C7 Flashcards

1
Q

Draw an exothermic reaction profile?

A

draw

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2
Q

Draw an endothermic reaction profile?

A

draw

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3
Q

draw an electrolysis cell?

A

draw

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4
Q

Advantages of hydrogen fuel cells

A
  • They will produce electricity for as long as you provide hydrogen
  • Hydrogen fuel cells do not get less efficient the longer they run
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5
Q

Bond Energy Formula?

A

energy change = sum of the energy needed to break bonds (reactants) - energy released when new bonds are formed (products)

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6
Q

Characteristics of fuel cells?

A
  • reliable
  • efficient
  • compact and lightweight
  • not very polluting
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7
Q

Disadvantages of hydrogen fuel cells

A
  • Highly Explosive
  • They produce a relatively low potential difference or voltage so several are needed together
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8
Q

Electrolysis and photosynthesis is an example of a _____.

A

endothermic reaction

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9
Q

Example of a endothermic reaction

A

citric acid + sodium hydrogencarbonate

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10
Q

Example of reactive profile diagram with catalyst

A

draw

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11
Q

How can rechargeable batteries be recharged?

A

The chemical reactions can be reversed when an electrical current is applied.

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12
Q

How does the reactivity of the metals link to the potential difference of the metals?

A

The greater the difference between the reactivity of the metals, the greater the potential difference produced by the cell.

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13
Q

How is a electrochemical cell set up?

A

1) 2 electrodes which are metals as they must conduct electricity
2) The electrolyte is a liquid that contains ions
3) Wire connecting the 2 electrodes

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14
Q

If the energy change on an energy level diagram is negative, is this an endothermic or exothermic reaction?

A

Exothermic reactions have a negative energy change because they release/lose energy.

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15
Q

In an ____ reaction, the energy of the reactants is higher than the energy of the products.

A

exothermic

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16
Q

In exothermic reactions the energy released by forming bonds is ____ than the energy used to break them.

A

greater

17
Q

Is bond breaking endothermic or exothermic?

A

endothermic

18
Q

Melting is an example of an _____.

A

Endothermic reaction. Energy is taken in from the surroundings.

19
Q

Name 2 different types of reactions which are exothermic

A
  • Neutralisation
  • Combustion
20
Q

Types of batteries

A
  • rechargeable
    = non-rechargeable
21
Q

What can we do to change the voltage output of a cell?

A
  • change the electrodes
  • change the electrolyte
22
Q

What do catalysts do to the activation energy?

A

Catalysts increase reaction rates by lowering the activation energy

23
Q

What is a battery?

A

A battery contains 2 or more cells connected in series, to produce a greater voltage.

24
Q

What is a chemical cell?

A

A chemical cell is a source of electrical energy.

25
Q

What is a fuel cell?

A

A fuel cell is an electrical cell that’s supplied with a fuel and oxygen which uses energy from the reaction between them to provide electrical energy efficiently.

26
Q

What is a reaction profile diagram?

A

Reaction profiles are diagrams that show the energies of the reactants and products in a reaction and how they change over the course of the reaction.

27
Q

What is activation energy?

A

Activation energy is the amount of energy required to start a chemical reaction

28
Q

What is an electrolyte?

A

A solution that can conduct electricity, usually an ionic compound

29
Q

What is an endothermic reaction?

A

An endothermic reaction is a reaction where energy is drawn in from the surroundings, causing the surroundings and object to cool down.

30
Q

What is an exothermic reaction?

A

An exothermic reaction is a reaction which cools itself down, giving heat to the surroundings.

31
Q

What is an instant cold ice pack an example of?

A

An endothermic process

32
Q

What is the only waste product in a hydrogen fuel cell?

A

water

33
Q

What type of process is the breaking of existing bonds?

A

endothermic

34
Q

What type of process is the forming of new bonds?

A

exothermic

35
Q

Which energy resource uses falling water to generate electricity?

A

Hydroelectricity

36
Q

Why are fuel cells reliable?

A

They have no moving parts

37
Q

Why can alkaline batteries not be recharged?

A

The reaction isnt reversible

38
Q

Why do alkaline batteries eventually stop working?

A

A reactant is used up