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What is the $\mathrm{pH}$ of $0.01 \mathrm{M}$ glycine solution? For glycine, $K_{a_1}=4.5 \times 10^{-3}$ and $K_{a_2}=1.7 \times 10^{-10}$ at $298 \mathrm{~K}$ ?
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The correct answer is:
6.1
$$
\begin{aligned}
& \text { } K=K a_1 \times K a_2=4.5 \times 10^{-3} \times 1.7 \times 10^{-10} \\
& =7.65 \times 10^{-13} \\
& {\left[\mathrm{H}^{+}\right]=\sqrt{K C}=\sqrt{7.65 \times 10^{-13} \times 0.01}} \\
& =\sqrt{7.65 \times 10^{-15}}=0.87 \times 10^{-7} \\
& \mathrm{pH}=-\log 0.87 \times 10^{-7}=7-0.93=6.07 \\
&
\end{aligned}
$$
\begin{aligned}
& \text { } K=K a_1 \times K a_2=4.5 \times 10^{-3} \times 1.7 \times 10^{-10} \\
& =7.65 \times 10^{-13} \\
& {\left[\mathrm{H}^{+}\right]=\sqrt{K C}=\sqrt{7.65 \times 10^{-13} \times 0.01}} \\
& =\sqrt{7.65 \times 10^{-15}}=0.87 \times 10^{-7} \\
& \mathrm{pH}=-\log 0.87 \times 10^{-7}=7-0.93=6.07 \\
&
\end{aligned}
$$
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