Thermodynamics

Question 1

Metals and non metals form:

Answer 1

Ionic compounds

Question 2

Definition of lattice enthalpy of formation:

Answer 2

The enthalpy change when one mole of crystalline/solid ionic substance is formed from its constituent ions in their gaseous state under standard conditions.

Question 3

Definition of lattice dissociation enthalpy:

Answer 3

The enthalpy change when one mole of crystalline/solid ionic substance breaks into its smaller constituent ions in their gaseous state under standard conditions.

Question 4

Definition of first ionisation energy:

Answer 4

The enthalpy change when one mole of gaseous atoms loses one electron per atom under standard conditions.

Question 5

Definition of second ionisation energy:

Answer 5

The enthalpy change when one mole of gaseous +1 ions lose one electron per atom under standard conditions

Question 6

Definition of first electron affinity enthalpy:

Answer 6

The enthalpy change when one mole of gaseous atoms gains one electron per atom under standard conditions.

Question 7

Definition of second electron affinity enthalpy:

Answer 7

The enthalpy change when one mole of gaseous -1 ions gain an electron per atom under standard conditions.

Question 8

Definition of hydration enthalpy:

Answer 8

The enthalpy change when one mole of gaseous ions become hydrated or aqueous.

Question 9

Definition of enthalpy of solution:

Answer 9

The enthalpy change when one mole of an ionic solid dissolved into enough water to completely separate all the ions.

Question 10

Definition of enthalpy of formation:

Answer 10

The enthalpy change when one mole of a substance is formed from its constituent elements in their standard states under standard conditions.

Question 11

Definition of enthalpy of combustion:

Answer 11

The enthalpy change when one mole of a substance is completely combusted in oxygen in their standard states under standard conditions.

Question 12

Definition of enthalpy of atomisation of an element:

Answer 12

The enthalpy change when one mole of gaseous atoms are produced from one mole of standard state elements.

Question 13

Definition of enthalpy of bond dissociation:

Answer 13

Enthalpy change when one mole of a covalent bond is broken in the gaseous state.

Question 14

What is entropy?

Answer 14

The measure of dissociation.

Question 15

What is entropy measured in?

Answer 15

JK^1mol^1 has the symbol S

Question 16

🔺S total =

Answer 16

🔺S reaction - 🔺S surroundings

Question 17

🔺S reaction =

Answer 17

🔺S products - 🔺S reactants

Question 18

Definition of enthalpy change of atomisation in a compound:

Answer 18

The enthalpy change when 1 mole of a compound in its standard state is converted to its gaseous atoms.

Question 19

Exothermic thermic reactions have a … value

Answer 19

Exothermic reactions have a negative value, because heat energy is given out.

Question 20

Endothermic reactions have a … value

Answer 20

Endothermic reactions have a positive value, because heat energy is absorbed.

Question 21

In order for a reaction to be feasible 🔺G must be:

Answer 21

Must be negative or zero.

Question 22

Equation to calculate 🔺G:

Answer 22

🔺G = 🔺H - T🔺S

Question 23

How does feasibility depend on temperature?

Answer 23

If H is positive and S is positive than the reaction would be feasible at some temperatures but will be at a high enough temperature.

If H is negative and S is negative then the reaction will be feasible at lower temperatures but not visible at higher temperatures.

If H is positive and S is positive and G is negative the reaction will be feasible at any temperature

If H is positive and S is negative than G is positive the reaction ISN’T feasible.