C6: Chemical Synthesis

Question 1

Name two chemicals you might come across in everday life

Answer 1

Cleaning products, paints, dyes, fertillisers, food additives, drugs.

Question 2

Give an example of a chemical made on a small scale

Answer 2

Pharmaceticals are produced on a smaller scale.

Question 3

Give an example of chemicals made on a large scale

Answer 3

Sulfuric acid

Question 4

State whether the following are acid, alkali or neutral.
pH 2
pH 13
pH 0
pH 7

Answer 4

ACID
ALKALI
ACID
NEUTRAL

Question 5

Give an example of a pure acidic compound that is a liquid

Answer 5

Nitric acid, sulfuric acid, ethanoic acid

Question 6

Give two ways of measuring the pH of a substance

Answer 6

Litmus paper, Universal indicator with a pH scale & pH meters

Question 7

What types of ions are always present in a) acid b) alkalis dissolved in water

Answer 7

a) H+

b) OH-

Question 8

Write the equation for the ions in acids and alkalis

Answer 8

H+ + OH- —-> H2O

Question 9

When designing a chemical process what is involved in carrying out a risk assesment?

Answer 9

Identifying hazards, assesing who could be harmed & deciding what action should be taken to reduce risk

Question 10

What does calculating the yield tell you about a reaction?

Answer 10

Tells you the overall sucess of the process

Question 11

How would you seperate an insouble product from a liquid reaction mixture?

Answer 11

Filtration

Question 12

Name two stages in synthesis of a chemical where evaporation can be useful

Answer 12

Isolating the product and purification

Question 13

Give two methods used to dry a product

Answer 13

Dried in a drying oven or a desiccator

Question 14

What is the formula for percentage yield?

Answer 14

Actual yield divided by theoretical yield x 100

Question 15

Why is purifciation of a product important?

Answer 15

Important in production of pharmaceuticals, impurities could do more harm than good. Also in petrochemicals impurites could cause damage to the cars engine.

Question 16

DEFINE: Endothermic

Answer 16

A reaction which takes in energy from the surroundings, usually in the form of heat and shown by a fall in temperature

Question 17

DEFINE: Exothermic

Answer 17

A reaction which gives out energy to the surrondings, usually shown by a rise in temperature

Question 18

Give two reasons why it is important to control the rate of reaction in industry

Answer 18

If the reaction mixture gets too hot, the reactants or product could become gasees, which could increase pressure and cause an explosion.
If the reaction is endothermic heats needs to be supplied otherwise it will be to cold for the reaction to take place& equipment could be damaged by freezing

Question 19

What four things affect rate of reaction?

Answer 19

Temperature
Concentration
Surface Area
Use of enzyme/Catalyst

Question 20

Give three ways you could mesure rate of reaction

Answer 20

1) Precipitation and colour change
2) Change in Mass
3) Volume of gas given off

Question 21

Give an advantage and disavantage of the Preciptation and Colour change method

Answer 21

Works for reactions where the inital solution is see-through
Results are very subjective, different people might not agree on the exact point where the mark disappears of the solution changes colour

Question 22

Give an advantage and disadvantage of the Change in Mass method

Answer 22

Rate of reatciongraphs are easy to plot using results from this data and is the most accurate.
Disadvantage is it releases the gas straight into the room

Question 23

Give an advantage and disadvantage of the Volume of gas method

Answer 23

Gas syringes will give a fairly accurate result to nearest cm3.
Disadvantage if the reaction is too vigorous the plunger could easily blow of the end.