
1 Micro
10-9
1 Nano
-12
10
1 Pico
(1meter = 10 Decimeter)
(1meter = 100 Centimeter)
(1meter = 1000millimeter)
(1meter = 1000000micrometer)
(1meter = 109nanometer)
(1meter = 1012picometer)
1 in = 2.54 cm, 1 cu.ft = 28.32 L, 1 lb = 453.59 gm
39.37 in = 1m, 1.057 qt = 1L, 1 ounce = 28.35 g, 1 mile= 1.609 km, 1 gallon = 3.7853 L, 1 dram =
1.772 g.
Precision and Accuracy:
Precision is a measure of how closely individual measurements agree with one another.
Accuracy refers to how closely individual measurements agree with the correct or true
value.
Significant figures:
Significant figures are the meaningful digits in a measured or calculated quantity. The
number of significant figures is equal to the number of digits that are certain and the one that
is uncertain.
Rules for assigning significant figures
1. All non-zero digits are significant
2. Trailing zeros in a decimal number are significant.
3. Zeros within two non-zero digits are significant.
4. Zeros before the first non-zero digit are not significant.
5. A number ending in zero with no decimal point is ambiguous. For such number,
we should use the scientific notation to decide the number of significant figures.
Rounding off.
Rule 1. If the digit following the last digit to be retained is less than five, the last
digit is left unchanged.
Rule 2. If the digit following the last digit to be retained is 5 or more than five, the
last digit retained is increased by one.
Scientific Notation or Exponential Notation:
Numbers wrote using a coefficient and an exponential factor.
Rules:
1. For a number greater than 1, the decimal is moved to the left to create a coefficient
between 1 and 10. Assign a suitable exponential factor using a suitable positive power of
10, which is equal to the number of places the decimal point was moved.
2. For a number less than 1, the decimal is moved to the right to create a coefficient
between 1 and 10. Assign a suitable exponential factor using a suitable negative power
of 10, which is equal to the number of places the decimal point was moved.
Addition, Subtraction, multiplication and division in scientific notation
For addition and subtraction modify the numbers such that the exponents are equal. For
multiplication, multiply the coefficients and add the exponents.
For division, divide the coefficients and subtract the exponents of 10 in the denominator
from the exponents of 10 in the numerator.
Calculation based on significant figures.
Rules:
1.In addition or subtraction the final result should be reported to the least number of
decimal places as the number with minimum # of decimal places.
Q. Perform the following calculations to the correct number of significant figures.
a) 35.52+10.3 b) 3.56-0.021
2. In multiplication or division the result should be reported to the minimum number of
significant figures as the number with least # of significant figures.
Q. Perform the following calculations to the correct number of significant figures.
a) 6.26 x 5.8
b) 5.27/12
3. If some exact number is involved the calculation, the result is limited to the number of
digits in the other number
11 apples x 0.250g
Fundamental Properties of Matter
1. Mass
It is a measure of the quantity of matter. SI unit of mass is ‘kg’
What is the difference between Mass and Weight? Mass has weight because of
gravitational force. An object’s mass at Mount Everest, at sea level and in space is same.
But the weight of the same object is different at these 3 locations .It is maximum at sea
level, less at mount Everest and least (weightless) in space. Explain the reason.
2. Volume
It is the amount of space that a sample of matter occupies. SI unit Liter
Density
Density of a substance is defined as the mass of the substance per unit volume.
Density = mass (g)
Volume (ml)
Order of density of a substance
Solid > Liquid > gas
A rise in temperature decreases the density of a substance because though the mass
remains same, volume increases with rise in temperature.
Density of urine is measured to evaluate the kidney function. Density of urine increases as
the amount of dissolved solids increase.
Specific Gravity =
Density of test liquid
Density of reference liquid
Hydrometers are used to measure the specific gravity.
Temperature
It is the measure of the “hotness” or “coldness” of the body. It is measured using a device
called the Thermometer. The SI unit is Kelvin. Other common units are Celsius and
Fahrenheit.
Kelvin= 0C + 273.15
0C = (0F – 320F) x (5/9)
0F
= 0C x (9/5) + 320F
Dimensional Analysis
The procedure used to convert between units in solving problems is called dimensional
analysis.
For Example,
1 Dollar = 100 pennies
The conversion factor used is
1 Dollar
100 Pennies
or
100 Pennies
1 Dollar