## Chemistry: The Molecular Science (5th Edition)

$pH = 1.18$
1000ml = 1L 50ml = 0.05 L 10ml = 0.01 L 1. Find the numbers of moles: $C(HCl) * V(HCl) = 0.1* 0.05 = 5 \times 10^{-3}$ moles $C(NaOH) * V(NaOH) = 0.1* 0.01 = 1 \times 10^{-3}$ moles 2. Write the acid-base reaction: $HCl(aq) + NaOH(aq) -- \gt NaCl(aq) + H_2O(l)$ - Total volume: 0.05 + 0.01 = 0.06L 3. Since the base is the limiting reactant, only $0.001$ mol of the compounds will react. Therefore: Concentration (M) = $\frac{n(mol)}{Volume(L)}$ $[HCl] = 0.005 - 0.001 = 4 \times 10^{-3}$ moles. Concentration: $\frac{4 \times 10^{-3}}{ 0.06} = 0.067M$ $[NaOH] = 0.001 - 0.001 = 0$ moles - Since $HCl$ is a strong acid: $[HCl] = [H_3O^+] = 0.067M$ 5. Calculate the pH Value $pH = -log[H_3O^+]$ $pH = -log( 0.067)$ $pH = 1.18$