Summary Notes: Module 5: Physical Chemistry & Transition Elements: Chemistry OCR A A Level

Vertical Section

pH increases rapidly on the addition of a small volume of base. acid/base concentration is similar.

Continuous Monitoring

Continuous measurements taken during the course of a reaction.

Initial Rate

Instantaneous rate at the start of a reaction when time=0, found by measuring.

Clock Reaction

A convenient way of obtaining initial rate with single measurement.

pH Meter

Electrode (dipped into solution), connected to meter displaying reading.

Equivalence Point

The volume of one solution that exactly reacts with the volume of the other solution (at the centre of the vertical section).

Acid-base Indicator

Weak acid with distinctively different colour to conjugate base (e.g. methyl orange: weak acid is red, conjugate base is yellow, end point colour between two so orange).

Lattice Enthalpy

The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions (always exothermic).

Entropy

Dispersal of energy within the chemicals making up the chemical system (units J•K^-1•mol^-1).

Standard Entropy

The entropy of one mole of a substance under standard conditions (+ve).

Feasibility/spontaneity

Whether a reaction is able to happen and is energetically feasible.

Free energy change ΔG

Overall energy change during a chemical reaction. Made up of enthalpy change and entropy change.

Voltaic Cell

Converts chemical energy into electrical energy. Made by connecting 2 different half cells, allowing electrons to flow (not made by mixing cells- would produce heat energy.

Half Cell

Contains the species present in a redox half equation.

Metal/Metal Ion

Phase boundary where metal in contact with its ions, equilibrium is set up.

Ion/Ion half cell

Ions of same element in different oxidation states. Inert metal electrode (Pt) used.

Metallic

High melting/boiling point, shiny, conduct electricity/heat.