Quantitive analysis, gas volumes and fuel cells T6

Question 1

How do you calculate Concentration?

Answer 1

Concentration (mol dm-3) = number or moles / volume of solution

Question 2

What are Titrations?

Answer 2

Titrations allow you to find out exactly how much acid is needed to neutralise a given quantity of alkali (or vice versa)

Question 3

Why can you not use Universal indicator for titration?

Answer 3

Because Universal indicator changes colour gradually and you need it to have a single colour change.

Question 4

Why should you put a white tile under the flask during titrations?

Answer 4

Because the white tile makes the colour change easier to see

Question 5

How do you do Titrations?

Answer 5

Fill a burette with a standard solution (a known concentration) of acid. Use the burette to add the acid to the alkali a bit at a time. Swirl the flask regularly. The indicator colour changes colour when all the alkali has be neutralise.

Question 6

How do you convert concentration in mol dm-3 to g dm-3?

Answer 6

Concentration (mol dm-3) X Relative formula mass

Question 7

How do you work out percentage yield?

Answer 7

(Actual yield / theoretical yield) X 100

Question 8

What is atom economy?

Answer 8

Atom economy = total Mr of desired products / total Mr of all products X 100

Question 9

What happens with reactions which have low atom economy?

Answer 9

They use up resources quickly. They also produce a lot of wadte materials.

Question 10

How do you calculate moles?

Answer 10

Number of moles = mass in g (of element or compound) / Mr (of compound) or Ar (of element)

Question 11

What does Mr or Ar mean?

Answer 11

Relative particle mass

Question 12

How do you work out concentration?

Answer 12

Concentration = mass of solute / volume of solution

Question 13

What does the Haber process create?

Answer 13

The Haber process creates ammonia using: Nitrogen 1:3 Hydrogen = Ammonia + heat

Question 14

What does Ammonia do?

Answer 14

Ammonia can be reacted with oxygen and water in a series of reactions to make nitric acid. You can also react ammonia with acids, including nitric acid and phosphoric acid, to get ammonium salts.

Question 15

How does the Haber process work?

Answer 15

Higher pressures favour the forward reaction as there is 4 moles of hydrogen and nitrogen to make 2 moles of ammonia. So the pressure is set as high as possible to give the best yield. The forward reaction is exothermic, which means that increasing the temperature will move the equilibrium the wrong way and away from ammonia. So the yield of ammonia would be greater with lower temperatures. 450 degrees C

Question 16

How is equilibrium reached faster?

Answer 16

High temperatures, high pressures and high concentrations

Question 17

What are the 3 main elements in fertilisers?

Answer 17

Nitrogen, phosphorus and pottasium

Question 18

Why do ammonia fertilisers have advantages over traditional fertilisers?

Answer 18

You can control the compositions of chemicals in them, as well as how much is made.

Question 19

What is Ammonium sulphate?

Answer 19

Ammonium sulphate is a fertiliser you can make in the lab. You’ll need ammonia and dilute sulphuric acid.

Question 20

How to calculate molar volume?

Answer 20

Molar volume = gas volume / number of moles

Question 21

What is molar volume?

Answer 21

The volume occupied by one mole of gas.

Question 22

How much does one mole of gas occupy?

Answer 22

One mole of gas always occupies 24 dm3

Question 23

What are Hydrogen - Oxygen fuel cells?

Answer 23

Hydrogen and Oxygen fuel cells use Hydrogen as a fuel which mixes with oxygen to create a voltage and it doesn’t produce any nasty pollutants.