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GSHS C2 Chemistry > C2 Revision > Flashcards

Flashcards in C2 Revision Deck (24):
1

What is the relative mass of a neutron?

1

2

What is an atoms mass number?

The number of protons and neutrons in the nucleus.

3

What is an isotope?

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

4

Calculate the relative formula mass for carbon dioxide (CO2)

12+16+16 = 44

5

What is meant by the term mole?

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

One mole = 6.022 x 10^23 atoms or molecules

6

Calculate the percentage by mass of carbon in carbon dioxide.

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

7

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

2

8

What is meant by the term yield?

The amount of useful product obtained from a reaction

9

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

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

What is chromatography used for?

Separate mixtures

11

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

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

12

What is a mass spectrometer used for?

Identify substances or measure a compounds relative molecular mass

13

How do you work out the rate of a reaction?

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

14

What two things needs to happen for particles to react?

Collide with enough energy

15

State 4 ways to speed up a chemical reaction

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

16

Why do catalysts not need to be replaced?

They are not used up during a chemical reaction.

17

What is the difference between exothermic and endothermic reactions?

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

18

Give a use for exothermic reactions

Self heating cans / hand warmers

19

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

500 J of energy is absorbed.

20

What is the pH of an acid?

1-6

21

What is the atomic number of magnesium?

12

22

Calculate the relative atomic mass of water (H2O)

H=1, O=16
1+1+16 = 18

23

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

1 atom

24

Calculate the percentage mass of oxygen in water

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