Enthalpy

Question 1

The change in enthalpy at constant pressure equals the heat lost or gained at constant pressure

Answer 1

True

Question 2

DeltaE is easier to measure and more useful than DeltaH.

Answer 2

False. Delta H is more useful because more physical and chemical reactions happen at constant pressure and it is more easily measured.

Question 3

When deltaH is positive…

Answer 3

The reaction in endothermic (heat is flowing in)

Question 4

When deltaH is negative…

Answer 4

The reaction is exothermic (heat is flowing out)

Question 5

What is the enthalpy of a reaction?

Answer 5

It refers to the amount of heat given off by a reaction.

Question 6

Enthalpy is considered to be what type of property?

Answer 6

Extensive, because it depends on the amount of reactant consumed in the process.

Question 7

The enthalpy change for a reaction is equal in magnitude and opposite in sign to deltaH for the reverse reaction

Answer 7

CH4 + 2O2 -> CO2 + H2O
Delta H = -890kJ

CO2 + 2H20 -> CH4 + 2O2
Delta H = 890kJ

Question 8

Enthalpy depends on what?

Answer 8

The physical state of the material and the temperature.

Question 9

The heat given off by a reaction is…

Answer 9

The same magnitude as the heat absorbed by the solution, so the temperature increases