Question

1) Consider the following equation: Rate = k [CH₃I]² [C₁₅H₁₁N]

i) If the concentration of C₁₅H₁₁N is doubled, does the rate constant:

A) Increase

B) Decrease

C) Remain unchanged

ii) If the concentration of of CH₃I is decreased by a factor of 3, the time it takes for the reaction to finish will:

A) Increase by a factor of 3

B) Increase by a factor of 9

C) Decrease by a factor of 9

D) Remain Unchanged

iii) If the temperature increases how will the activation energy change:

A) It will increase

B) It will decrease

C) It will remain unchanged

2) During a titration of a weak acid with a strong base you add an additional small amount of base after reaching the equivalence point.

i) How does the pH of the solution change?

A) Increase

B) Decrease

C) Remain unchanged

ii) How does the K_a of the acid change?

A) Increase

B) Decrease

C) Remain unchanged

Answer 1

i. Rate = k [CH₃I]² [C₁₅H₁₁N]

[C₁₅H₁₁N] = 2[C₁₅H₁₁N]

Rate = k [CH₃I]² 2[C₁₅H₁₁N]

Rate = 2k [CH₃I]² [C₁₅H₁₁N]

rate is double

Rate constant does not depends upon concentration.

C) Remain unchanged

ii.

the concentration of of CH₃I is decreased by a factor of 3

Rate = k [CH₃I]² [C₁₅H₁₁N]

[CH3I]   = [CH3I]/3

Rate = K[CH3I]^2/9[C15H11N]

C) Decrease by a factor of 9

iii) If the temperature increases how will the activation energy change:

Temperature is directly proportional to activation energy.

A) It will increase

2. i. C) Remain unchanged

ii. Ka value is increases acid strength is increases.

A) Increase