Question

The rate constant of a zero order reaction is $2.0 \times 10^{-2}\, mol \,L^{-1}\, s^{-1}$. If the concentration of the reactant after $25$ seconds is $0.5\,M$. What is the initial concentration ?

• A. $0.5\,M$
• B. $1.25\,M$
• C. $12.5\,M$
• D. $1.0\,M$

Answer 1

Answer: (D)

$1.0\,M$

Answer 2

For a zero order reaction Rate constant $=k=\frac{a-x}{t}$ $2\times10^{-2}=\frac{a-0.5}{25} a=05=0.5$ $a= 1.0\,M$