Enthalpy

Question 1

What is the definition of enthalpy

Answer 1

Energy change per mole

Question 2

How can enthalpy be measured

Answer 2

Using bond energies data
Experimental data
Hess’ Law

Question 3

How do you calculate enthalpy from experimental data

Answer 3

using -MCAT/no. moles

Question 4

What processes give endothermic data in a Born-Haber Cycle

Answer 4

Enthalpy atomisation

Enthalpy Ionisation

Question 5

What processes give exothermic data in a Born-Haber cycle

Answer 5

Enthalpy of Lattice

Enthalpy of electron affinity

Question 6

How do you calculate the enthalpy of solution

Answer 6

HLatt - H Hydration data

Question 7

What does the enthalpy of solution tell you

Answer 7

If negative then it is soluble, if positive then insoluble

Question 8

Describe polarisation of group 1,2 and 3 chlorides

Answer 8

1 - NaCl, not polarised as the cation charge isn’t strong enough
2 - MgCl2, polarised, electron density pulled towards the cation
3 - MgCl3, Entirely polarised, no longer ionic, now covalent