Name: 
 

Rates Practice test



Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

Which statement does not represent a rate?
a.
The speed of a car is 45 km/h.
b.
The half-life of an element is 12.4 h.
c.
A family consumes 4 L of milk every three days.
d.
It takes 15 min to walk to the store.
e.
A cat eats three cans of wet food per week.
 

 2. 

Which expression does not represent the rate of the following reaction?
Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)
a.
mc002-1.jpg
b.
mc002-2.jpg
c.
mc002-3.jpg
d.
mc002-4.jpg
e.
All of these are accurate representations of the rate of this reaction.
 

 3. 

In the following reaction, butane is consumed at the rate of 0.0333 mol/(Ls). Determine the rate at which CO2 is produced.
C4H10(g) + mc003-1.jpgO2(g) 4CO2(g)  + 5H2O(g)
a.
0.008 25 mol/(Ls)
b.
0.0165 mol/(Ls)
c.
0.0333 mol/(Ls)
d.
0.0667 mol/(Ls)
e.
0.133 mol/(Ls)
 

 4. 

Given the following reaction mechanism, what is the equation for the overall reaction?
2A B + 2C (slow)
B + C D + E (fast)
C + D E + F (fast)
a.
2A 2E + F
b.
2A + B + 2C D + 2E + F
c.
2A + 2C 2E + F
d.
2A + B + 2C + D B + 2C + D + 2E + F
e.
2A + C 2E + F
 

 5. 

The isotope mc005-1.jpg has a half-life of 165 days. The isotope mc005-2.jpg has a half-life of 330 days.
Which statement about these two isotopes is false?
a.
One year represents slightly more than two half-lives of a sample of the calcium isotope.
b.
Almost all of 100 g of the calcium isotope will decay in one year’s time.
c.
100 g of the vanadium isotope will decay to somewhat less than 50 g in a year.
d.
The calcium isotope decays at twice the rate of the vanadium isotope.
e.
All of these statements are true.
 

Short Answer
 
 
For the following questions, write the most appropriate answer in the space provided.
 

 6. 

What is the order of the reaction with the rate law expression r = k[A]0[B]1?
 

 7. 

Use the collision theory to explain the rate at which gas reactions usually occur.
 

 8. 

The reactant concentration of a first-order reaction is 0.05 mol/L, and the rate constant is 0.25 s1. What is the rate of this reaction?
 

Problem
 
 
Graphics
For the following questions, use the graphics provided to review terms or skills. Add any missing labels, draw any missing parts, or use the graphics to help you answer a question.
 

 9. 

The following graph represents the concentration of H2O2(aq) over time for the decomposition of hydrogen peroxide into water.
2H2O2(aq) 2H2O(l) + O2(g)
      pr009-1.jpg
a) What would you do to determine the rate of reaction at A?
b) Compare the rate of reaction at A with the rate of reaction at B. Explain the difference in terms of the collision theory.
c) Sketch the general shape of the curve, showing the concentration of H2O versus time on the same graph.
 

 10. 

Use a Maxwell-Boltxmann diagram to help you explain why an increase in temperature results in an increase in the rate of reaction.
 

 11. 

Consider the following series of potential energy diagrams.
pr011-1.jpg
a) Which diagram represents the fastest reaction at room temperature? Explain your choice.
b) Which diagram represents the reaction of two solids at room temperature? Explain your choice.
 
 
Critical Thinking
For the following questions, write the answer in the space provided. Use complete sentences in your answer. If the question requires mathematical calculations, show all of your work. Write a final statement that gives your solution.
 

 12. 

Doubling the concentration of hydroxide ions in the following reaction causes the reaction rate to double. Doubling the concentration of both reactants causes the reaction rate to increase by a factor of four.
C2H5Br(aq) + OH(aq) C2H5OH(aq) + Br(aq)
a) What is the order of the reaction with respect to hydroxide ions?
b) What is the order of the reaction with respect to bromoethane?
c) What is the overall reaction order?
 
 
Applications
For the following questions, write the answer in the space provided. Use complete sentences in your answer. If the question requires mathematical calculations, show all of your work. Write a final statement that gives your solution.
 

 13. 

Why are catalysts important in industries? Give one example of an industrial catalyst.
 



 
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