Question

A drop of solution (volume = 0.050 mL) contains $6\times {10}^{-7}molof{H}_3{O}^{+}$ ions. If $H_3{O}^{+}$ions disappear at a constant rate of $6.0\times {10}^5$ mol $L^{-1}{S}^{-1}$, how long will take for the $H_3{O}^{+}$ ions in the drop to disappear ?

• A. $2.0\times {10}^{-2}s$
• B. $6.0\times {10}^{-6}s$
• C. $2.0\times {10}^{-8}s$
• D. $8.0\times {10}^{-8}s$

Answer 1

The correct option is C

$2.0\times {10}^{-8}s$

$|H_3{O}^{+}|=\frac{6\times {10}^{-7}\times {10}^3}{0.05};t=\frac{|H_3{O}^{+}|}{rate}=\frac{6\times {10}^{-4}}{0.05}/6.0\times {10}^5=2.0\times {10}^{-8}S$