8. Thermodynamics Flashcards Preview

AQA A Level Physical Chemistry > 8. Thermodynamics > Flashcards

Flashcards in 8. Thermodynamics Deck (114)
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1

What is enthalpy change?

The heat energy transferred in a reaction at constant pressure

2

Symbol for enthalpy change?

ΔH

3

What is standard enthalpy change?

The heat energy transferred in a reaction at 100kPa and 298K

4

What does the sign on an enthalpy change value depend on?

Whether the reaction is exothermic or endothermic

5

What does a negative enthalpy change value indicate?

The reaction is exothermic

6

What does a positive enthalpy change value indicate?

The reaction is endothermic

7

What is standard enthalpy change of formation?

Enthalpy change when 1 mole of substance is formed from its constituent elements with all reactants and products in standard states under standard conditions

8

What is standard enthalpy change of combustion?

Enthalpy change when 1 mole of a substance is completely burned in oxygen with all reactants and products in standard states under standard conditions

9

How is enthalpy change calculated in terms of the sum of bonds broken and formed?

sum of bonds broken - sum of bonds formed

10

What is the equation for enthalpy of formation of sodium oxide?

2Na (s) + 1/2 O₂ (g) → Na₂O (s)

11

What is the ΔH sign for enthalpy of formation?

Positive or negative

12

What is the ΔH sign for enthalpy of combustion?

Negative

13

What is the equation for the enthalpy of combustion of hydrogen?

H₂ (g) + 1/2 O₂ (g) → H₂O (l)

14

What is ionisation enthalpy also known as?

First/second etc. ionisation energy

15

What is first ionisation energy?

Enthalpy change when each atom in one mole of gaseous atoms loses one electron to form one mole of gaseous 1+ ions

16

What is second ionisation energy?

Enthalpy change when each ion in one mole of gaseous 1+ ions loses one electron to form one mole of gaseous 2+ ions

17

What is first electron affinity?

Enthalpy change when each atom in one mole of gaseous atoms gains one electron to form one mole of gaseous 1- ions

18

What is second electron affinity?

Enthalpy change when each ion in one mole of gaseous 1- gains one electron to form one mole of gaseous 2- ions

19

What is the ΔH sign for ionisation enthalpy?

Positive

20

What is the ΔH sign for first electron affinity?

Negative

21

What is the ΔH sign for second electron affinity?

Positive

22

What is the equation for enthalpy of first ionisation energy of magnesium?

Mg (g) → Mg⁺ (g) + e⁻

23

What is the equation for enthalpy of second ionisation energy of magnesium?

Mg⁺ (g) → Mg²⁺ (g) + e⁻

24

What is the equation for first electron affinity of oxygen?

O (g) + e⁻ → O⁻(g)

25

What is the equation for second electron affinity of oxygen?

O⁻ (g) + e⁻ → O²⁻ (g)

26

What is bond dissociation?

Enthalpy change when one mole of covalent bonds is broken in the gaseous state

27

What is enthalpy of atomisation of an element?

Enthalpy change when one mole of gaseous atoms is produced from an element in its standard state

28

What is enthalpy of atomisation of a compound?

Enthalpy change when gaseous atoms are produced from one mole of a compound in its standard state

29

What is lattice enthalpy of formation?

Enthalpy change when one mole of a solid ionic compound is formed from into its constituent ions in the gas phase

30

What is lattice enthalpy of dissociation?

Enthalpy change when one mole of a solid ionic compound is broken up into its constituent ions in the gas phase