Thermochemistry Review

Front

What type of reaction is characterized by the release of heat?

Back

Exothermic reaction.

Front

If ΔH is positive, where is heat shown in the thermochemical equation?

Back

On the reactant side.

Front

What is the specific heat of a substance if a 24.0 gram sample of copper absorbs 4378J of heat when heated from 25.0°C to 500.0°C?

Back

0.384 J/g°C.

Front

What does a negative ΔH indicate about a reaction?

Back

The reaction is exothermic.

Front

How do you calculate the enthalpy change (ΔH) for a reaction?

Back

ΔH = ΣΔHf(products) - ΣΔHf(reactants).

Front

What is the enthalpy change for the reaction Ca(OH)2 -> CaO + H2O given the ΔHf values?

Back

62.8 kJ.

Front

Define an endothermic reaction.

Back

A reaction that absorbs heat from the surroundings.

Front

What is the significance of the enthalpy of formation (ΔHf)?

Back

It is the heat change when one mole of a compound is formed from its elements in their standard states.

Front

What is the specific heat formula?

Back

q = m × c × ΔT, where q is heat, m is mass, c is specific heat, and ΔT is the change in temperature.

Front

What happens to the temperature of a substance during an endothermic reaction?

Back

The temperature decreases as heat is absorbed.