Energetics

Question 1

Standard enthalpy change of reaction

Answer 1

The enthalpy change when molar quantities of reactants stated in the chemical equation react to form products under Standard condition.

Question 2

Standard Condition

Answer 2

298K, 1 bar Pressure, solutions at 1moldm-3

Question 3

Bond energy

Answer 3

The enthalpy change to break 1 mole of covalent bond between 2 gaseous atom.

Question 4

Calculation of Standard enthalpy change of reaction

Answer 4

1) BE(Rxt) - BE(Pdt)
2) Hc(Rxt) - Hc(Pdt)
3) Hf(Pdt) - Hf(Rxt)

Question 5

Standard Enthalpy change of Atomisation for elements

Answer 5

Enthalpy change in forming 1 mole of gaseous atom from its element in their standard state at standard condition

Question 6

Standard Enthalpy change of Atomisation of compound

Answer 6

The enthalpy change in forming gaseous atoms from 1 mole of substance at standard condition.

Question 7

Standard enthalpy change of Combustion

Answer 7

The enthalpy change to completely burn 1 mole of substance in excess oxygen at standard condition

Question 8

Standard enthalpy change of Formation

Answer 8

Enthalpy change in forming 1 mole of compound from their constituent elements in their standard state at standard condition.

Question 9

Standard enthalpy change of Neutralisation

Answer 9

The enthalpy change when an acid react with base to form 1 mole of water in dilute aqueous solution at standard condition.

Question 10

Hess’ Law

Answer 10

The enthalpy change of a reaction is the same regardless of path taken, given initial state of reactant and final state of product are the same

Question 11

Lattice Energy

Answer 11

The enthalpy change to form 1 mole of solid ionic compound from its constituent gaseous ions.

Question 12

First Ionisation Energy

Answer 12

Energy required to remove 1 mole of electrons from 1 mole of gaseous atom to form 1 mole of singly charged gaseous cations.

Question 13

First Electron Affinity

Answer 13

The enthalpy change when 1 mole of electrons is gained by 1 mole of gaseous atoms to form 1 mole of singly charged gaseous anions.

Question 14

Standard enthalpy change of Hydration

Answer 14

The enthalpy change when 1 mole of the gaseous ions dissolve in a large amount of water to form 1 mole of aqueous ion under Standard Condition

Question 15

Standard Enthalpy change of Solution

Answer 15

The enthalpy change when 1 mole of substance is completely dissolved in a large excess of solvent to form an infinitely dilute solution at Standard condition.

Question 16

Equation for H(soln)

Answer 16

H(soln) = H(Hyd)-LE

Question 17

Entropy

Answer 17

A quantity which measure degree of disorder of a system

Question 18

Factors affecting Entropy

Answer 18

1) Change in Temp
2) Change in States
3) Change in number of particles
4) Mixing of Particles (Gas and Solid)

Question 19

Standard Gibbs free energy change of reaction

Answer 19

The maximum amount of energy that is available to do work under Standard Condition
Units= kJ mol-1

Question 20

Equation of G

Answer 20

Change in G = Change in Enthalpy energy - T(Change in Entropy)