Use a heating curve to relate the addition of energy over the course of time to temperature changes and phase changes.
Ammonia (NH3) has a heat of vaporization of 23.4 kJ/mol. What quantity of energy (in kilojoules) is required to change 76.1 grams of ammonia from the liquid to the gaseous state?
Quantity of Energy
kJ
Liquid bromine (Br2) has a heat of vaporization of 15.438 kJ/mol. What quantity of energy (in kilojoules) is required to vaporize 49.5 g of liquid bromine?
Consider the heating curve for water as shown. A 40.7-gram sample of water at 23.0°C is warmed to its boiling point and then boiled. Given that the specific heat capacity of liquid water is 4.184 J/g/°C and the heat of vaporization of water at its boiling point (100.0°C) is 40.8 kJ/mol, determine …
… the quantity of energy (in kilojoules) required to warm the liquid water from 23.0°C to its boiling point (100°C).
… the quantity of energy (in kilojoules) required to vaporize the liquid water.
… the total quantity of energy (in kilojoules) required to change 40.7 grams of liquid water at 23.0°C to the gaseous state at 100.0°C.
Total Energy
Consider the heating curve for water as shown. A 32.3-gram sample of frozen water at -14.4°C is warmed to its melting point and then melted. It is then warmed to a temperature of 27.4°C. Given:
Specific heat capacity of ice is 2.108 J/g/°C
Specific heat capacity of liquid water is 4.184 J/g/°C
Heat of fusion of water is 6.01 kJ/mol.
Determine …
… the quantity of energy (in kilojoules) required to warm the ice from -14.4°C to its melting point (0.0°C).
… the quantity of energy (in kilojoules) required to melt the ice.
… the quantity of energy (in kilojoules) required to warm the liquid water from 0.0°C to 27.4°C.
… the total quantity of energy (in kilojoules) required to change 32.3 grams of solid water at -14.4°C to the liquid water at 27.4°C.
Suppose a 50.2-gram sample of water at -14.3°C is warmed, melted, warmed, boiled, and warmed to a final temperature of 139.5°C. Given that …
Specific heat capacity of water vapor is 1.996 J/g/°C
Heat of vaporization of water is 40.8 kJ/mol.
… the quantity of energy (in kilojoules) required to warm the water from -14.3°C to its melting point (0.0°C).
… the quantity of energy (in kilojoules) required to melt the water.
… the quantity of energy (in kilojoules) required to warm the liquid water from 0.0°C to 100.0°C.
… the quantity of energy (in kilojoules) required to warm the water vapor to 139.5°C
… the total quantity of energy (in kilojoules) required to change the water from -14.3°C to 139.5°C.