Chem 116 Week 7 Parte Chemical Kinetics

Consider the following gas-phase reaction, 2HI(g) → H2(g) + I2(g), and the following experimental data obtained at 555 K: [HI], M | rate, M s^-1 0.0500 | 8.80 x 10^-10 0.1000 | 3.52 x 10^-9 0.1500 | 7.92 x 10^-9 What is the order of the reaction with respect to HI(g)?

Laughing gas, N2O, can be prepared from H2 and NO: H2(g) + 2NO(g) → N2O(g) + H2O(g) A study of initial concentration versus initial rate at a certain temperature yields the following data for this reaction: [H2], M | [NO], M | initial rate, M s^-1 0.1000 | 0.5000 | 2.560 x 10^-6 0.2000 | 0.3000 | 1.843 x 10^-6 0.1000 | 0.3000 | 9.216 x 10^-7 0.2000 | 0.6000 | 7.373 x 10^-6 Which of the following is the correct rate law for this reaction?

• Rate = k[H2][NO]^2

• Rate = k[H2][NO]

• Rate = k[NO]^2

• Rate = k[H2]^2

• Rate = k

Which of the following rate laws is consistent with these data?

• Rate = k[NO]

• Rate = k[NO][Cl2]½

• Rate = k[NO][Cl2]

• Rate = k[NO]²[Cl2]

• Rate = k[NO]²[Cl2]²

What is the OVERALL order of the reaction of NO with Cl2?

• 1

• 1.5

• 2

• 3

• 4

What is the value of the rate constant for the reaction of NO with Cl2?

• 2.38

• 3.35

• 4.76

• 9.52

• 19.04

Consider the following reaction in aqueous solution, I(aq) + OCl^-(aq) → IO(aq) + Cl^-(aq), and the following initial concentration and initial rate data for this reaction: Which of the following is the correct rate law for this reaction?

• Rate = k[I]

• Rate = k[OCl^-]

• Rate = k[I]^2

• Rate = k[I][OCl^-]

• Rate = k[I]^2[OCl^-]

The rate of the reaction NO2(g) + CO(g) → NO(g) + CO2(g) depends only on the concentration of NO2 below 225°C. At a temperature below 225°C, the following data were obtained: Calculate the value of the rate constant, k, for this reaction.

• 8 x 10^-6

• 2 x 10^-5

• 3 x 10^-5

• 1 x 10^-4

• 2 x 10^-4

Iodine-131, a radioactive isotope of iodine, is used medicinally as a radiotracer for the diagnosis and treatment of illnesses associated with the thyroid gland. The half-life of iodine-131 is 7.0 x 10^5 seconds. If a patient is given 0.45 g of iodine-131, calculate how long it would take (in seconds) for 90.0% of the iodine-131 to decay. Recall: radioactive decay is a first-order process.

Radioactive phosphorus is used in the study of biochemical reaction mechanisms. The isotope, phosphorus-33, decays by first-order kinetics with a half-life of 14.3 days. If a chemist initially has a 7.5 M solution of pure phosphorus-33, calculate the concentration (in M) of phosphorus-33 in the solution after 2.4 days.

A decomposition reaction involving a single reactant has a rate constant, k, equal to 0.066 s^-1. Calculate the time required (in seconds) for the concentration of the reactant to reach 19.4% of its initial value.

• 3.3 s

• 12 s

• 25s

• 44 s

• 63 s