How Much? (not Maths)

Question 1

Give an example of a reversible reaction

Answer 1

Thermal decomposition of ammonium chloride

Question 2

What are food additives?

Answer 2

Substances that are added to improve the quality of food

Question 3

What methods can be used to amylose the colours in food?

Answer 3

Paper chromatography and mass spectrometry

Question 4

How does paper chromatography work?

Answer 4

A spot of colour is put onto paper and a solvent is allowed to move through the paper the colours move distances depending on their solubility

Question 5

Why are modern instrumental methods of analysis often used?

Answer 5

They are very:
rapid
Accurate
Sensitive

Question 6

What are the DisAds of instrumental analysis?

Answer 6

Equipment is very expensive and special training is required to use it

Question 7

What is a reversible reaction?

Answer 7

When the products of a chemical reaction can react to reform the products

Question 8

How may you identify the Compounds in a sample?

Answer 8

Gas chromatography

Question 9

What happens in gas chromatography?

Answer 9

The mixture is carried by a gas through a long column each compound travels at different speeds leaving the column at different times. Their retention times are recorded which can be compared to indenting the compounds

Question 10

What is the main purpose of the gas chromatography column in GC-MS analysis?

Answer 10

To separate the compounds in the mixture

Question 11

What can a mass spectrometer give?

Answer 11

The relative molecular mass of a compound

Question 12

What is the peak called?

Answer 12

The molecular ion peak

Question 13

The individual compound with the peak with the largest mass corresponds to what?

Answer 13

The ion with just on electron removed

Question 14

How is the relative molecular mass shown in a mass spectrum?

Answer 14

From the molecular ion peak or the peak with the largest mass (furthest to the right of the spectrum)

Question 15

Why is it not usually possible to get 100% yield from a chemical reaction?

Answer 15

Reactions may not go to completion, other reactions may happen, some product may be lost when separated or collected

Question 16

Why should chemical manufactures use reactions with high yield?

Answer 16

To help conserve resources, reduce waste and pollution

Question 17

What is the yield of a chemical reaction?

Answer 17

How much is actually made

Question 18

Why do we only count protons and neutrons to calculate the mass number of an atom?

Answer 18

The mass of an electron is very small compared to that of a proton or neutron

Question 19

How many protons neutrons and electrons are there in an atom of
19
F
9

Answer 19

9 protons
9 electrons
10 neutrons

Question 20

What are isotopes?

Answer 20

Atoms of the same element of atoms with the same atomic proton numbers that have different numbers of neutrons

Question 21

What is a mole?

Answer 21

The relative atomic mass of an element in grams

Question 22

What do we compare the masses of all the other atoms with?

Answer 22

Carbon-12

Question 23

What is the mass of 1 mole of sodium atoms?

Answer 23

23g

Question 24

Why is the relative mass of chlorine not a whole number?

Answer 24

It has 2 main isotopes and the relative atomic mass is an average value

Question 25

What is the empirical formula?

Answer 25

The simplest ratio of the atoms or ions in a compound