Part A The rate of the reaction in terms of the \"disappearance of reactant\" in
ID: 1017008 • Letter: P
Question
Part A
The rate of the reaction in terms of the "disappearance of reactant" includes the change in the concentration of the reactant, the time interval, and the coefficient of the reactant.
Consider the following reaction:
2A+3B3C+2D
The concentrations of reactant A at three different time intervals are given. Use the following data to determine the average rate of reaction in terms of the disappearance of reactant A between time = 0 sand time = 20 s.
Express your answer in molar concentration per second to three significant figures.
Part B
The rate of the reaction in terms of the "appearance of product" includes the change in the concentration of the product, the time interval, and the coefficient of the product.
Consider the following reaction:
2A+3B3C+2D
The concentrations of product C at three different time intervals are given. Use the following data to determine the rate of reaction in terms of the appearance of product C between time = 0 s and time = 20 s .
Express your answer in molar concentration per second to three significant figures.
Part C
The rate of reaction in terms of the "rate law expression" includes the rate constant (k), the concentration of the reactants, and the orders of the reaction with respect to the different reactants.
Consider the following reaction:
A+BC+D
The initial concentrations of the reactants A and B are 0.320 M and 0.400 M, respectively.
The rate of reaction is 0.060 Ms1, and the orders of the reaction, with respect to reactants A and B, are 1 and 2, respectively.
Determine the rate constant (k) for the reaction using the rate law.
Express your answer in M2s1 to three significant figures.
Time (s) 0 20 40 [A](M) 0.1200 0.0720 0.0540Explanation / Answer
A. Rate of reaction = rate of disappearance of reactant = -1/2(?A/?t) [coefficient of A in reaction = 2]
?A = Af -Ai = (0.0720-0.1200) M = -0.0480 M [Af = final concentration after tf = 20 s, Ai = initial concentration after ti = 0 sec]
?t = tf - ti = (20 - 0) s = 20 s
Hence, rate = -1/2?A/?t = - 1/2 (-0.0480 M)/20 s = 1.200 * 10^-3 M s-1 = 1.20 * 10^-3 M s-1 upto 3 sig. figs)
B.
Rate of reaction = rate of appearance of product = 1/3(?C/?t) [coefficient of C in reaction = 3]
?C = Cf -Ci = (0.0720-0) M = 0.0720 M [Af = final concentration after tf = 20 s, Ai = initial concentration after ti = 0 sec]
?t = tf - ti = (20 - 0) s = 20 s
Hence, rate = 1/3 ?A/?t = 1/3 (0.0720 M)/20 s = 1.200 * 10^-3 M s-1 = 1.20 * 10^-3 M s-1 (upto 3 sig. figs)
C.
A+B?C+D
The initial concentrations of the reactants A and B are 0.320 M and 0.400 M, respectively.
The rate of reaction is 0.060 M?s?1, and the orders of the reaction, with respect to reactants A and B, are 1 and 2, respectively.
Hence, according to rate law --> rate = rate constant (k) * [A]^ m * [B] ^n [m =order with respect to A, n= order with respect to B]
i.e. rate = k * [A]^ 1 * [B] ^2
Considering initial concentrations and corresponding rate, the rate equation becomes
0.060 M?s?1 = k * (0.320 M) * (0.400 M)^2
Hence k = 0.060 M?s?1/ (0.320 M) * (0.400 M)^2 = 1.172 M?2?s?1 = 1.17 ?M?2?s?1 (upto 3 sig. figs)