A first order reaction is 20 % complete in 10 minutes. What is the specific rate constant for the reaction?

Question

A first order reaction is 20 % complete in 10 minutes. What is the specific rate constant for the reaction? (A) 0.0970 min.-1 (B) 0.009 min.-1 (C) 0.0223 min.-1 (D) 2.223 min.-1

Tardigrade Admin · Accepted Answer

a-x=(80/100)× a=0.8a, t=10 min. k=(2.303/t) log (a/a-x) =(2.303/10) log (a/0.8a) k=0.233 log (10/8)=0.2303(1-0.9030) =0.2303× 0.0970=0.0223 min.-1

Q. A first order reaction is $20%$ complete in $10$ minutes. What is the specific rate constant for the reaction?

$0.0970 min .^{- 1}$

$0.009 min .^{- 1}$

$0.0223 min .^{- 1}$

$2.223 min .^{- 1}$

$a - x = \frac{80}{100} \times a = 0.8 a$ , $t = 10 min$ .
$k = \frac{2.303}{t} l o g$ $\frac{a}{a - x}$ $= \frac{2.303}{10} l o g$ $\frac{a}{0.8 a}$
$k = 0.233 l o g$ $\frac{10}{8} = 0.2303 (1 - 0.9030)$
$= 0.2303 \times 0.0970 = 0.0223$ $min .^{- 1}$

Q. A first order reaction is 20% complete in 10 minutes. What is the specific rate constant for the reaction?

0.0970min.−1

0.009min.−1

0.0223min.−1

2.223min.−1