Two Experimental Runs Are Performed to Determine the Calorimetric Properties

Multiple Choice

Two experimental runs are performed to determine the calorimetric properties of an alcohol that has a melting point of -10°C. In the first run, a 200-g cube of frozen alcohol, at the melting point, is added to 300 g of water at 20°C in a styrofoam container. When thermal equilibrium is reached, the alcohol-water solution is at a temperature of 5.0°C. In the second run, an identical cube of alcohol is added to 500 g of water at 20°C and the temperature at thermal equilibrium is 10°C. The specific heat of water is 4190 J/kg·K. Assume that no heat is exchanged with the styrofoam container and with the surroundings. The heat of fusion of the alcohol is closest to

A) 5.5 × 10⁴ J/kg
B) 6.3 × 10⁴ J/kg
C) 7.1 × 10⁴ J/kg
D) 7.9 × 10⁴ J/kg
E) 8.7 × 10⁴ J/kg