(Solved): #26 A buffer solution contains 0.86mol of phenol (HC6H5O) and 0.88mol of sodium phenoxide ...

A buffer solution contains $0.86\mathrm{mol}$ of phenol $\left({\mathrm{HC}}_6{\mathrm{H}}_5\mathrm{O}\right)$ and $0.88\mathrm{mol}$ of sodium phenoxide $\left({\mathrm{NaC}}_6{\mathrm{H}}_5\mathrm{O}\right)$ in $6.40\mathrm{L}$. The ${\mathrm{K}}_{\mathrm{a}}$ of phenol $\left({\mathrm{HC}}_6{\mathrm{H}}_5\mathrm{O}\right)$ is ${\mathrm{K}}_{\mathrm{a}}=1.3\mathrm{e}-10$. (a) What is the $\mathrm{pH}$ of this buffer? $\mathrm{pH}=$ (b) What is the $\mathrm{pH}$ of the buffer after the addition of $0.45\mathrm{mol}$ of $\mathrm{NaOH}$ ? (assume no volume change) $\mathrm{pH}=$ (c) What is the $\mathrm{pH}$ of the original buffer after the addition of $0.26\mathrm{mol}$ of $\mathrm{HI}$ ? (assume no volume change) $\mathrm{pH}=$