CHEM 120 Chapter 14 Exam Practice
Questions with verified answers
Consider the reaction:
2NO(g) + O2(g) ---> 2NO2(g)
Suppose that a particular moment during the reaction nitric oxide
NO is reacting at a rate of −0.018Ms.
1. Is molecular oxygen being produced or consumed?
2. At what rate is molecular oxygen reacting? Round your answer to
2 significant digits. (STEPS) - Correct answer 1. Molecular oxygen is being consumed
2. STEPS:
Give the rate expression
Multiply the given rate by the 1/2 or -1/2
Then determine pos or neg with the oxygen -1/2
answer: 9.0 X 10^-3 m/s
Enter the correct coefficients to complete the reaction rate expression in terms of the disappearance of
reactants and the appearance of products for the following equation:→
+5Cl−aq + ClO−3aq 6H+aq + 3Cl2aq 3H2Ol - Correct answer STEPS:
1. See how you are filling out rate expression.
2. Use coefficients to determine the 1/X.
3. ALL reactants are going to have a -1/X
4. ALL products will have a 1/X
answer: (the coefficients from left to right)
-1/5 = -1/1 = -1/6 = 1/3 (no H2O bc it's L)
Consider the reaction: X + Y→ Z
(there will be a chart with the "initial rate of disappearance of X" and then the second column will be [X]
(M) then the next column will be [Y] (M).)
, 1. From the data in the table, obtained at 360K ,determine the overall order of the reaction.
2. Determine the initial rate of disappearance of X when the concentration of X is 0.30M and that of Y is
0.20M. Round your answer to 2 significant digits. - Correct answer 1. STEPS:
Determine the order by using: c1/c2 and r1/r2 (add these to get overall order)
0.40/0.20= 2=x
0.60/0.60= 1=y
x+y= 2+1= 3
answer: 3
2. STEPS
Solve for K by using:
K= rate/[X]^x [Y]^y
K= 0.053/[0.30]^2 [0.20]^1= 10.6
Plug K into rate law expression and solve:
rate= K[X]^x [Y]^y
rate= (10.6) [0.30]^2 [0.20]^1= 0.1908 m/s
answer: 0.19 m/s
Determine the overall orders of the reactions to which the following rate laws apply:
1. rate=k[NO2]^2 [O2]
2. rate=k - Correct answer 1. STEPS
Add the exponents.
2+1=3
answer: reaction order=3
2. STEPS
Add the exponents
0+0=0
answer: reaction order=0
Cyclobutane decomposes to ethylene according to the equation:
Questions with verified answers
Consider the reaction:
2NO(g) + O2(g) ---> 2NO2(g)
Suppose that a particular moment during the reaction nitric oxide
NO is reacting at a rate of −0.018Ms.
1. Is molecular oxygen being produced or consumed?
2. At what rate is molecular oxygen reacting? Round your answer to
2 significant digits. (STEPS) - Correct answer 1. Molecular oxygen is being consumed
2. STEPS:
Give the rate expression
Multiply the given rate by the 1/2 or -1/2
Then determine pos or neg with the oxygen -1/2
answer: 9.0 X 10^-3 m/s
Enter the correct coefficients to complete the reaction rate expression in terms of the disappearance of
reactants and the appearance of products for the following equation:→
+5Cl−aq + ClO−3aq 6H+aq + 3Cl2aq 3H2Ol - Correct answer STEPS:
1. See how you are filling out rate expression.
2. Use coefficients to determine the 1/X.
3. ALL reactants are going to have a -1/X
4. ALL products will have a 1/X
answer: (the coefficients from left to right)
-1/5 = -1/1 = -1/6 = 1/3 (no H2O bc it's L)
Consider the reaction: X + Y→ Z
(there will be a chart with the "initial rate of disappearance of X" and then the second column will be [X]
(M) then the next column will be [Y] (M).)
, 1. From the data in the table, obtained at 360K ,determine the overall order of the reaction.
2. Determine the initial rate of disappearance of X when the concentration of X is 0.30M and that of Y is
0.20M. Round your answer to 2 significant digits. - Correct answer 1. STEPS:
Determine the order by using: c1/c2 and r1/r2 (add these to get overall order)
0.40/0.20= 2=x
0.60/0.60= 1=y
x+y= 2+1= 3
answer: 3
2. STEPS
Solve for K by using:
K= rate/[X]^x [Y]^y
K= 0.053/[0.30]^2 [0.20]^1= 10.6
Plug K into rate law expression and solve:
rate= K[X]^x [Y]^y
rate= (10.6) [0.30]^2 [0.20]^1= 0.1908 m/s
answer: 0.19 m/s
Determine the overall orders of the reactions to which the following rate laws apply:
1. rate=k[NO2]^2 [O2]
2. rate=k - Correct answer 1. STEPS
Add the exponents.
2+1=3
answer: reaction order=3
2. STEPS
Add the exponents
0+0=0
answer: reaction order=0
Cyclobutane decomposes to ethylene according to the equation:
