Tentukan pH larutan di bawah ini:
(A) \(\ce{HNO3}\) 0,05 M
(B) 0,98 gram \(\ce{H2SO4}\) dalam 10 mL larutan
Ar H = 1, O = 16, S = 32
(A) \(\ce{HNO3}\) 0,05 M
Konsentrasi \(\ce{H+}\)
\begin{array}{ccccc}
\ce{HNO3(aq) & -> & H+(aq) & + & NO3^{-}(aq)} \\
{\color{red}0,05} & & {\color{red} 0,05} & & {\color{red}0,05}
\end{array}
pH larutan
\begin{equation*}
\begin{split}
\text{pH} & = - \log [\ce{H+}] \\\\
\text{pH} & = - \log [0,05] \\\\
\text{pH} & = - \log \left[ 5 \:.\: 10^{-2} \right] \\\\
\text{pH} & = 2 - \log 5
\end{split}
\end{equation*}
(B) 0,98 gram \(\ce{H2SO4}\) dalam 10 mL larutan
Konsentrasi \(\ce{H2SO4}\)
\begin{equation*} \begin{split} \text{n} & = \frac {\text{gr}}{\text{Mr}} \\\\ \text{n} & = \frac {0,98}{2 \:.\: 1 + 32 + 4 \:.\: 16} \\\\ \text{n} & = \frac {0,98}{98} \\\\ \text{n} & = 0,01 \text{ mol} \end{split} \end{equation*}
\begin{equation*} \begin{split} \text{M} & = \frac {\text{n}}{\text{V}} \\\\ \text{M} & = \frac {0,01}{0,1} \\\\ \text{M} & = 0,1 \end{split} \end{equation*}
Konsentrasi \(\ce{H+}\)
\begin{array}{ccccc}
\ce{H2SO4(aq) & -> & 2H+(aq) & + & SO4^{2-}(aq)} \\
{\color{red}0,1} & & {\color{red} 0,2} & & {\color{red}0,1}
\end{array}
pH larutan
\begin{equation*}
\begin{split}
\text{pH} & = - \log [\ce{H+}] \\\\
\text{pH} & = - \log [2 \:.\: 0,1] \\\\
\text{pH} & = - \log \left[ 2 \:.\: 10^{-1} \right] \\\\
\text{pH} & = 1 - \log 2
\end{split}
\end{equation*}