Question

A first order reaction is 20% complete in 10min. The specific rate constant is:

• A. 0.0223 $mi{n}^{-1}$
• B. 0.0423 $mi{n}^{-1}$
• C. 0.0501 $mi{n}^{-1}$
• D. 0.0517 $mi{n}^{-1}$

Answer 1

Answer: (A)

0.0223 $mi{n}^{-1}$

A first order reaction is 20% complete in 10min.
The expression for the specific rate constant is $k=\frac{2.303}{t}\log \frac{a}{(a-x)}=\frac{2.303}{10}\log \frac{100}{(100-20)}=0.0223mi{n}^{-1}$.