Question

1. water auto - ionizes according to the following equation:

h₂o(l) → h¹⁺(aq) + oh¹⁻(aq)
measurements show that every 1.00 l of pure water contains 1.0 x 10⁻⁷ moles of ionized protons. what is the numerical percent composition of h¹⁺(aq) in a liter of water?

Explanation:

Step1: Calculate the molar mass of water

The molar mass of \(H_2O\) is \(M=(2\times1 + 16)\space g/mol=18\space g/mol\).
The mass of \(1.00\space L\) of water (density of water \(
ho = 1000\space g/L\)) is \(m=
ho\times V=1000\space g\).
The number of moles of water \(n=\frac{m}{M}=\frac{1000\space g}{18\space g/mol}\approx55.56\space mol\).

Step2: Calculate the percent composition

The formula for percent composition is \(\text{Percent Composition}=\frac{\text{Moles of }H^{+}}{\text{Moles of }H_2O}\times100\%\).
Substitute the values: \(\text{Percent Composition}=\frac{1.0\times 10^{-7}\space mol}{55.56\space mol}\times100\%\).

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Answer:

\(1.8\times 10^{-7}\%\)