0620/61 · May/June 2026
Download PDFA student tries to make crystals of hydrated copper(II) sulfate, . Crystals of hydrated copper(II) sulfate are blue. The student makes aqueous copper(II) sulfate by reacting copper(II) carbonate with dilute sulfuric acid. The equation for the reaction is shown. The first three steps of the method the student uses are shown. step 1 Pour of dilute sulfuric acid into a beaker. step 2 Add copper(II) carbonate to the dilute sulfuric acid in the beaker until the copper(II) carbonate is in excess. step 3 Remove the excess copper(II) carbonate from the reaction mixture.
In step 2, the student observes effervescence as the copper(II) carbonate reacts with the dilute sulfuric acid. Describe one other observation that is made in step 2 before the copper(II) carbonate is in excess.
Explain why the copper(II) carbonate must be added in excess.
Figure 1.1 shows the apparatus at the end of step 3. Name the method of separation shown in Figure 1.1.
Identify the residue, A, in Figure 1.1.
Name the item of apparatus labelled B in Figure 1.1.
The student heats the aqueous copper(II) sulfate collected in the conical flask in Figure 1.1 until all the water has evaporated. The student obtains a white solid instead of blue hydrated copper(II) sulfate. Name the white solid the student obtains.
Describe what the student should do to get crystals of hydrated copper(II) sulfate from the aqueous copper(II) sulfate obtained in step 3.
A student investigates the temperature change when citric acid reacts with sodium carbonate. The student does five experiments. Experiment 1 • Use a measuring cylinder to pour of distilled water into a boiling tube. • Use a thermometer to measure the initial temperature of the distilled water. • Record this temperature to the nearest . • Add of solid citric acid and of solid sodium carbonate to the boiling tube. • Stir the contents of the boiling tube with the thermometer and measure the lowest temperature reached by the mixture. • Record this temperature to the nearest . • Rinse out the boiling tube with distilled water. Experiment 2 • Repeat Experiment 1 using of distilled water instead of . Experiment 3 • Repeat Experiment 1 using of distilled water instead of . Experiment 4 • Repeat Experiment 1 using of distilled water instead of . Experiment 5 • Repeat Experiment 1 using of distilled water instead of .
Complete Table 2.1, using the information in the descriptions of the experiments and the thermometer diagrams. Calculate the temperature decrease using the equation shown.
On Figure 2.1, write a suitable scale on the y-axis, and plot the results from Experiments 1 to 5. Draw a line of best fit.
State if the energy change in the reaction is exothermic or endothermic. Use the results in Table 2.1 to explain your answer. energy change........................................................................................................................... explanation ................................................................................................................................
Use your graph in Figure 2.1 to predict the temperature decrease if the experiment is repeated using of distilled water. Show your working on Figure 2.1. temperature decrease = ...........................................................
Describe the relationship between the volume of distilled water and the temperature decrease.
Explain why wrapping the boiling tube in cotton wool would improve the accuracy of the results.
Explain why placing the boiling tube in a water-bath at room temperature would not improve the accuracy of the results.
Explain why the volume of distilled water was measured using a measuring cylinder rather than a measuring cylinder.
On Figure 2.1, sketch the graph obtained if all of the experiments were repeated using of solid citric acid and of solid sodium carbonate.
A student tests two substances: solid A and solution B. Tests on solid A Table 3.1 shows the tests and the student’s observations for solid A. Table 3.1 tests | observations test 1: Add of water to a boiling tube containing solid A. Place a stopper in the boiling tube and shake the boiling tube to dissolve solid A and form solution A. Divide solution A into two approximately equal portions. To the first portion of solution A, add aqueous sodium hydroxide dropwise and then in excess. | green precipitate; the precipitate remains test 2: To the product from test 1, add about a depth of aqueous hydrogen peroxide. Test any gas given off. | brown precipitate and effervescence; the gas relights a glowing splint test 3: To the second portion of solution A, add about a depth of dilute nitric acid followed by a few drops of aqueous barium nitrate. | white precipitate
Identify the gas given off in test 2.
Identify solid A.
Tests on solution B Solution B is aqueous aluminium nitrate. The student divides solution B into two approximately equal portions. Record the expected observations. To the first portion of solution B, the student adds aqueous ammonia dropwise until it is in excess. observations .............................................................................................................................
To the second portion of solution B, the student adds aqueous sodium hydroxide dropwise until it is in excess. observations ......................................................................................................................
To the product from 3(d)(i), the student adds a piece of aluminium foil and warms the mixture gently. Any gas given off is tested. observations ......................................................................................................................
Iron nails rust slowly in the presence of water and air. When an iron nail rusts, insoluble solid hydrated iron(III) oxide forms. The solid hydrated iron(III) oxide falls off the iron nail. The rusting of iron nails is slowed down by coating the nails with oil or paint. Plan an investigation to show which of the two coatings, oil or paint, slows down rusting the most. Your plan must include how the results will show which coating slows down rusting the most. You are provided with iron nails, oil, paint, water and common laboratory apparatus.