2. Thermodynamics Definitions Flashcards

A2 thermodynamics definitions

1
Q

Define Enthalpy of Formation

A

Enthalpy change when 1 mole of a substance is formed from its constituent elements with all substances in their standard states.

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2
Q

Is Enthalpy of Formation endo or exothermic?

A

exothermic (-ive) for most substances

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3
Q

Define Enthalpy of Combustion

A

Enthalpy change when 1 mole of a substance undergoes complete combustion in oxygen with all substances in their standard states

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4
Q

Is Enthalpy of Combustion endo or exothermic?

A

Exothermic (-ive)

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5
Q

Define Enthalpy of Neutralisation

A

Enthalpy change when 1 mole of water is formed in a reaction between an acid and alkali under standard conditions

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6
Q

Is enthalpy of neutralisation endo or exothermic?

A

Exothermic (-ive)

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7
Q

Define first ionisation energy

A

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

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8
Q

Is ionisation energy endo or exothermic?

A

Endothermic (+ive)

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9
Q

First ionisation energy of Mg?

A

Mg(g) –> Mg+(g) + e-

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10
Q

Define second ionisation energy

A

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

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11
Q

Second ionisation energy of Mg?

A

Mg+(g) —> Mg2+(g) + e-

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12
Q

Define first electron affinity

A

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

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13
Q

Is first electron affinity endo or exothermic?

A

Exothermic (-ive) for many non-metals

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14
Q

First electron affinity of O2?

A

O(g) + e- —> O-(g)

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15
Q

Define second electron affinity

A

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

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16
Q

Is second electron affinity endo or exothermic?

A

Endothermic (+ive) as adding -ive electron to -ive ion

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17
Q

Second electron affinity of O2?

A

O-(g) + e- —> O^2-

18
Q

Define enthalpy of atomisation

A

Enthalpy change when 1 mole of gaseous atoms is produced from an element in its standard state

19
Q

Is enthalpy of atomisation endo or exothermic?

A

Endothermic (+ive)

20
Q

Enthalpy of atomisation of iodine?

A

1/2 I2(s) —-> I(g)

21
Q

Define hydration enthalpy

A

Enthalpy change when 1 mole of gaseous ions become hydrated (dissolved in water)

22
Q

Is hydration enthalpy endo or exothermic?

A

Exothermic (-ive)

23
Q

Hydration enthalpy of Mg ions?

A

Mg^2+(g) + aq —> Mg^2+(aq)

24
Q

Define enthalpy of solution

A

Enthalpy change when 1 mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are well separated and do not interact with each other

25
Q

Is enthalpy of solution endo or exothermic?

A

Varies`

26
Q

Enthalpy of solution of Magnesium Chloride?

A

MgCl2(s) + aq —-> Mg^2+(aq) + 2Cl^(aq)

27
Q

Define bond dissociation enthalpy

A

Enthalpy change when 1 mole of covalent bonds is broken in the gaseous state

28
Q

Is bond dissociation enthalpy endo or exothermic?

A

Endothermic (+ive)

29
Q

Bond dissociation enthalpy of I-I bond?

A

I2(g) —> 2I(g)

30
Q

Define lattice enthalpy of formation

A

Enthalpy change when 1 mole of a solid ionic compound is formed from its constituent ions in the gas phase

31
Q

Is lattice enthalpy of formation endo or exothermic?

A

Exothermic (-ive)

32
Q

Lattice enthalpy of formation of magnesium chloride?

A

Mg^2+(g) + 2Cl^-(g) —-> MgCl2(s)

33
Q

Define lattice enthalpy of dissociation

A

Enthalpy change when 1 mole of a solid ionic compound is broken up into its constituent ions in the gas phase

34
Q

Is lattice enthalpy of dissociation endo or exothermic?

A

Endothermic (+ive)

35
Q

Lattice enthalpy of dissociation of magnesium chloride?

A

MgCl2(s) —-> Mg^2+(g) + 2Cl^-(g)

36
Q

Define enthalpy of vaporisation

A

Enthalpy change when 1 mole of a liquid is turned into a gas

37
Q

Is enthalpy of vaporisation endo or exothermic?

A

Endothermic (+ive)

38
Q

Enthalpy of vaporisation of water?

A

H2O(l) —–> H2O(g)

39
Q

Define enthalpy of fusion

A

Enthalpy change when 1 mole of a solid is turned into a liquid

40
Q

Is enthalpy of fusion endo or exothermic?

A

Endothermic (+ive)

41
Q

Enthalpy of fusion of Magnesium?

A

Mg(s) —-> Mg(l)