Question

What are the hydronium and hydroxide ion concentrations in a
$3\times {10}^{-2}M$ NaOH solution?

• A. $\left[H_3{O}^{+}\right]=3.33\times {10}^{-13}M$
  $\left[O{H}^{-}\right]=3\times 10M$
• B. $\left[H_3{O}^{+}\right]=3\times {10}^{-2}M$
  $\left[O{H}^{-}\right]=3\times {10}^{-2}M$
• C. $\left[H_3{O}^{+}\right]=3.33\times {10}^{-13}M$
  $\left[O{H}^{-}\right]=3\times {10}^{-2}M$
• D. $\left[H_3{O}^{+}\right]=3.33\times {10}^{-13}M$
  $\left[O{H}^{-}\right]=3.33\times {10}^{-13}M$
• E. $\left[H_3{O}^{+}\right]=3\times {10}^{-4}M$
  $\left[O{H}^{-}\right]=3\times {10}^{-6}M$

Answer 1

The correct option is C $\left[H_3{O}^{+}\right]=3.33\times {10}^{-13}M$

$\left[O{H}^{-}\right]=3\times {10}^{-2}M$
$\left[O{H}^{-}\right]=\left[NaOH\right]=3\times {10}^{-2}M$
$\left[H_3{O}^{+}\right]=\frac{K_w}{\left[O{H}^{-}\right]}=\frac{1\times {10}^{-14}}{3\times {10}^{-2}}=3.33\times {10}^{-13}M$