Practicals

Question 1

Practical for investigating the solubility of a solid in water at different temperatures

Answer 1

• pour 200cm^3 of deionised water into a 250cm^3 beaker
• use a water bath to heat the beaker of water to a desired temperature. Keep thermometer in the beaker to ensure temperature stays constant
• add known masses of the solid bit by bit until the solid stops dissolving and remains as solid in the solution
• record the mass of the solid that was soluble
  Repeat steps 1-4 for different temperatures

Question 2

Finding the formula of a metal oxide experimentally

Answer 2

• weigh crucible lid and crucible
• place the magnesium ribbon in the crucible, replace lid and reweigh
• calculate mass of magnesium
• heat crucible with lid on until the magnesium burns
• lift lid from time to time to allow oxygen in
• Stop heating when there is no more sign of reaction
• allow to cool and reweigh
• repeat the heating, cooling and re weighing until two consecutive masses are the same
• calculate mass of magnesium oxide formed

Question 3

Calculating experimental masses using experimental data and chemical equations

Answer 3

• calculate amount of x in moles
• deduce the amount of moles in y produced from amount of moles in x by using the ratio
• calculate the mass of the amount of moles in y

Question 4

Test for displacement, dissolving and neutralisation reactions

Answer 4

1. Ass 50cm3 of copper (II) sulfate into a polystyrene cup
2. The initial temp of the copper sulfate solution is measured and recorded
3. Magnesium is added and the maximum temperature is measured and recorded
4. The temperature rise is then calculated

Question 5

Test for combustion reactions

Answer 5

1. Initial mass of ethanol and spirit burner is measured and recorded
2. 100cm3 of water is transferred into a copper container and the initial temp is measured and recorded
3. The burner is places under the copper container and then lit
4. The water is stirred constantly until temperature rises by 30C
5. The flame is extinguished and the maximum temperature of the water is measured and recorded
6. The burner and the remaining ethanol is reweighed

Question 6

Marble chips and hydrochloric acid

Answer 6

• Marble chips of different sizes are reacted with hydrochloric acid to produce carbon dioxide
• At different points in the reaction mass loss is recorded and then plotted on a graph to represent rate of reaction
• cotton wool is placed in top of beaker to prevent acid from spraying out but to allow carbon dioxide to escape

Question 7

Prepare a sample of an ester such as ethyl ethanoate

Answer 7

• Heat a mixture of ethanoic acid and ethanol
• add a few drops of sulfuric acid for the reaction to work
• in this case, the sulphuric acid is the catalyst
• a liquid called ethyl ethanoate will be formed
• this reaction is reversible