Question

1. A 48.0−g sample of an unknown metal at 99°C was placed in a constant-pressure calorimeter containing 70.0 g of water at 24.0°C. The final temperature of the system was found to be 28.4°C. Calculate the specific heat of the metal. (The heat capacity of the calorimeter is 10.4 J/°C.)

2.A balloon 19.0 m in diameter is inflated with helium at 23°C. Calculate the work done (in kJ) during the inflation process if the atmospheric pressure is 97.7 kPa.

3.Ice at 0.0°C is placed in a Styrofoam cup containing 360 g of a soft drink at 25.8°C. The specific heat of the drink is about the same as that of water. Some ice remains after the ice and soft drink reach an equilibrium temperature of 0.0°C. Determine the mass of ice that has melted. Ignore the heat capacity of the cup. (Hint: It takes 334 J to melt 1 g of ice at 0.0°C.)

4. When 1.049 g of naphthalene (C10H8) is burned in a constant-volume bomb calorimeter at 298 K, 42.16 kJ of heat is evolved.

Calculate ΔU and w for the reaction on a molar basis.