Equilibria: describe question

A student is studying buffer solutions and solubility equilibria.

(a) Describe how a buffer solution can be prepared using ethanoic acid and sodium ethanoate. Include an equation to show how this buffer resists a change in pH when a small amount of aqueous sodium hydroxide is added.

(b) The hydrogencarbonate ion, $\ce{HCO3-}$, is part of the buffer system that controls the pH of human blood.

Describe the role of $\ce{HCO3-}$ in this buffer system. Identify the conjugate acid–base pair involved.

(c) Describe the meaning of the term solubility product, $K_{\mathrm{sp}}$, and write an expression for $K_{\mathrm{sp}}$ for calcium phosphate, $\ce{Ca3(PO4)2}$.