Question

6. For the reaction: C2H4Br2 3 KI C2H4+2 KBr + KI3 Initial rate data at 60 "C are 0.500 0.500 1.50 1.80 7.20 1.80 0.269 1.08 0.807 The rate law is A) rate-kKI B) rate-C2H4Br2l G) rate KI2 D) rate- kKIIC2H4Br2] E) rate kIKIIC2H4Br2 7. Choose the INCORRECT answer. The rate of a chemical reaction: A) usually is increased when the concentration of one of the reactants is increased B) is dependent on temperature C) may be increased by certain catalytic agents D) will be very rapid if the activation energy is large E) describes the rate of change in concentration of a reactant or product with time 8. The rate of a specific chemical reaction is independent of the concentrations of the reactants. Thus the reaction is A) first order in A B) second order C) first order in the product D) catalyzecd E) overall zero order 9. The rate constant for a first-order reaction is k -0.00073 s-1., Determine the percent of reactant that has decomposed after 500 s A) 65% B)57% C)37% D) 31% E) 43% 10. Substance A decomposes by a first-order reaction Starting initaly with lA)-2.00 M, afer 150 min (A)- 0.50 M. For this reaction what is ty2 A) 150 min B) 37.5 min C) 75.0 min D) 15.0 min E) 300 min Chemistry 101, Winter 2019 Problem Set 5 Page 2 of 4

Answer 1

Option (E) correct The rate is independent of the reactant concentration. The rate of these zero order reactions do not vary which increasing (or) decreasing reactants concentrations. This means that the rate of the reaction is equal to the rate constant r = k [A]^0 r = k [A^0] = 1 \r\n from (1) & (2) r = k [A]^x [B]^y A = [C_2 H_4 Br_3} middot r B = [kI]_r 0.269 = k [0.500]^x [1.80]^y (1) 1.08 = k [0.500]^x [7.20]^y (2) (2)/(1) = > 1.08/0.269 = k[0.500]^x [7.20]^y/k [0.500]^2 [1.80]^y 4^1 = 4^y y = 1 from eq (1) (3) r = k[A]^x [B]^y 0.269 = k[0.500]^x [1.80]^y (!) 0.807 = k[0.50]^x [1.80]^y (3) eq (3)/(1) = > 0.807/0.269 = k[1.50]^x [1.80]^y/k[0.500]^x [1.80]^y 3^1 = 3^x x = 1 therefore rate - kw r = k [A]^x [B]^y r = k[C_2 H_2 Br_2] [KI] option D correct