Chemistry Energy Changes Sept 2018 Flashcards

1
Q

What is an exothermic reaction?

A

A reaction in which thermal energy is transferred from the chemicals to the surroundings and so the temperature increases

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2
Q

What is an endothermic reaction?

A

A reaction in which thermal energy is transferred from the surroundings to the chemicals and so the temperature decreases

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3
Q

What is an application of an exothermic reaction?

A

Hand warmers and instant heat packs use exothermic reactions to heat up quickly

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4
Q

What is an application of an endothermic reaction?

A

Instant cold packs use endothermic reactions to cool down quickly

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5
Q

What is activation energy?

A

The minimum amount of energy that particles need to react.

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6
Q

In exothermic reactions is the energy of the product higher or lower than the reactants? (Remember the graphs)

A

Lower

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7
Q

In endothermic reactions is the energy of the product higher or lower than the reactants? (Remember the graphs)

A

Higher

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8
Q

What is required to break bonds?

A

Energy

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9
Q

What two things occur in a chemical reaction? (In terms of bonds)

A
  • energy must be supplied to break bonds between
    reactants.
  • energy will be released when bonds are made
    between the products.
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10
Q

What is the overall energy change?

A

The difference between energy to break the bonds in the reactants & the energy made when bonds are made between products

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11
Q

What is the equation for energy change?

A

energy needed to break bonds in the reactants - energy released when bonds are made by the products

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12
Q

What is a cell?

A

Two electrodes in an electrolyte used to generate electricity

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13
Q

What is a battery?

A

Two or more cells connected in series

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14
Q

What is an electrolyte?

A

A liquid that contains electricity

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15
Q

What two factors affect the voltage of cells?

A

The metals: The identity matters. The greater the difference in reactivity, the greater the voltage.
The electrolyte: Changing the electrolyte and/or the concentration can affect the voltage

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16
Q

What are non-chargeable batteries?Examples?

A

Batteries in which the chemical reactions can’t be undone making it non-chargeable. Alkaline & lithium button cells are some examples.

17
Q

What is a chargeable batteries? Examples?

A

Batteries in which the chemical reactions can be undone making it chargeable. Phone and tablet batteries are some examples.

18
Q

What is a fuel cell?

A

A chemical cell with a continuous supply of chemicals to fuel the cell