According to its label, each tablet of Alka-Seltzer contains 1.916 g (0.0228 mol) of sodium hydrogen carbonate. Consider and Alka-Seltzer tablet dissolved in 150 mL of water: (a) What equilibrium determines the pH? (b) What is the pH of the solution?

(a) The equilibrium that determines the pH of the solution is the dissociation of water: H2O ? H+ + OH-. This equilibrium determines the concentration of H+ in solution, which in turn determines the pH. (b) To find the pH, we need to calculate the concentration of H+ in solution. Since the tablets contain sodium hydrogen carbonate, we can write the following equation for its dissolution in water: NaHCO3 + H2O ? Na+ + HCO3- + H+ The H+ ions produced in this reaction are what determine the pH. We can use the balanced equation to calculate the moles of H+ produced for each tablet: 1 tablet Alka-Seltzer = 0.0228 mol NaHCO3 1 mol NaHCO3 produces 1 mol H+ Therefore, 1 tablet Alka-Seltzer produces 0.0228 mol H+ Next, we need to find the concentration of H+ in the solution. We know that the tablet is dissolved in 150 mL of water, which is equivalent to 0.150 L. Since we have 0.0228 mol of H+ in solution, we can use the following formula to calculate the concentration: [H+] = moles of H+ / volume of solution [H+] = 0.0228 mol / 0.150 L [H+] = 0.152 M Finally, we can use the concentration of H+ to calculate the pH using the formula: pH = -log[H+] pH = -log(0.152) pH = 0.818 Therefore, the pH of the solution is \approx imately 0.818.