Bond Energies and Hydrogen Fuel Cells Flashcards Preview

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Flashcards in Bond Energies and Hydrogen Fuel Cells Deck (20)
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1
Q

What do endothermic reactions involve?

A

Bond breaking.

2
Q

What do exothermic reactions involve?

A

Bond forming.

3
Q

Is energy supplied or released for/by bond forming?

A

Released.

4
Q

Is energy supplied or released for/by bond breaking?

A

Supplied.

5
Q

How can the energy released by a chemical reaction be measured?

A
  1. Measure temperature
  2. Mix in polystyrene cup
  3. Measure temperature
6
Q

What are the problems with energy measurements?

A

Amount of energy lost to surroundings.

7
Q

How can the problems with energy measurement be solved?

A
  1. Beaker of cotton wool

2. Lid on cup

8
Q

What is the disadvantage of burning fuels?

A

It causes climate change.

9
Q

Why is it expensive to slow down the effects of climate change?

A

Alternative energy costs money to develop.

10
Q

Why does the price of crude oil have such a large economic effect?

A

Everything that’s transported by vehicles will be get more expensive as crude oil does.

11
Q

What is calorimetry?

A

Burning fuels and using the flame to heat up water.

12
Q

In exothermic reactions, is the deltaH positive or negative?

A

Negative.

13
Q

In endothermic reactions, is the deltaH positive or negative?

A

Positive.

14
Q

What is activation energy?

A

The minimum energy needed by reacting particles to break their bonds.

15
Q

How do catalysts affect the activation energy?

A

They provide a different reaction that has a lower activation energy.

16
Q

What is the advantage of hydrogen fuel cells?

A

No pollution, just water.

17
Q

What are the disadvantages of hydrogen fuel cells?

A
  1. Special expensive engine
  2. Other energy source needed to produce hydrogen
  3. Hard to store safely - explosive
  4. Needs more space than liquid fuels
18
Q

What is a fuel cell?

A

An electrical cell that’s supplied with a fuel and oxygen and uses energy from the reaction between them to generate electricity.

19
Q

What were fuel cells originally developed for?

A

Space craft in the 1960s.

20
Q

What are the advantages of fuel cells?

A
  1. More practical than solar cells
  2. Safer than nuclear power
  3. Doesn’t need recharging