AP Chemistry - Thermochemistry Big review

Front

What is thermochemistry?

Back

Thermochemistry is the branch of chemistry that deals with the relationship between chemical reactions and heat energy.

Front

Define endothermic reaction.

Back

An endothermic reaction is a chemical reaction that absorbs heat from its surroundings.

Front

Define exothermic reaction.

Back

An exothermic reaction is a chemical reaction that releases heat to its surroundings.

Front

What is the significance of the enthalpy change (ΔH) in a reaction?

Back

The enthalpy change (ΔH) indicates whether a reaction is endothermic (ΔH > 0) or exothermic (ΔH < 0).

Front

How do you calculate the energy required to melt a substance?

Back

Energy required = mass (g) × heat of fusion (kJ/mol) / molar mass (g/mol).

Front

What is heat of fusion?

Back

Heat of fusion is the amount of energy required to change a substance from solid to liquid at its melting point.

Front

What happens to temperature during an endothermic reaction?

Back

The temperature of the surroundings decreases as the system absorbs heat.

Front

What happens to temperature during an exothermic reaction?

Back

The temperature of the surroundings increases as the system releases heat.

Front

What is the molar mass of methane (CH₄)?

Back

The molar mass of methane (CH₄) is 16 g/mol.

Front

In a chemical equation, where is the heat term placed for an endothermic reaction?

Back

The heat term is placed on the reactant side and is written as a positive number.