AP Chemistry Chapter 5

5H2O2 (aq)+ 2MnO4- (aq) + 6H+(aq) -- 2Mn2+ (aq) + 8H2O(l) + 5O2(g) In a titration experiment, H2O2(aq) reacts with aqueous MnO4-(aq) as represented by the equation above. The dark purple KMnO4 solution is added from a buret to a colorless, acidified solution of H2O2(aq) in an Erlenmeyer flask. At a certain time during the titration, the rate of appearance of O2(g) was 1*10^3 mol/(L*s) What was the rate of disappearance of MnO4- at the same time

4 * 10-4

If 87.5 percent of sample of pure 13th I decays in 24 days, what is the half- life of 131 I?

8 days

C2H4(g) + H2(g) -> C2H6(g) Which of the following will most likely increase the rate of the reaction represented above?

Adding a heterogeneous catalyst to the reaction system

CI- (aq)+ CIO-(aq) +2H+(aq) -- CI2(g) + H2O(l) what effect will increasing [H+] at constant temperature have on there reaction represented above?

The frequency of collisions between H+（aq) ions and CIO-(aq) ions will increases

S2O8 2- (aq) + 3I- (aq) -- 2SO4 2- (aq) + I3- (aq) In aqueus solution, the reaction represented by the balanced equation shown above has the experimentally determined rate law: rate = k [S2O82-] [I-] If the concentration of [S2O82-] is doubled while keeping [I-] constant, which of the following experimental results is predicted based on the rate law, and why

The rate of reaction will double, because the rate is directly proportional at [S2O82-]

2N2O5 (g)-- 4NO2(g) + O2(g) A sample of N2O5 was placed in an evacuated container, and the reaction represented above occurred. The value of Pn2o5, the partial pressure of N2O5(g), was measure during the reaction and recorded in the table below

the decomposition of N2O5 is a first-order reaction

2NO(g) + O2(g)-- 2NO2(g) Consider the following mechanism for the reaction represented above. Step 1: 2NO-- N2O2 (fast reversible) Step2: N2O2 + O2 -- 2NO2(slow)

the rate law that is consistent with the mechanism is rate= k[NO]^2 [O2]

H3AsO4 + 3I- + 2H3O+ -- H3AsO3 + I3- + H2O The oxidation of iodide ions by arsenic acid in acidic aqueous solution occurs according to the stoichiometry shown above. The experimental rate law of the reaction is Rate= K[H3AsO4] [I-] [H3O+] What is the order of the reaction with respect to I-?

1

Rate= K[M][N]^2 The rate of a certain chemical reaction between substances M and N obeys the rate law above. The reaction is first studies with [M] and [N] each 2*10^-3 molar, the reaction rate will increase by a factor of

8

When the chemical reaction 2NO(g) + O2(g) -- 2NO2(g) is carried out under certain conditions, the rate of disappearance of NO(g) is 5* 10^-5 Ms*-1 What is the rate of disappearance of O2（g) under the same conditions

Because two molecules of NO are consumed per molecule of O2, the rate of disappearance of O2(g) is 2.5*10^-5 Ms^-1

A kinetics experiment is set up to collect the gas that is generate when a sample of chalk, consisting primarily of solid CaCO3. is added to a solution of ethanoic acid, CH3COOH. The rate of reaction between CaCO3 AND CH3COOH is determined by measuring the volume of gas generated at 25 degree and 1 atm as a function of time. Which of the following experimental conditions is most likely to increase the rate of gas production

Decreasing the particles size of the CaCO3 by grinding it into a fine powder

Factors that affect the rate of a chemical reaction include which of the following? I. Frequency of collisions of reactant particles II. Kinetic energy of collisions of reactant particles III. Orientation of reactant particles during collisions

I, II and III

2HBr (g) + O2(g) -- H2O2(g) +Br2 (g) Based on a kinetics study of the reaction represented by the equation above, the following mechanism for the reaction is proposed Step 1: HBr(g) + O2(g)-- HO2Br(g) slow Step 2: HO2Br(g) + HBr(g) -- 2HO2Br(g) fast Step 3: 2HO2Br(g) -- H2O2（g) + Br2(g) fast Which of following rate law is consistent with the proposed mechanism?

Rate= k [HBr] [O2]

2HO2(g) + H2O2(g) +O2(g) The reaction represented by the chemical equation shown above occurs in Earth's atmosphere. In an experiment [H2O] was moiitored over time and the data plotted as shown in the following graph. Based on the information, which of the following is the rate law expression for the reaction?

Rate= k[HO2]^2

An experiment was conducted to determine the rate law for the reaction A2(g) + B(g) - A2B (g) The table above shows the data collected. Based on the data in the table, which statement is correct

Since the rate law can be expressed as rate= k[A2][B], doubling the concentration of A2 and B will quadruple the rate of the reaction.

Which of the following represents the overall chemical equation for the reaction and the rate law for elementary step 2

The overall reaction is H2(g) + 2ICI(g) -- 2HCI(g) + I2(g) The rate law for step 2 is rate = k[HI][ICI]

Br2(g) + 2NO(g) -- 2NOBr(g) The reaction represented by the equation above has the following proposed mechanism. Step 1: NO(g) + Br2(g) -- NOBr2(g) fast equilibrium Step 2: NOBr2(g) + NO(g) -- 2NOBr（g) slow Based on the information, which of the following is the initial rate law for the reaction

rate= k [Br2] [NO]^2

NO2(g) + CO(g) -NO(g) + CO2（g) Step 1: 2NO2(g)-- NO(g) + NO3(g) slow Step 2: NO3(g) + CO (g) -- NO2(g) + CO2（g) fast Which of the following is the rate law for the overall reaction that is consistent with the proposed mechanism?.

rate= k[NO2] ^2

2A(g）+ B(g) -- 2C(g) When the concentration of substance B in the reaction above is doubled, all other factors being held constant, it is found that the rate of the reaction remains unchanged. The most probable explanation for this observation is taht

substance B is not involved in the rate-determined step of the mechanism, but is involved in subsequent steps

Two samples of Mg(s) of equal mass were placed in equal amounts of HCl(aq) contained in two separate reaction vessels. Particle representations of the mixing of Mg(s) and HCl(aq) in the two reaction vessels are shown in figure 1 and figure 2 above. Water molecules are not included in the particle representations. Which of the reactions will initially proceed faster and why?

the reaction in Figure 2, because more Mg atoms are exposed to HCI(aq) in Figure 2 than in Figure 1