At 40°C, the density of heavy water is 1.02 g/ml and its ionic product is . Which of the following i — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

(a) Molar mass of $\text{D}_2\text{O}$ is $20\text{ g/mol}$. Molarity = $1020\text{ g/L} / 20\text{ g/mol} = 51\text{ M}$ (Correct). (b) $K_d = K_w / [\text{D}_2\text{O}] = 5.1 \times 10^{-15} / 51 = 1.0 \times 10^{-16}$ (Correct). (c) $[\text{D}^+] = \sqrt{K_w} = \sqrt{5.1 \times 10^{-15}} \approx 7.14 \times 10^{-8}\text{ M}$. Degree of dissociation $\alpha = [\text{D}^+] / C = 7.14 \times 10^{-8} / 51 \approx 1.4 \times 10^{-9}$, not $10^{-8}$. (Incorrect). (d) Molality = $(1000\text{ g} / 20\text{ g/mol}) / 1\text{ kg} = 50\text{ m}$ (Correct).