Chemistry 12
Unit 3 Review
Page |1
Chem 12: Chapters 13, 10, 11, 12, 14
Unit 3 Worksheet
1.
What is miscible? Immiscible?
Miscible: two or more substances blend together for form a solution (water and
alcohol). Like polarities will blend to make a solution.
Immiscible: two or more substances create layers when added together (oil and
vinegar). Nonpolar and polar substances generally do not blend into solutions.
2.
What is saturated? Unsaturated? Supersaturated?
Saturated solution: holds the maximum solute, no more will dissolve
Unsaturated solution: more solute can still be added
Supersaturated solution: unstable solution has more than the maximum solute.
Any disturbance will cause the excess solute to come out.
3.
How does Temperature affect a) the solubility of a gas in an aqueous solution? b)
Solubility of a solid in aqueous solution.
Generally the solubility of gas solutes in water decrease at higher temperatures
Generally the solubility of solid solutes in water increase at higher temperatures
4.
How does Pressure affect the solubility of a gas in an aqueous solution?
Solubility of gas in water increases as the pressure of that gas above the liquid
increases.
5.
a) Will I2 or CH2Cl2 be more soluble in water? Explain. b) Which (CO2 gas in water
or KCl solid) is expected to be more soluble at higher temperatures c) Will CO2 gas
be more soluble in water when the container is pressurized with air or carbon
dioxide?
a) CH2Cl2, water and this are both polar.
b) KCl
c) Pressurized with CO2
6.
For a solution is made adding together 12.0 g of KNO3 and 70.0 grams of water.
The density of the resulting solution is 1.08 g/ml. Solve for the mass %, Molarity,
and molality.
Mass percent:
mass % =
x 100% = 14.6%
Molarity:
M=
= 1.57 M
molality:
m=
= 1.70 m
Chemistry 12
Unit 3 Review
Page |2
7.
Describe both quantitatively and qualitatively how you can prepare 300 ml of 2.00
M HCl solution from concentrated 12.0 M HCl solution.
M1V1 = M2V2
require 50.0 ml of 12 M HCl and water
In a container add about 200 ml of water, then 50.0 ml of 12 M HCl, mix and add
more water until the total volume comes to 300 ml total
8.
Solve for the grams of potassium nitrate in 40.5 grams of 14.8 % KNO3 solution.
5.99 g KNO3
9.
Calculate the molarity of a solution prepared by dissolving 5.72 grams of NaOH in
43.8 ml of solution.
3.26 M NaOH
10.
How many moles of NH4NO3 must be dissolved in 250 ml of solution to prepare a
0.452 M NH4NO3 solution?
0.113 mol NH4NO3
11.
If you evaporate to dryness all the water from a 450 g solution of 8.00% NaCl, how
many grams of NaCl will remain?
39.0 g NaCl
12.
A solution is produced by dissolving 6.75 grams of Ca(NO3)2 in water to produce
375 ml of solution that has a density of 1.03 g/ml. Calculate the mass percent of the
Ca(NO3)2 in the solution.
1.75% Ca(NO3)2
13.
What is osmosis?
Osmosis is the flow of a solvent from a less concentrated solution to a more
concentrated solution in the attempt to equal the two concentrations.
Osmotic pressure is the pressure required to stop an osmotic flow.
14.
What is the boiling point of an aqueous solution that is 5.00 m? The normal boiling
point of water is 100˚C, Kb for water = 0.512 ˚C.kg/mol.
102.56˚C
Chemistry 12
Unit 3 Review
Page |3
15. Complete the following table for the indicated substances.
substance
SiF4
CO3-2
C2H4O
Draw the best
3 resonances
2 structural
Lewis
isomers
structure(s),
resonances, and
structural
isomers if any
with octet
name electronic tetrahedral
geometry
around central
atom
name molecular tetrahedral
geometry
around central
atom
a)show 3-D
sketch with
atoms & bonds
in it
b) Indicate
polar bonds
with dipole
arrows toward
the more
electronegative
give all bond
109.5
angles
is it an ionic
nonpolar
compound,
polar or
nonpolar
molecule or an
ion?
Trigonal planar
K2SO3
2 [K]+1
and SO3-2 as
trigonal
pyramidal
Trigonal planar
around each C
tetrahedral
around O
Tetrahedral
around C, trigonal
planar around C
Trigonal planar Trigonal planar
around each C
bent around O
Tetrahedral
around C, trigonal
planar around C
Tetrahedral for
SO3-2
120
<109.5
ion
120, <109.5
109.5, 120
Polar
Polar
Trigonal
pyramidal for
SO3-2
ionic
Chemistry 12
Unit 3 Review
Page |4
16.
What is stronger (single, double, triple) bond? What is longer? single
17.
Using the Valence Shell Electron Repulsion (VSEPR) theory, fill in the angles for the
number of Electron Regions (2) 180˚
(3) 120˚ (4) 109.5˚
18. Fill in the following tables: VSEPR drawings
#of
number of electronic molecular bond angles rough
electron
bonded
geometry geometry
3-D
regions
atoms
name
name
sketch
O=C=O
an example
molecule or
ion
2
2
linear
linear
180
CO2
4
2
tetrahedral
bent
109.5
H2O
3
3
Trigonal
planar
trigonal
planar
120
SO3
19.
What is the volume of 32.7 grams of F2 gas at STP? 19.3 L
20.
What is the number of moles of gas in a 550 ml container at 30.0°C and 751 torr
pressure? 0.0218 mol
21.
534 mL of CH4 gas was collected at 23°C and 754 torr. What new volume would the
CH4 gas occupy at 732 torr and 46°C? 593 ml
22.
127 ml of N2 gas was collected by displacement of water at 25°C and 742 torr. What is
the number of moles of N2 gas? (The vapor pressure of water at 25°C is 24 torr.)
4.90 x 10-3 mol
23.
What pressure will 4.15 g of CO2 gas have when placed in a 320 mL container at
45.0°C? 7.69 atm
24.
Nitrogen gas is placed into a steel tank until its pressure is 21.4 atm at 20°C. The
maximum pressure the tank can safely contain is 50.0 atm. What is the highest
temperature in °C that this tank be safely heated? 411°C
25.
a)
b)
26.
Balance the following unbalanced equation:
C5H12 (g) +
8O2 (g) 
5CO2 (g) +
6H2O (g)
What volume of CO2 gas at STP will be produced from 144 g of C5H12? 156 L
3 H2 (g) + N2 (g)  2NH3 (g) all gases at same temperature and
pressure. How many cubic centimeters of H2 gas are required to produce 200 cm3 of
ammonia gas? 300 cm3 H2
Balance
Chemistry 12
Unit 3 Review
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27.
A vessel with an internal volume of 10.0 L contains 7.00 g of nitrogen gas (N2), 1.00 g of
Helium gas (He), and 3.20 g of oxygen gas (O2). At 25 °C, what is the partial pressure
from each substance and what is the total pressure inside the vessel?
0.250 mol N2, 0.250 mol He, and 0.100 mol O2; total moles = 0.600 mol
0.611 atm N2, 0.611 atm He, and 0.245 atm O2; total pressure = 1.47 atm
28.
A 450 ml sample of nitrogen gas at 21 °C and 0.987 atm is heated and expands to 9.00 L
at a new pressure of 75.0 torr. What is the final temperature in °C
588 K = 315 °C
29.
What are characteristics of an ideal gas according to the kinetic molecular theory?
Assumptions for the KMT…
1. An ideal gas consists of tiny particles in constant, random, straight-line motion.
2. Particles exhibit no attraction or repulsion between each other. Collisions of
gas particles are elastic.
3. There is a lot of space between particles. The volume of the particles
themselves is negligible compared to the total volume of the gas.
4. The speed of particles increases with increasing temperature. The average
kinetic energy of gas particles is proportional to the Temperature in Kelvin.
It is recommended to check the air pressure in your car tires when they are cold, not after
driving a great distance when they are warm. Explain what kind of pressure reading
difference one can expect.
After driving the temperature of the tires increase and that will increase the tire
pressure.
30.
31.
A gas is collected over water at a certain temperature. The total pressure is 747 torr. The
vapor pressure of water at this temperature is 22 torr. What is the partial pressure of the
dry gas collected?
725 torr
32.
Balance the following unbalanced equation:
C6H12O6 (s) + 6 O2 (g)  6 CO2 (g) + 6 H2O (g)
From the 75.0 g of O2 and 35.0 g of C6H12O6, determine how much carbon dioxide can
theoretically be produced in units of moles, liters at STP, and grams of CO2? Which is
the limiting reactant?
75.0 g O2 can produce
2.34 moles of CO2
35.0 g C6H12O6 can produce
1.17 moles of CO2
Limiting reactant is the sugar, C6H12O6
1.17 moles CO2, 26.1 L O2 at STP, 51.3 g CO2
Chemistry 12
33.
Unit 3 Review
Page |6
Fill in the term for each definition or description:
Hydrogen bonding A special kind of strong dipole-dipole attraction which occurs among
molecules when a H atom is bonded to a highly electronegative atom such as
N, O, or F.
Intermolecular force Forces between molecules
Molarity
A unit of concentration that measures mole solute per liter solution
Normal boiling pt The temperature point at which the vapor pressure of a liquid is equal to the
normal atmospheric pressure of 760 torr or 1 atm.
pH
A scale used to quantitatively measure the acidity or basicity of an aqueous
solution.
34.
What type of intermolecular bonds will the following have? (draw Lewis structures to
help visuallize)
(a)-dipole-dipole attraction, (b)-hydrogen bonding, (c)-London dispersion forces
B H2O
B HF
C CH4
C Br2
B NH3
A HI
35.
The vapor pressure at 20°C is given for the following substances:
H2O 17.5 torr and
Br2 173 torr
a)
Which liquid is more volatile? Br2 173 torr
b)
What type of intermolecular forces does each of these have?
H2O hydrogen bonding and Br2 London Dispersion Forces
c)
Explain why the difference in vapor pressure at 20°C makes sense.
Weaker attraction forces found in Br2 will cause the substance to have a higher
vapor pressure, more liquid molecules will have the required energy to escape the
attractions and become gas.
36.
a) Finish and balance the following acid / base reaction:
HC2H3O2 (aq) +
NaOH (aq)  NaC2H3O2 (aq) + H2O (l)
Acid (HC2H3O2)-------------------- -conjugate base (C2H3O2-1)
Base (OH-1)-----------------------conjugate acid (H2O)
b) For the above balanced equation, label and draw lines connecting the acid and its
conjugate base, and the base and its conjugate acid.
c) A titration starts with 25 ml of 0.42 M HC2H3O2, acetic acid, solution. 42.5 ml of
NaOH solution are then added to neutralize the solution. Calculate the moles of HC 2H3O2
initially, the moles of NaOH used, and the molarity of the NaOH solution.
0.0105 moles of HC2H3O2 , 0.0105 moles of NaOH used, 0.247 M NaOH
Chemistry 12
37.
38.
Unit 3 Review
A KOH solution is standardized using KHP. Using the following titration data, calculate
the molarity of the KOH solution. (the molecular weight of KHP is 204.2g/mol)
KOH buret readings:
final
32.65 ml
mass of flask + KHP
144.301 g
initial 12.73 ml
mass of empty flask
143.422 g
used
19.92 ml KOH
mass of KHP
0.879 g
0.216 M KOH
Given the following pH values label each as acidic, basic or neutral.
pH = 7 neutral
39.
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pH = 3 acid
pH = 9 base
pH = 0.5 acid
Fill in the missing pieces of this table
acid, base,
or neutral?
[H+]
[OH-]
pH
pOH
Base
7.2 x 10-12
1.4 x 10-3
11.14
2.86
Neutral
1.0 x 10-7
1.0 x 10-7
7.0
7.0
Base
2.5 x 10-9
4.0 x 10-6
8.6
5.4
Base
3.2 x 10-11
3.2 x 10-4
10.5
3.5
Acid
2.0 x 10-4
5.0 x 10-11
3.7
10.3
Kw = 1.0 x 10-14 = [H+1][OH-1]
pH = -log[H+1]
[H+1] = 10-pH
pOH = -log[OH-1]
[OH-1] = 10-pOH
pKw = -log[Kw]
pKw = pH + pOH = 14
Acid has a pH < 7
Neutral has pH = 7
Base has a pH > 7
Chemistry 12
40.
Unit 3 Review
Page |8
Circle the letters of the following which are not a conjugate acid-base pair. Circle the
acid and underline the base for each conjugate acid-base pair.
a) HCl, Cl-
b) Cl-, ClO4-
e) NH3, NH4+
f) H2O, H3O+
c) H3PO4, PO4-3
d) H2SO4 , HSO4-
41.
Answer the following as true or false. For the false statements what must be changed to
make them true?:
F
A solution is a homogeneous mixture which can only be found in the liquid state.
T
A buffered solution resists change in its pH even when a strong acid or base is
added.
F
A buffered solution always contains a strong acid and its conjugate base.
F
A weak acid will completely dissociate in water.
F
A combination of HCl and NaCl would make a good buffer solution
T
A combination of HCN and KCN would make a good buffer solution.
T
An amphoteric substance can act as either an acid or a base
T
An acid-base reaction is often called a neutralization reaction because the acid and
base are neutralized by creating water.
F
If more solute is added to a solution that is saturated, that solute will dissolve and
make the solution more concentrated.
F
When an ionic solution such as NaCl dissolves in water, the NaCl molecules stay
attached to each other.
F
It is possible to have an aqueous solution with 0.0007 M [H+] and 0.0000003 M
[OH-]
F
Cl- is the conjugate acid of HCl.
T
A pipet will deliver a specified amount of liquid with great accuracy.
42.
30.0 ml of 0.240 M NaOH is required to stoichiometrically react with 20.0 ml of HCl
solution. Write the balanced acid-base equation and calculate and Molarity of the HCl
solution?
HCl (aq) + NaOH (aq)  H2O (l) + NaCl (aq)
0.360 M HCl