Question

The number of $H_3{O}^{+}$ ions present in 10ml of water at ${25}^{\circ }C$ is:

• A. $6.023\times {10}^{-14}$
• B. $6.023\times {10}^{14}$
• C. $6.023\times {10}^{-19}$
• D. $6.023\times {10}^{19}$

Answer 1

The correct option is B $6.023\times {10}^{14}$

No. of hydronium ions present in $10$ml water at ${25}^{0}C$.

$pH=7$ at ${25}^{0}C$

$\left[H^{+}\right]={10}^{-7}M$

No. of moles $=$ Concentration $\times$ Volume

$=\left({10}^{-7}\right)\left(10\right)\times {10}^{-3}$

$={10}^{-9}$moles

1 mole has $6.023\times {10}^{23}$ ions of hydronium.

$\Rightarrow 6.023\times {10}^{23}\times {10}^{-9}$ ions in $10$ml water

$\Rightarrow 6.023\times {10}^{14}$ ions are there in $10$ml water at ${25}^{0}C$.

Hence, option B is correct.