Paper 1 Required Practical's

Question 1

Required Practical 1: Preparation of a Soluble Salt

Aim and Hypothesis

Answer 1

Objective:

To prepare a pure, dry sample of a soluble salt from an insoluble oxide or carbonate using a Bunsen burner and dilute acid

Hypothesis:

A salt can be prepared and separated by an acid-base neutralisation reaction

Question 2

Required Practical 1: Preparation of a Soluble Salt

Method

Answer 2

1. Add 50cm³ dilute acid into a beaker and warm gently using a Bunsen burner
2. Add the insoluble oxide slowly to the hot dilute acid and stir until the base is in excess (i.e. until the base stops dissolving and a suspension of the base forms in the acid)
3. Filter the mixture into an evaporating basin to remove the excess base
4. Gently heat the solution in a water bath or with an electric heater to evaporate the water and to make the solution saturated
5. Check the solution is saturated by dipping a cold glass rod into the solution and seeing if crystals form on the end
6. Leave the filtrate in a warm place to dry and crystallise
7. Decant excess solution and allow the crystals to dry

Question 3

Required Practical 1: Preparation of a Soluble Salt

Results, Hazards and Conclusion

Answer 3

Results:

Hydrated copper(II) sulfate crystals should be bright blue and regularly shapedEvaluation:

Describe how your crystals compare to the description in the results section. If different suggest an explanation

Conclusion:

Acid-base reactions produce salt and water with the regular shape of the salt reflecting the ionic lattice structure in its bonding

Question 4

Required Practical 2: Strong Acid & Strong Alkali Titration

Objectives, Hypothesis and Materials

Answer 4

Objective:

To determine the reacting volumes of a strong acid and a strong alkali by titration

Hypothesis:

The titration method can be used to calculate the concentration of an acid

Materials:

• 25 cm³ volumetric pipette
• Pipette filler
• 50 cm³ burette
• 250 cm³ conical flask
• Small funnel
• 0.1 mol/dm³ sodium hydroxide solution
• Sulfuric acid – concentration unknown
• Phenolphthalein indicator
• Clamp stand, clamp & white tile

Question 5

Required Practical 2: Strong Acid & Strong Alkali Titration

Method

Answer 5

Make sure you remove the funnel after filling the burette as if left it can drop solution into the burette, leading to error

Method:

1. Use the pipette and pipette filler and place exactly 25 cm³ sodium hydroxide solution into the conical flask
2. Place the conical flask on a white tile so the tip of the burette is inside the flask
3. Add a few drops of a suitable indicator to the solution in the conical flask
4. Perform a rough titration by taking the burette reading and running in the solution in 1 – 3 cm³ portions, while swirling the flask vigorously
5. Quickly close the tap when the end-point is reached (sharp colour change) and record the volume, placing your eye level with the meniscus
6. Now repeat the titration with a fresh batch of sodium hydroxide
7. As the rough end-point volume is approached, add the solution from the burette one drop at a time until the indicator just changes colour
8. Record the volume to the nearest 0.05cm³
9. Repeat until you achieve two concordant results (two results that are within 0.1cm³ of each other) to increase accuracy

Question 6

Required Practical 2: Strong Acid & Strong Alkali Titration

Answer 6

Results: Record your results in a suitable table, e.g:

Evaluation:

Only concordant results should be used to calculate a mean titre

Conclusion:

The mean titre is calculated and used to calculate the concentration of the acid in mol/dm³, ignoring any anomalous results

Question 7

Required Practical 4: Investigating Temperature Changes

Objectives, Hypothesis & Materials

Answer 7

Objective:

To perform a calorimetry study of the reaction between HCl and NaOH

Hypothesis:

The temperature change will vary depending on the amounts of solutions involved

Materials:

• Dilute hydrochloric acid
• Dilute sodium hydroxide solution
• Styrofoam (polystyrene) calorimeter & lid
• 25 cm³ measuring cylinder
• Thermometer & stirrer

Question 8

Required Practical 4: Investigating Temperature Changes

Method, results and Evaluation

Answer 8

Method:

Reacting two solutions, eg acid and alkali

1. Place the polystyrene cup inside the glass beaker to make it more stable.
2. Measure an appropriate volume of each liquid, eg 25 cm³.
3. Place one of the liquids in a polystyrene cup.
4. Record the temperature of the solution.
5. Add the second solution and record the highest or lowest temperature obtained.
6. Change your independent variable and repeat the experiment. Your independent variable could be the concentration of one of the reactants, or the type of acid/alkali being used, or the type of metal/metal carbonate being used.

Method

Reacting a solid with a solution, eg metal and acid

1. Place the polystyrene cup inside the glass beaker to make it more stable.
2. Measure an appropriate volume of the solution, eg 25 cm³.
3. Measure an appropriate mass of the solid, or select a suitable sized piece of metal.
4. Place the solution in a polystyrene cup.
5. Record the temperature of the solution.
6. Add the solid and record the highest or lowest temperature obtained.
7. Change your independent variable and repeat the experiment. Your independent variable could be the surface area of the solid, or the type of acid being used, or the type of metal being used.

Results:

Record your results in a suitable table, eg:

Evaluation:

Plot a graph of the results and draw a line of best fit, using the graph to determine what volume of acid causes the biggest change in temperature

Conclusion:

The larger the difference in the temperature the more energy is absorbed or released

Question 9

Required Practical 4: Investigating Temperature Changes

Hazards, risks and precautions

Answer 9