AS LEVEL Physical chemistry - Energy changes in chemistry

Flashcards about energy changes in chemistry.

Enthalpy (or heat content)

The total chemical energy of a substance.

Enthalpy change (ΔH)

Change in chemical energy during a chemical reaction.

ΔH = ΔU + PΔV

The relationship between enthalpy change (ΔH) and internal energy change (ΔU) at constant pressure (P) and volume change (ΔV).

Exothermic Reaction

A reaction that releases heat, resulting in a negative enthalpy change (ΔH < 0).

Endothermic Reaction

A reaction that absorbs heat, resulting in a positive enthalpy change (ΔH > 0).

Specific Heat Capacity (c)

The amount of energy needed to raise the temperature of a substance by one degree Celsius (or Kelvin); for water, c = 4.18 J g⁻¹ K⁻¹.

q = mcΔT

Equation to calculate heat transfer (q), where m is mass, c is specific heat capacity, and ΔT is the temperature change.

ΔH = -mcΔT

Equation to calculate the enthalpy change (ΔH) of a reaction based on heat transfer (q).

Calorimeter

An apparatus used for measuring heat changes in a reaction or process.

Enthalpy change of solution (ΔHsol)

The enthalpy change when one mole of a substance is dissolved in water.

Enthalpy change of neutralization (ΔHneut)

The enthalpy change accompanying the neutralization of an acid by a base to give one mole of water.

Law of Conservation of Energy

Energy cannot be created or destroyed; it can only be converted into another form of energy.

Standard Conditions

298K and 101 kPa