A zero-order reaction has a rate constant of 0.33 Mmin-1. It takes ____ seconds

Question

A zero-order reaction has a rate constant of 0.33 Mmin-1. It takes ____ seconds for the reactant concentration to decrease from 0.23 M to 0.058 M.
a) 0.52 b) 39 c) 31 d) 4.2 e) 0.96

The rate constant for a second-order reaction is 0.130 M-1 s-1. If the initial concentration of reactant is 0.284 mol/L, it takes 12.98 s for the concentration to decrease to ___ mol/L.
a) 0.683 b) 2.734 c) 5.54 d) 0.479 e) 0.192

The rate constant of a first-order process that has a half-life of 0.554 s is ___ s-1.
a) 3.08 x 10^-3 b) 12.5 c) 1.25 d) 4.44 x 10^-3 e) 0.693

Explanation / Answer

Q1.

Apply

A0 = A + kt

0.23 =0.058 + 0.33*t

t = -(0.058 -0.23 )/0.33 = 0.5212 min = 0.5212 *60 s = 31.27 s

Q2.

for 2nd order

apply

1/A = 1/A0 + kt

1/(A) = 1/(0.284 ) + 0.13*12.98

A = (1/(0.284 ) + 0.13*12.98)^-1 = 0.191992 M

choose E

Q3.

1st order

ln(A)= ln(A0) - kt

for half life A = 1/2*A0

so

t 1/2 = ln(2)/k

k = ln(2)/(0.554) = 1.251 1/s

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