(Solved): Sodium benzoate (NaC6H5COO) is a food preservative. What is the concentration of the conjugat ...

Sodium benzoate $\left({\mathrm{NaC}}_6{\mathrm{H}}_5\mathrm{COO}\right)$ is a food preservative. What is the concentration of the conjugate acid (benzoic acid) in a $0.271\mathrm{M}$ solution of sodium benzoate? The Ka of benzoic acid $6.5\times 10^{?5}$, (Enter in scientific notation $(X.X{X}^{?}10^{?}Y$ ) with two digits after the decimal point) Compounds other than water can undergo auto-ionization. Imagine a compound, ${\mathrm{H}}_2\mathrm{X}$, which reacts according to the reaction below. What is the $\mathrm{pH}$ of pure solution of ${\mathrm{H}}_2\mathrm{X}$ where the ${\mathrm{K}}_{\mathrm{w}}$ is 0.000083 ? ${\mathrm{H}}_2\mathrm{X}+{\mathrm{H}}_2\mathrm{X}?{\mathrm{H}}_3{\mathrm{X}}^{+}+\mathrm{HX}$ (Enter in standard notation with two digits after the decimal point)