SI: Chem 178
Exam 1 Review
Leader: Emily
th
Feb 10 and 12th, 2013
Concepts Review
Ch 13:
What are the three types of intermolecular forces that act in the formation of solutions?
Consider the Hsoln equation... what is it, and how do these fit in?
What are the signs of each of the components of the Hsoln equation? What is occurring at
each step? What does a + or – H value represent?
Define:
Saturated:
Unsaturated:
Supersaturated:
_________ dissolves ____________ (Consider polarity and intermolecular interactions.)
Gas solubility increases as pressure increases/decreases making this a
positively/negatively correlated relationship.
Does pressure affect solids or liquids forming solutions?
In LIQUID solutions, increasing temperature generally increases/decreases solubility.
In gaseous mixes/solutions, increasing temperature generally _____________ solubility.
What are the steps required to go from molarity to molality? How do you reverse these
steps to go back? (Write it both ways!) Which of these is affected by temp?
List ALL the ways solute concentration can be expressed. (HINT: There are 6, and one
we haven’t talk about as much…)
Colligative properties depend on… TYPES of molecules dissolved or
CONCENTRATION of molecules dissolved
Colligative Property #1: Vapor pressure lowering: How can this be explained in terms of
energy? What sort of system must it be- open or closed – for this property to be applied?
Colligative Property #2 Boiling Pt Elevation: What occurs during boiling? Use the terms
solvent-solvent interactions and solute-solvent interactions to discuss why boiling point
elevation occurs. What is an equation that expresses this interaction?
Colligative Property #3: Freezing Pt Depression: What must occur for a liquid to freeze?
How do solute particles affect this process? Consider how energy and temperature relate
in this case. Write down the equation for this relationship. Kf = Kb – True or False?
Colligative Property #4: Osmosis. Copy the picture given to you on the board. Draw an
arrow showing direction of WATER flow. Water flows from
________________________ concentration in osmosis. What is osmotic pressure?
Chapter 15
Write out the general equation for Kc in this equation: aA + bB   cC + dD What
chemical states are represented in this equation (it may be easier to consider what
DOESN’T appear in this equation.) Units?
A large Kc means the reaction is favoring PRODUCTS/REACTANTS.
A small Kc means there’s like a greater concentration of PRODUCTS/REACTANTS
Flipping an equation does what to its Kc? Doubling an equation does what to its Kc?
How can you relate Kc and Kp in equation?
Write out the Q “number line.” Do you draw arrows from Q to K or K to Q to help
determine which way it will go? What does/can Q tell us?
Le Chatelier’s Principle: Circle the things below that change Kc. For those that affect Kc
or Kp, write an expression that explains this. See p. 631 in the text.
Increase in pressure
Decrease in temperature
Increase in volume
Decrease in products/reactants
Addition of a catalyst
Increase of temperature
Chapter 16 – KNOW YOUR STRONG ACIDS AND BASES
Define: Arrhenius BaseBronsted –Lowry BaseArrhenius Acid-
Bronsted Lowry AcidIs HSO4- amphiprotic? What does that mean?
Write out the equation for Kw and its value as well as the values for [OH-] and [H+].
How can pH and pOH be related mathematically?
A strong acid has a _________ conjugate base.
Given H2O(l) + HA(aq)   H+(aq) + A-(aq) write out the Ka equation and define each
piece.
What is the equation for % ionization? Which part uses equilibrium concentration versus
initial? What is the % ionization of a strong acid?
#Probs
Chapter 13:
#16 Number from weakest to strongest.
H Bonding
Ion-Dipole
Dispersion Forces
#75 How many grams of ethylene glycol must be added to 1 kg to produce a solution that
freezes at -5 Deg C? Kf = 1.86 Deg C/m
What is the molality of a 1.04M glucose solution with a density of 1.03g/mL? (MM of
glu is 180.61g/mol.)
Chapter 15:
#59
CH4(g) + I2(g)   CH3I(g) + HI(g) Kp= 2.26x10^-4 @ 630K Initial partial pressures
of CH4 and I2 were 105.1torr and 7.96 torr, respectively. Calculate the PPs of products
and reactants at equilibrium.
#46
N2(g) + 3H2(g)   2NH3(g) Kp = 4.51x10^-5 @ 450 Deg C. With the following
combinations of reactants and products, indicate whether the reaction is at equilibrium or
if it will favor reactants/products.
a) 98 atm NH3, 45 atm N2, 55 atm H2
b) 57, 143, 0
c) 13, 27, 82
Chapter 16:
#29 Calculate H+ concentration for each of the following, mention whether it’s acidic
basic or neutral.
a) [OH-]=0.00045M
b) [H+]= 0.000067
c) [OH-] 100x more than [H=]
#38 Fill in the table:
[H+]
7.5x10^-3
[OH-]
pH
pOH
3.6X10^-10
8.25
5.70
Acidic? Basic?
#44 c What is the pH of a solution of 15 mL of 1M HClO4 diluted to ½ L?
#51 CH3CH(OH)COOH has 1 acidic H+. A 0.1M solution has a pH of 2.44. What is its
Ka and what is its % ionization?
HCOOH(aq) +H2O(l)   H+(aq) + HCOO-(aq)
pH=1.95 and molarity of HCOOH initially is 0.12M Find Ka.
0.5M Acetic Acid HC2H3O2 with a Ka of 1.8x10^-5 @ 25 Deg C. What are the
equilibrium concentrations of products and reactants?