Paper 1 required practical's (will come up)

Question 1

How to prepare a pure, dry sample of a soluble salt from an insoluble oxide or carbonate

Answer 1

1. Add excess solid base to acid in a beaker (excess to ensure all acid has reacted)
2. Gently warm the mixture on a bunsen burner, stirring it
3. Filter mixture into an evaporating basin
4. Gently warm to evaporate some solution (concentrating the filtrate) using a water bath
5. Leave to cool to crystallise (slow crystallisation produces hydrated crystals; if solution was evaporated rapidly, only anhydrous powder would form)
6. Pat crystals dry with filter paper

Question 2

Method for a titration

Answer 2

1. Pour a solution into a burette, using a funnel
2. Remove funnel & take a reading
3. Pipette the other solution into a conical flask
4. Add a few drops of indicator
5. Add solution from burette to flask, whilst swirling, until the end point is reached (indicator changes colour to show reaction is complete)
6. Note volume. Calculate difference between the two readings to find the actual volume added (a titre)
7. Repeat several times until two concordant titres are obtained (two titres <= 0.10cm 3 difference)
8. Only concordant titres are used in calculating the mean

Question 3

What do burettes allow us to do

Answer 3

burettes allow a variable volume to be accurately measured

Question 4

What do pipettes allow us to do

Answer 4

pipettes allow a single volume to be accurately

measured

Question 5

What does the indicator phenolpthalein show

Answer 5

Phenolpthalein

Acid colour - Colourless

Base colour - Pink (magenta)

End point - Pale pink (if base added to acid in flask)
Colourless (if acid added to base in flask

Question 6

What does the indicator methyl orange show

Answer 6

Methyl orange
Acid colour - Red

Base colour - Yellow

End point - Orange

Question 7

Why does temperature practical take place in a polystyrene cup

Answer 7

It is used because polystyrene is an insulator:

Question 8

What does the cup do in an exothermic reaction

Answer 8

exothermic reactions: cup reduces heat loss to surroundings, giving a more accurate temperature rise

Question 9

What does the cup do in an endothermic reaction

Answer 9

endothermic reactions: cup reduces heat gain from the surroundings, giving a more accurate temperature fall

Question 10

“How does the concentration of sodium hydroxide affect the temperature rise when it reacts with acid?”
eg reaction of hydrochloric acid, HCl & sodium hydroxide, NaOH (an alkali)
The variables

Answer 10

1. Measure 20 cm 3 of HCl into polystyrene cup & record acid temperature
2. Measure 20 cm 3 of NaOH & record its temperature
3. Pour NaOH into the acid & stir
4. Record highest temperature reached
5. Repeat above steps twice & calculate mean temperature rise
6. Repeat above steps for different concentrations of NaOH

IV - concentration of alkali
DV - temperature rise
CV - same volume of acid 
same concentration of acid
same total volume of alkali
constant room temperature

Question 11

“How does the mass of carbonate affect the temperature rise when it reacts with acid?”
eg reaction of calcium carbonate & HCl
With variables

Answer 11

1. Measure 20 cm 3 of HCl into polystyrene cup & record acid temperature
2. Measure 0.50 g of carbonate, add to the acid & stir
3. Record highest temperature reached
4. Repeat above steps twice & calculate mean temperature rise
5. Repeat above steps for 1.00 g, 1.50 g, 2.00 g & 2.50 g of solid

Variables
IV - mass of solid
DV - temperature rise
CV - same volume of acid
same concentration of acid
constant room temperature

Question 12

“How does the mass of Mg affect the temperature rise when it reacts with acid?”
eg reaction of magnesium & HCl
With variables

Answer 12

1. Measure 20 cm 3 of HCl into polystyrene cup & record acid temperature
2. Measure 0.50 g of Mg, add to the acid & stir
3. Record highest temperature reached
4. Repeat above steps twice & calculate mean temperature rise
5. Repeat above steps for 1.00 g, 1.50 g, 2.00 g & 2.50 g of solid

Variables
IV - mass of solid
DV - temperature rise
CV - same volume of acid
same concentration of acid
constant room temperature

Question 13

“How does the mass of metal affect the temperature rise when it reacts with a salt solution”
eg reaction of Zn & copper sulphate
With variables

Answer 13

1. Measure 20 cm 3 of copper sulphate into polystyrene cup & record solution temperature
2. Measure 0.50 g of Zn, add to solution & stir
3. Record highest temperature reached
4. Repeat above steps twice & calculate mean temperature rise
5. Repeat above steps for 1.00 g, 1.50 g, 2.00 g & 2.50 g of solid

Variables
IV - mass of solid
DV - temperature rise
CV - same volume of solution
same concentration of solution
constant room temperature