Western Sierra 2010-2011
FINALS STUDY GUIDE
Solutions
Vocabulary and Concepts
Solution –
Solute –
Solvent –
Suspension –
Colloid (Foam, emulsion, aerosol)Disassociation –
Constant of Disassociation Homogeneous Mixture –
Heterogeneous Mixture –
Electrolyte –
Concentration –
Hydrates –
Solubility –
Saturated –
Unsaturated –
Supersaturated –
Concentration Colligative Properties –
Boiling Point Elevation –
Freezing Point Depression –
Vapor Pressure Depression –
CHEMISTRY
NAME______________
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Western Sierra 2010-2011
FINALS STUDY GUIDE
CHEMISTRY
NAME______________
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Name (Label)
Equation
Molarity (M)
moles solute / liters of solution
Use when: Normal way to express the concentration of a solution
Notes: Liters of solution, not liters of solute. To make these, you have to get it dissolved first in some solvent, and then
add more solvent until you have the volume you intended. This makes preparing them somewhat tricky. (p. 481 top)
The solute takes up some volume even when dissolved.
Example: 1 mol NaCl and about 960 mL water --> 1M NaCl Solution (comes out to about a Liter with this combination)
Molality (m)
moles of solute / kilograms of solvent
Use when: You want to calculate concentration ahead of time, instead of having to fuss around with the solution’s total
volume.
Notes:
Example: .5 mol in 1 kg of water --> .5m solution
Percent by volume (% v/v)
volume of solute / volume of solution
Use when: Drink industry. I don’t think it’s ever a good idea. When things form solutions, the final volume is always less
than the sum of the volume of the components, and this makes things confusing.
Notes: Seems easy, but oh the horror!!! Always label your % as a volume or mass-based one to avoid confusion
Example: 20 mL Ethyl Alcohol + 80 ml Water --> 95 mL of 20% (v/v) Ethyl alcohol
Percent by mass (% m/m)
mass of solute / mass of solution
Use when: Food industry, or you don’t have the time or need to do mole calculations but still want the information
available in case you change your mind later.
Notes: Always label your % as a volume or mass-based one to avoid confusion. Easiest one! Weigh them and make a
ratio.
Example: 10 kg scandium and 90 kg aluminum --> 10 % (m/m) scandium-aluminum alloy
Mole Fraction (dimensionless)
moles solute / (moles solute + moles solvent)
Use when: O-chem when water is not the solvent. Vapor pressure calculations.
Notes: The sum of all mole fractions for each part of the mixture must equal 1.
Example:
1.25 mol solution A, 4 mol solution B are mixed.
XA = nA / (nA + nB), XB = nB / (nB + nA), XA + XB = 1
Western Sierra 2010-2011
FINALS STUDY GUIDE
CHEMISTRY
NAME______________
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Practice Problems
Givens
Solute 1– 117.0 g Na2S
Solute 2 – 205.8 g NaBr
Solvent – 950.0 mL H2O
Density of H2O = 1.00 g/mL
Density of Na2S = 1.86 g/cm3
Density of NaBr = 3.21 g/cm3
Mass (g)
Volume (mL)
Moles
Na2S
117.0
NaBr
205.8
H2O
950.0
1) Convert your givens so that for each of the three compounds, you know a
mass, volume, and number of moles. Record your answers in the table
above, and show your work using dimensional analysis below to receive
credit. (3 pts)
Conversion 1.00 mL = 1.00 cm3
1000 mL = 1 L
Solubility of Na2S in water
18.6 g/100 mL (20 °C)
39 g/100 mL (50 °C)
Solubility of NaBr in water
90.5 g/100 mL (20 °C)
121.0 g/100 mL (100 °C)
Other data for water:
Vapor Pressure @ STP = 2300 Pa
Kf = 1.86 *C/m
Kb = .512 *C/m
Assume that when all three
compounds are combined, the
volume they occupy is one Liter.
Molarity
2) Complete the three types of concentration calculations for the solute, NaBr,
listed on the table below. (3 pts) Include the mass of the Na2S, but it can
otherwise be safely ignored.
% by volume
% by mass
Answer
3) Find the freezing point depression, boiling point elevation, and vapor pressure depression for the water when
both salts are present. (6 pts)
4) Create a solubility curve (scatterplot) for each salt and estimate how many grams of each could dissolve in 100
mL of water at 30*C. (2 pts) Use them to help answer the following questions.
5) What is the maximum amount of NaBr a 500mL solution of water at 50*C could dissolve?
6) Write a brief lab procedure for how would you create a 100mL solution of water that contains 40g of Na2S?
7) If both Na2S and NaBr are present in the solution, how would you qualitatively adjust the solubility chart?
8) What vocabulary would you use to describe solutions with 25g, 35g, 39.1g, or 45g of Na2S per 100mL of water at
20*C?
9) Briefly explain the difference between a colloid, suspension, and solution.
10) Explain how fractional distillation, filtration, and chromatography can be used to separate mixtures.
Western Sierra 2010-2011
FINALS STUDY GUIDE
CHEMISTRY
NAME______________
4
Acids and Bases
Vocabulary and Concepts
Acid, Base Definitions –
Arrhenius –
Bronstead-Lowry –
Lewis –
Conjugate –
Strong vs. Weak –
Neutralization –
Disassociation of water (kH2O)–
Buffer Solution –
pH Scale –
Finding pH and pOH –
Practice Problems
1) When 168g of the Bronstead-Lowry base NaHCO3 are added to 2L of pure water and the pH is measured to be
8.7, what is the disassociation constant for this chemical?
2) 50mL of .2M HCl are added to 150mL of a basic solution of unknown concentration, and a neutral solution is
produced. Assuming full disassociation by both solutions, what was the concentration of the basic solution.
3) 72.8g of HCl are added to 1000mL of water. The disassociation constant for HCl is 3*10^1. What is pH of this
solution?
4) Describe the purpose of a buffer solution, as well as how one can be made.
5) Give an example of each of the types of acids and bases.
6) Good black coffee has a pH of 5.3. Over-brewed bad black coffee has a pH of 4.9. The stomach has a pH range
between 1.0 and 3.0.
a) Will adding good coffee to the contents of the stomach increase the acidity and cause ulcers, as a well-known
saying suggests?
b) How much milk (pH of 8) must be titrated against bad coffee to bring the acidity down to ‘good coffee’ levels?
What portion of a typical Starbuck drink would you estimate is bad coffee, and how much is milk product? Does
this level of titration compensate?
Western Sierra 2010-2011
FINALS STUDY GUIDE
CHEMISTRY
NAME______________
Kinematic Theory of Matter, Reaction Rates, and Equilibrium
Vocabulary and Concepts
Kinematic Theory of Matter –
States of Matter –
Solid –
Liquid –
Gas –
Plasma –
Phase Change –
Melting, Freezing, Boiling, Evaporating, Condensing, Sublimating, Ionizing, De-ionizing etc...
Latent Heat of Fusion, Evaporation –
Specific Heat Capacity –
Reaction vs. Energy Diagrams Endo vs. Exothermic –
Catalyst (Enzyme when organic), Inhibitor –
Activation Energy –
Collision Theory Factors which affect reaction rate: Pressure (if gases), Temperature, Concentration, CatalystsLeChatelier’s Principle –
Enthalpy –
Entropy –
Gibbs Free Energy –
5
Western Sierra 2010-2011
FINALS STUDY GUIDE
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Gas Laws –
Ideal Gas Law –
Gay-Lussac’s Law –
Boyle’s Law –
Charles’ Law –
Dalton’s Law –
Graham’s Law –
Standard Temperature Pressure –
Practice Problems
1) Based on the following enthalpies of reaction, what is the enthalpy change for the reaction N2H4 + H2 --> 2NH3?
N2 + 2H2 --> N2H4
∆H = +50.6 kJ/mol
N2 + 3H2 --> 2NH3
∆H = -92.2 kJ/mol
2) You will always get a spontaneous reaction when you combine which of these two factors?
a. heat released, entropy increases
b. heat absorbed, entropy increases
c. heat increased, entropy decreases
d. heat released, entropy decreases
3) How much heat is required to convert 9.00g of water at 100*C into steam at 100*C, if the ∆Hvap=40.7kJ/mol?
4) How much energy is required to raise the temperature of 8.5g of water from 24*C to 29*C?
5) Write an equilibrium expression for the following reaction: 2N2 + O2 --> 2N2O
6) Hydrogen and iodine react to form hydrogen iodide at an elevated temperature. H2 + I2 --> 2HI. What is the
value of the equilibrium constant if the concentrations are [H2] = [I2] = .00426M and [HI] = .0162M?
7) For an experiment, some hydrogen gas was collected by water displacement. The barometric pressure and
temperature during the experiment were 745 mm Hg and 24.5 *C, respectively. What was the partial pressure
of the hydrogen collected, if the vapor pressure of water at 24.5*C is 23.1 mm Hg?
8) You are standing on one side of a room when your friends equal distances away both open different bottles of
perfume. After a short while, you can smell one of the perfumes, and then a little while later you can smell a
combination of both. What statements can you make about what is occuring?
9) Use the kinematic theory of matter to explain why tire blow-outs are more common during the summer than
the winter. Also consider the state of the rubber and levels of friction on the driving surfaces.
10) How would you use LeChatelier’s principle to increase the products of the following reaction?
2A(g) + 3B --> 5C(g) + heat
11) What volume would 5 moles of H2 gas at 273*K and 50.5 kPa occupy?
12) How do intermolecular forces affect the energy required for a phase change from liquid to gas? Be as detailed
as possible in your description, including multiple types of intermolecular forces, examples of common fluids or
gases whose boiling point is affected by this, and background information on the states of matter, phase change,
and kinematic theory of matter.