Question

2 H2O2(aq) + 2 H2O(l) + O2(g) 5. Hydrogen peroxide decomposes according to the equation above. a. An aqueous solution of H2O, that is 6.00 percent H,O, by mass has a density of 1.03 g ml. Calculate each of the following. (i) The original number of moles of H2O, in a 125 ml sample of the 6.00 percent H2O2 solution (ii) The number of moles of O,(g) that are produced when all of the H2O2 in the 125 mL sample decomposes b. The graphs below show results from a study of the decomposition of H2O2. 0.00 1.00 0.80 Гон) 0.60+ 0.40 0.20 0 800 3.200 0 800 3.200 1.600 2.400 Time (min) 1.600 2.400 Time (min) (i) Write the rate law for the reaction. Justify your answer. (ii) Determine the half-life of the reaction. (iii) Calculate the value of the rate constant, k. Include appropriate units in your answer. (iv) Determine (H2O2) after 2,000 minutes elapse from the time the reaction began. 6. The reaction between NO and Hy is believed to occur in the following three-step process. NO + NO + N2O2 (fast) NO, + H2 → NO + H2O (slow) N2O + H2 - N2 + H2O (fast) (a) Write a balanced equation for the overall reaction. (b) Identify the intermediates in the reaction. Explain your reasoning. (c) From the mechanism represented above, a student correctly deduces that the rate law for the reaction is rate = K[NO] [Hal. The student then concludes that (1) the reaction is third-order and (2) the mechanism involves the simultaneous collision of two NO molecules and an H2 molecule. Are conclusions (1) and (2) correct? Explain. (d) Explain why an increase in temperature increases the rate constant, k, given the rate law in (c).

Answer 1

$ u 24,02 7 2420 + 02 (8) volume of salution = 125 ml density = 1.03 ani moss of solution - Valume x density 125 X 1.03 = 128.75 gm Mass percent of hor = 6 = moss z mass moss of H2O2 = 6 x 128.75 of H2O2 x 100 as salition 7.73 sm maly of H2O2 = moss malor mor - 7.73 = 0.227 mals. 34 on - felis - 2 decomposition mal of hon i mal of H2O2 produce produce a mal of Oz ļmal of oz 0.227 mal of Ho produc 0.227 2 od mal of Oz = 0.1135 mal of Oz

O A dlot of In [hozd line. This suggest that tirst order. us t reaction give is a straight of Is [4202] = In Cholo - kt. Slope of straight line = rate constant (i) Rate law & R = K[H2O2] W halt like time a Time in which conch of M202 remain halt from its initial value {1-10.5] raat te= 600 min K 0.693 u= 0.693 600 min = 1016 X103 min after t = 2000 min In [42027= In [7.07. ht [H202) 6 = 1 In [h202] = dn [H2O2] = [hhor] = - 20000 1 -168163 -2.32 p*-2.32 = 0.098