Combined Chemistry - 5.5 Flashcards

1
Q

Name the following reactions that:

a) Take in heat from the surroundings
b) Give out heat to the surroundings

A

a) Endothermic
b) Exothermic

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2
Q

Name the type of reaction used in self-heating cups and hand warmers.

A

Exothermic reaction

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3
Q

Give an example of a chemical reaction that is exothermic.

A

Examples include: Combustion, Oxidation, Neutralisation

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4
Q

How do you know the reaction profile below is for an exothermic reaction?

A

Energy of products is lower than the energy of reactants

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5
Q

What can be said about the amount of energy before a chemical reaction and the amount of energy after a chemical reaction?

A

They are equal

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6
Q

Give an example of a chemical reaction that is endothermic.

A

Examples include: Thermal Decomposition and Reacting Citric Acid with Sodium hydrogencarbonate

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7
Q

Name the type of reaction is used in sports injury packs.

A

Endothermic reaction

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8
Q

How do you know the reaction profile below is for an endothermic reaction?

A

Energy of products is higher than the energy of reactants

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9
Q

Draw an energy level diagram (reaction profile) for an exothermic reaction.

A
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10
Q

What is the name for the minimum amount of energy needed for a reaction to happen?

A

Activation energy

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11
Q

Calculate the overall energy change in this reaction.

Bond energies: NN = 941 kJ/mol ; N-H = 391 kJ/mol ; H-H = 436 kJ/mol

*this is just an example, you may have to do this for any reaction. You will be given the bond energies.

A

Reactants: (6 x 391) = 2346

Products: (1 x 941) + (3 x 436) = 2249

2346 – 2249 = + 97 kJ/mol

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12
Q

Draw an energy level diagram (reaction profile) for an endothermic reaction.

A
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13
Q

Look at the reaction profiles below. Which arrows show the activation energy and which arrows show the overall energy change?

A
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