2 7.2.4 Quiz: Melting and Boiling Question 7 of 10
What is a vapor?
O A. A substance that is always in the solid or liquid phase at room
temperature
B. A substance that forms a gas, but only at very high temperatures
C. A substance that is in the gas phase at a temperature at which it
would normally be a solid or liquid
O D. A substance that has a much higher melting point and boiling
point than other similar substances
SUBMIT

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.