Enthalpy Flashcards

1
Q

What is enthalpy?

A

The energy content of a substance (taken as a measurement of the heat content).

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2
Q

Exothermic reaction

A

Reaction in which energy is given out.

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3
Q

Endothermic reaction

A

Reaction in which energy is taken in.

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4
Q

What is activation energy?

A

The energy required by colliding molecules to create an activated complex

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5
Q

What is an activated complex?

A

An unstable arrangement of atoms which can result in the formation of the product or reverse back to the reactants.

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6
Q

Effect of a catalyst:

A

providing alternative pathways for a reaction which have a lower activation energy.

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7
Q

Catalyst of the same state as the reactants:

A

homogeneous

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8
Q

Catalyst in a different state of the reactants:

A

heterogeneous.

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9
Q

catalysts do not

A

affect the change in enthalpy.

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10
Q

Definition of enthalpy of combustion of a substance

A

is the enthalpy change when one mole of the substance burns completely in oxygen.

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11
Q

Definition of enthalpy of solution of a substance

A

is the enthalpy change when one mole of the substance dissolves in water.

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12
Q

Enthalpy of neutralisation of an acid

A

is the enthalpy change when the acid is neutralised to form one mole of water.

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13
Q

Potential energy diagram can be used to show

A

the enthalpy change of a reaction.

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14
Q

in terms of energy enthalpy change is

A

the difference between potential energy levels.

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15
Q

draw the effect of a catalyst in a reaction on a graph

A

activation energy would be lower the rest is the same

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16
Q

what equation can be used to calculate enthalpy changes?

A

E= cm(t-t)

(t-t0 = delta T