3. Pure water is carbonated by means of bubbling gaseous CO2 through it. Then it is bottled. a. If the air space in the bottle above the water contains only CO2 at a pressure of 2 atm, what is the equilibrium pH of the carbonated water? Use an exact solution. (assume T = 25ºC) (3 marks) b. Solve part a) using simplifying assumptions. Check the assumptions. (3 marks) c. The bottle is opened, and the water is poured into a glass. Assume that the surrounding atmosphere is unpolluted at T = 25ºC. What is the new equilibrium pH? (Hint: You should not need to do any new calculations for this, but justify your answer). In terms of the concentration of dissolved CO2 species (H2CO3 * , HCO3 - , CO3 2- ) describe the changes that take place as the new equilibrium is approached (increase or decrease) (3 marks) d. Carry out this experiment: Pour a carbonated beverage (water, coke, 7-UP, beer etc.) into a glass and then sprinkle some salt into the beverage. Describe and explain what you have observed. Does the addition of a small amount of salt influence the equilibrium pH? Does it influence the rate of approach to equilibrium? What is the role of the salt?
3. Pure water is carbonated by means of bubbling gaseous CO2 through it. Then it is bottled. a. If the air space in the bottle above the water contains only CO2 at a pressure of 2 atm, what is the equilibrium pH of the carbonated water? Use an exact solution. (assume T = 25ºC) (3 marks) b. Solve part a) using simplifying assumptions. Check the assumptions. (3 marks) c. The bottle is opened, and the water is poured into a glass. Assume that the surrounding atmosphere is unpolluted at T = 25ºC. What is the new equilibrium pH? (Hint: You should not need to do any new calculations for this, but justify your answer). In terms of the concentration of dissolved CO2 species (H2CO3 * , HCO3 - , CO3 2- ) describe the changes that take place as the new equilibrium is approached (increase or decrease) (3 marks) d. Carry out this experiment: Pour a carbonated beverage (water, coke, 7-UP, beer etc.) into a glass and then sprinkle some salt into the beverage. Describe and explain what you have observed. Does the addition of a small amount of salt influence the equilibrium pH? Does it influence the rate of approach to equilibrium? What is the role of the salt?
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