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GSHS C2 Chemistry > C2 Revision > Flashcards

Flashcards in C2 Revision Deck (24)
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1
Q

What is the relative mass of a neutron?

A

1

2
Q

What is an atoms mass number?

A

The number of protons and neutrons in the nucleus.

3
Q

What is an isotope?

A

An element with the same number of protons but different number of neutrons

4
Q

Calculate the relative formula mass for carbon dioxide (CO2)

A

12+16+16 = 44

5
Q

What is meant by the term mole?

A

The relative formula mass of a substance in grams is one mole.

One mole = 6.022 x 10^23 atoms or molecules

6
Q

Calculate the percentage by mass of carbon in carbon dioxide.

A

Ar of carbon = 12
Mr of CO2 = 44
(12/44)x100 = 27.3 %

7
Q

How many atoms of sodium react with 1 molecule of chlorine to make two sodium chlorides? (2Na + Cl2 -> 2NaCl)

A

2

8
Q

What is meant by the term yield?

A

The amount of useful product obtained from a reaction

9
Q

Give reasons to explain why the yield of a reaction may be less than expected.

A
  1. Reaction may be incomplete
  2. Some product is lost
  3. Other unwanted reactions may occur making a different product.
  4. Reaction may be reversible
10
Q

What is chromatography used for?

A

Separate mixtures

11
Q

Give an advantage and a disadvantage for using gas chromatography over paper chromatography.

A

Advantages = rapid, accurate, sensitive. Disadvantages = expensive.

12
Q

What is a mass spectrometer used for?

A

Identify substances or measure a compounds relative molecular mass

13
Q

How do you work out the rate of a reaction?

A

Rate of reaction = amount of reactant used or product formed / time

14
Q

What two things needs to happen for particles to react?

A

Collide with enough energy

15
Q

State 4 ways to speed up a chemical reaction

A

Increase concentration, increase temperature, increase surface area and use a catalyst

16
Q

Why do catalysts not need to be replaced?

A

They are not used up during a chemical reaction.

17
Q

What is the difference between exothermic and endothermic reactions?

A

Exothermic gives out heat (temperature increases) endothermic takes in heat (temperature decreases)

18
Q

Give a use for exothermic reactions

A

Self heating cans / hand warmers

19
Q

In a reversible reaction 500 J of energy is released in the forward reaction. What happens in the reverse reaction?

A

500 J of energy is absorbed.

20
Q

What is the pH of an acid?

A

1-6

21
Q

What is the atomic number of magnesium?

A

12

22
Q

Calculate the relative atomic mass of water (H2O)

A

H=1, O=16

1+1+16 = 18

23
Q

How many atoms of Calcium react with 1 molecule of chlorine to make calcium chloride (Ca + Cl2 -> CaCl2)

A

1 atom

24
Q

Calculate the percentage mass of oxygen in water

A

Ar of oxygen = 16
Mr of water = (1 + 1 + 16) = 18
(16/18) x 100 = 88.9%