College Chemistry Solutions/Kinetics Practice Problems
Write your answers and show your work on a separate sheet of paper.
1.
Define solute, solvent, solution, concentrated, dilute,
saturated, unsaturated, supersaturated, colligative,
dissociation.
2.
According to the graph to the right, how much KCl would
precipitate from a 90°C solution with 50 g/100gH2O as it is
cooled to 20°C?
3.
Would the following solution be saturated, unsaturated, or
supersaturated? You have a solution of NaCl with a
concentration of 30g/100g at 60°C.
4.
A solution of NaCl is 20% by mass. If you have 500 g of
solution, how much NaCl does it contain?
5.
Which of these will provide more ions if you have equal
molarity of them: NaCl or K2SO4 or are they the same?
6.
7.
What is the mass of HCl in 750 mL of 2.5 M HCl solution?
8.
You need 500 mL of 5M H2SO4. What volume of 6M H2SO4
must be dissolved in water to form this solution?
9.
How many grams of KCl (molar mass of 74.6) would be
needed to prepare 3 L of a 0.15 M solution?
Adding which of the following to 1.0 L of water would result
in a solution with the highest boiling point? 200 g NaCl, 200 g KCl, 100 g LiF
10. What is the boiling point of a mixture of 200.0g of water and 10.0g of KCl? Molar mass of KCl is
74.55g/mol. ∆TB = m x d.f. x kB kB H2O = 0.52°C/m
11. Increasing temperature increases reaction rate by what means?
12. Explain the role a catalyst plays in speeding up a reaction.
13. If you have a first order reaction and you double the concentration, the rate will ________?
14. If you have a third order reaction and you double the concentration, the rate will _________?
15. If you have a second order reaction and you cut the concentration by one-third, the rate will __________?
16. If a reaction rate decreases by a factor of one-sixteenth when a reactant concentration is decreased by onefourth, what is the order of the reaction with respect to that reactant?
17. In a first-order reaction, what is the rate constant if the rate is 0.400M/s and the reactant concentration is
0.300M?
18. In a second order reaction, what is the rate constant if the rate is 0.020M/s and the reactant concentration is
0.005M?
19. What is the rate of a first-order reaction that has a reactant concentration of 0.850M and a rate constant of
0.17 1/s?
20. Consider a reaction A + B + C  D
Trial
Initial Concentration (M)
Initial Rate
(M/s)
A
B
C
1
0.05
0.10
0.10
0.0035
2
0.05
0.20
0.10
0.0070
3
0.10
0.20
0.20
0.056
4
0.10
0.20
0.10
0.028
a) Write the rate law equation for this reaction
b) What is the overall rate order for this reaction?
c) Calculate the rate constant and show proper units.
College Chemistry Solutions/Kinetics Practice Problem Answers
1. Consult your chemistry book and notes
2. 17grams (goes down to a solubility of 33g/100g at 20°C, therefore if it started with 50grams the difference
between 50 and 33 is 17.)
3. Unsaturated (under the solubility curve)
4. 100g
5. K2SO4 because it will break into two K+1 ions and one SO4-2 ion (3 ions overall). NaCl would only produce 2 ions.
6. There are 1.875 moles HCl present, and HCl is 36.5 g/mol, therefore there must be about 68.4 g of HCl.
7. 0.45 mol x 74.6 g/mol = 33.6 g
8. 0.417 L (or 417 mL). Use M1V1=M2V2
9. LiF (produces about 3.8 moles (x2) compared to 3.4 moles (x2)for NaCl)
10. 100.70 °C
11. Increasing temperature means there is more energy. Particles with higher energy will collide more often
(moving faster) and will collide with higher energy. This leads to a greater likelihood that a bond-breaking
collision necessary for reaction will occur.
12. Catalysts lower the activation energy of the reaction by changing the reaction pathway. They do not change
the energy of the particles.
13. double
14. increase by a factor of 8
15. decrease by a factor of one-ninth
16. second order
17. 1.33 1/s
18. 8.0 x 102 1/sM
19. 0.14M/s
20. a) rate = k[A]2[B][C] (hint to determine rate orders: for A, use trials 2 to 4; for B use trials 1 to 2; for C use trials
4 to 3)
b) 4
c) k = 140 1/sM3