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Higher Chemistry > Sub Topic 2 - Enthalpy > Flashcards

Sub Topic 2 - Enthalpy Flashcards

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1
Q

Endothermic changes cause heat to be

A

released to the surroundings

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2
Q

Endothermic changes cause absorption of

A

heat from the surroundings

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3
Q

A potential energy diagram can be used to show

A

the energy path for a reaction

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4
Q

The enthalpy change is the energy difference between

A

products and reactants

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5
Q

The enthalpy change can be calculated from a

A

potential energy diagram

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6
Q

The enthalpy change for an exothermic reaction is

A

negative

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7
Q

The enthalpy change for an endothermic reaction is

A

positive

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8
Q

The activated complex is an

A

unstable arrangement of atoms

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9
Q

The activated complex is formed at the

A

maximum of the potential energy barrier during a reaction.

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10
Q

The activation energy is the energy required by

A

colliding molecules to form an activated complex

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11
Q

The activation energy can be calculated from

A

potential energy diagrams

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12
Q

A potential energy diagram can be used to show the effect of a catalyst on

A

activation energy

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13
Q

An example of an exothermic reaction is

A

thermite Reaction

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14
Q

During an exothermic reaction what happens to the temperature of the surroundings ?

A

It rises because heat is being given out

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15
Q

In enthalpy terms ‘the surroundings’ means

A

the container, the air around about, the reactant mixture itself.

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16
Q

In an exothermic reaction heat energy is

A

released to the surroundings

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17
Q

In an endothermic reaction heat is

A

absorbed from the surroundings

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18
Q

Bond breaking is

A

Endothermic as energy is taken in

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19
Q

Bond making is

A

Exothermic (gives energy out)

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20
Q

During an exothermic reaction, potential energy possessed by the reactants is

A

released to the surrounds

21
Q

The products of an exothermic reaction have _____ potential energy than the reactants

A

LESS

22
Q

The products of an endothermic reaction have ______ potential energy than the reactants

A

MORE

23
Q

The enthalpy change is the difference in energy between

A

reactants and products

24
Q

The enthalpy change has the symbol

A

∆H

25
Q

The enthalpy change can be expressed as

A

∆H = Hp - Hr

26
Q

Hp = the enthalpy of the

A

products

27
Q

Hr = the enthalpy of the

A

reactants

28
Q

This potential energy diagram is one of a ______ reaction

A

Exothermic

29
Q

This potentail energy digram is one of a _______ reaction

A

Endothermic

30
Q

Area Y is

A

∆H

31
Q

Area X is

A

Ea

32
Q

In an exothermic reaction the reactants are______ than the products

A

Higher

33
Q

In an endothermic reaction the reactants are _______ lower than the products

A

lower

34
Q

For an exothermic reation the enthalpy change calculation is

A

∆H = Hp - Hr

= Small number - Large number

= negative

35
Q

In an endothermic reaction the enthalpy calculation is

A

∆H = Hp-Hr

= Large number - small number

= positive

36
Q

A catalyst decreases the

A

activation energy of a reaction

37
Q

Which line shows the exothermic reaction without a catalyst? Green or Red

A

Green

38
Q

A catalyst speeds up a reaction by ________ the activation energy

A

decreasing

39
Q

The enthalpy of combustion of a substance is the enthalpy change when

A

one mole of the substance burns completely in oxygen

40
Q

The enthalpy of solution of a substance is the energy change

A

when one mole of a substance dissolves in water.

41
Q

The enthalpy of neutralisation of an acid is the enthalpy change when

A

the acid is neutralised to form one mole of water

42
Q

The enthalpy changes can be calculated using the formula”

A

Eh= cm ∆T

43
Q

Enthalpy of Combustion: The energy change when

A

one mole of a substance burns completely in oxygen

44
Q

Eh = cm∆T the C represents the

A

specific heat capacity of water = 4.18 kj

45
Q

Eh = cm∆T the m represents the

A

mass of water in kg

46
Q

Eh = cm∆T the ∆T represents the

A

the temperature change in C°

47
Q

The Enthalpy of Solution: The energy change when

A

one mole of a substance dissolves compeltely in water

48
Q

The Enthalpy of Neutralisation: The Enthalpy of Neutralisation is the energy change when

A

one mole of water is formed in a neutralisation reaction.

Higher Chemistry (3 decks)

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