79G sample of water at 21 Celsius is heated until it becomes steam with the temperature of 143 Celsius. Find the change in the heat content of the system.

1 answer

To find the change in the heat content of the system, we need to calculate the amount of heat added to the water to heat it up from 21°C to 100°C (boiling point) and then from 100°C to 143°C.

First, we calculate the heat required to raise the temperature of the water from 21°C to 100°C.

Q = m * Cp * ΔT
where:
Q = heat added (Joules)
m = mass of water (79g)
Cp = specific heat capacity of water (4.18 J/g°C)
ΔT = change in temperature (100°C - 21°C)

Q1 = 79g * 4.18 J/g°C * (100°C - 21°C)
Q1 = 6,448.38 J

Next, we calculate the heat required to raise the temperature of the water from 100°C to 143°C.

Q2 = m * Cp * ΔT
where:
Q2 = heat added (Joules)
m = mass of water in steam form (79g, since we are assuming no water is lost as steam)
Cp = specific heat capacity of steam (2.03 J/g°C)
ΔT = change in temperature (143°C - 100°C)

Q2 = 79g * 2.03 J/g°C * (143°C - 100°C)
Q2 = 3,396.11 J

Therefore, the total change in heat content of the system is the sum of Q1 and Q2:

ΔQ = Q1 + Q2
ΔQ = 6,448.38 J + 3,396.11 J
ΔQ = 9,844.49 J

Therefore, the change in the heat content of the system is 9,844.49 Joules.