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Chemistry Unit 1 > 2 Energetics and Enthalpy Changes > Flashcards

2 Energetics and Enthalpy Changes Flashcards

0
Q

What is the definition for the standard enthalpy change?

A

The enthalpy change that happens when one mole of a substance is completely combusted in oxygen under standard conditions

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1
Q

What does effervescence mean?

A

Bubbles a lot

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2
Q

What is the symbol for the standard enthalpy change of combustion?

A

C

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3
Q

When working out standard enthalpy change what are the rules?

A

First must be one mole

Can halve diatomic molecules

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4
Q

What is the definition for the standard enthalpy change of formation?

A

The enthalpy change when one mole of a compound is formed from its elements in their standard states

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5
Q

Do elements have an enthalpy change for formation?

A

Nope

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6
Q

When working out enthalpy change, what form of carbon must be used?

A

Graphite

C(graphite)

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7
Q

What is the symbol for the standard enthalpy change of formation?

A

f

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8
Q

What is the definition for the standard enthalpy change of atomisation?

A

The enthalpy change when one mole of its atoms in the gaseous state is formed from the element under standard conditions

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9
Q

What is the symbol for standard enthalpy change of atomisation?

A

at

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10
Q

Standard enthalpy changes of atomisation is and exothermic/endothermic process

A

Exothermic

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11
Q

What doesn’t have a standard enthalpy change of atomisation?

A

Noble gases

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12
Q

What is the definition of the energy change of neutralisation?

A

The enthalpy change of a reaction where one mole of acid is neutralised by an alkali in their standard states at 298K and in solutions containing 1moldm(3)

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13
Q

What is the enthalpy of neutralisation for strong acids with strong bases?

A

-58kJmol

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14
Q

What is the definition of Hess’ Law?

A

The enthalpy change is independent of the path taken

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15
Q

What happens if you the opposite way in Hess’ Law?

A

You subtract the value of the enthalpy change

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16
Q

What is ALWAYS produced as a result of combustion?

A

Carbon dioxide

Water

17
Q

What is the equation for energy change?

A

Mass (g) x specific heat capacity (JK[-1]g[-1]) x temperature change (K)

18
Q

What is the equation for working out standard enthalpy change?

A

Sum of bonds broken - sum of bonds made

Sum of enthalpy change of formation (products) - sum of enthalpy change of formation (reactants)

19
Q

What is the equation for the number of moles?

A

Mass in g/mass of 1 mile
Volume gas dm(3)/24dm(3)
Concentration x volume

20
Q

What does the term ‘enthalpy change of a reaction’ mean?

A

Heat energy that is released into the surroundings in an exothermic reaction

21
Q

What is the definition for lattice enthalpy?

A

Standard enthalpy change of formation of one mole of an ionic compound from its gaseous ions under standard conditions

22
Q

What is the definition for standard molar entropy change of atomisation?

A

The enthalpy change that takes place when one mole of gaseous atoms is formed from its elements in its standards state under standard conditions

23
Q

What is the definition of electron affinity?

A

Energy change when one mole of gaseous atoms acquire one mole of electrons to form a single negatively charged ion

24
Q

What is energetics?

A

Study on energy transfers between reacting chemicals and surroundings

25
Q

Does breaking bonds will require energy or release energy?

A

Require

26
Q

Does making bonds require or release energy?

A

Release

27
Q

Give an example of an exothermic reaction and an endothermic reaction

A

Exothermic – neutralisation

Endothermic – photosynthesis

28
Q

What is the definition for enthalpy change of reaction?

A

Exothermic reaction releases energy to the surroundings in the form of heat

29
Q

What is the system?

A

The reaction in which the changes are happening brackets products and reactants

30
Q

What is meant by the surroundings?

A

Outside the system

31
Q

What are the two sorts of boundaries and what do they prevent?

A

Closed prevents particles entering/leaving system

Isolated prevents particles and energy entering/leaving system

32
Q

What is the first law of thermodynamics?

A

Energy cannot be created or destroyed

33
Q

What happens to the energy transferred to surroundings?

A

Dissipated

34
Q

What is the principle of conservation energy?

A

The total energy content of the universe is constant

35
Q

What is the equation to work out the enthalpy change of a reaction

A
36
Q

What is the enthalpy change of an exothermic reaction?

A

Negative
H(products)< H(reactants)
Net decrease in potential energy of the system

37
Q

What is the enthalpy change of an endothermic reaction?

A

Positive
H(products)> H(reactants)
Net increase in potential energy of the system

38
Q

What does the enthalpy level diagram of an exothermic reaction look like?

A

_______

|______

39
Q

What does the enthalpy level diagram of an endothermic reaction look like?

A

_____

____|

40
Q

What is thermochemistry?

A

The study of the quantities of heat during reactions

41
Q

What does enthalpy mean?

A

The energy content of the system held at constant pressure

Represented by H

Chemistry Unit 1 (7 decks)

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