Question

1a. The following information is given for cobalt at 1 atm:

Tb = 3097.00°C		deltaHvap(3097.00°C) =  J/g
Tm = 1495.00°C		deltaHfus(1495.00°C) =  J/g
Specific heat solid = 0.4180 J/g °C
Specific heat liquid = 0.6860 J/g °C

A 40.00 g sample of solid cobalt is initially at 1468.00°C. If the sample is heated at constant pressure (P = 1 atm), _____ kJ of heat are needed to raise the temperature of the sample to 1686.00°C.

1b: The following information is given for mercury at 1 atm:

Tb = 356.60°C		deltaHvap(356.60°C) =  J/g
Tm = –38.90°C		deltaHfus(–38.90°C) =  J/g
Specific heat gas = 0.1040 J/g °C
Specific heat liquid = 0.1390 J/g °C

A 20.70 g sample of liquid mercury is initially at 246.30°C. If the sample is heated at constant pressure (P = 1 atm), ______ kJ of energy are needed to raise the temperature of the sample to 386.50°C.

Answer 1

1 (a)

Heat required to raise the temperature of the sample of cobalt from 1468.00 0C to 1686.00°C (H) =

Mass of the sample * Specific heat of solid cobalt * Temperature change

= 40.00 g * 0.4180 J/g °C * (1686.00 - 1468.00) 0C

= 3645 J

= 3.645 kJ

(b)

Heat required to raise the temperature of the sample of mercury from 246.30°C to 386.50°C (H) =

Mass of the sample * Specific heat of liquid mercury * Temperature change

= 20.70 g * 0.1390 J/g °C * (386.50 - 246.30) 0C

= 403.4 J

= 0.4034 kJ