Chemistry 2000, Fall 96, Assignment 3

Due: November 7

All questions are equally weighted. Relevant data will be found in the textbook.

1. What is the pH of a solution made by mixing 100mL of 0.13mol/L hydrofluoric acid with 50mL of 0.51mol/L sodium hydroxide solution at ?
2. What is the solubility of barium carbonate in water? Express your answer in g/L.
3. A 300kg aluminium car engine has an operating temperature of . On a morning where the air temperature is , how much heat does it take to bring the engine up to its operating temperature?
4. A kettle contains 1kg of water. The water starts at . If 450kJ of heat is supplied to the kettle, what mass of water is left in the kettle when the heat is turned off? (450kJ is the amount of heat generated by a 1500W kettle in 5min.)
5. What is the solubility of lead (II) sulfide in a pH 12 buffer? Report your answer in mol/L.

   Hint: There are a pair of coupled equilibria in this problem. The pH can be used to determine the majority sulfide species at equilibrium. Furthermore, it is possible to obtain an equilibrium constant for the overall process and the problem is probably easier to solve that way.