0620/62 · Oct/Nov 2024
Download PDFA teacher uses the apparatus shown in Fig. 1.1 to pass an electric current through molten mercury(II) bromide at a temperature of 300°C. During the process shown in Fig. 1.1, the molten mercury(II) bromide breaks down and forms bromine and mercury. Table 1.1 shows some information about mercury(II) bromide, bromine and mercury.
Draw an arrow on Fig. 1.1 to show where the apparatus should be heated.
Name the item of apparatus labelled A in Fig. 1.1.
Name the process shown in Fig. 1.1 which breaks down mercury(II) bromide.
The electrodes used in the process shown in Fig. 1.1 are made from platinum. Give two reasons why platinum is a suitable material for the electrodes.
On Fig. 1.1, draw an X to show where mercury will collect.
Explain why ice is used in the experiment.
A student investigates the rate of the reaction between aqueous iron(III) nitrate and aqueous sodium thiosulfate. The student does five experiments using the apparatus shown in Fig. 2.1. Experiment 1 ● Use a 50cm3 measuring cylinder to pour 50cm3 of aqueous iron(III) nitrate into a 100cm3 beaker. ● Stand the beaker on the text of the printed sheet as shown in Fig. 2.1. ● Use a 25cm3 measuring cylinder to pour 15.0cm3 of aqueous sodium thiosulfate into the beaker. At the same time start a stop-watch. ● Stir the contents of the beaker. ● Look down from above the beaker. When the text on the printed sheet becomes visible, stop the stop-watch and record the time in seconds to the nearest whole number. ● Rinse the beaker with distilled water. Experiment 2 ● Repeat Experiment 1, using 10.0cm3 of aqueous sodium thiosulfate instead of 15.0cm3. Experiment 3 ● Repeat Experiment 1, using 7.0cm3 of aqueous sodium thiosulfate instead of 15.0cm3. Experiment 4 ● Repeat Experiment 1, using 6.0cm3 of aqueous sodium thiosulfate instead of 15.0cm3. Experiment 5 ● Repeat Experiment 1, using 5.0cm3 of aqueous sodium thiosulfate instead of 15.0cm3.
Use the information in the description of the experiments and the stop-watch diagrams to complete Table 2.1.
Write a suitable scale on the y-axis and plot the results from Experiments 1 to 5 on Fig. 2.2. Draw a smooth curve of best fit.
State why the contents of the beaker are stirred after adding the aqueous sodium thiosulfate to the aqueous iron(III) nitrate.
Deduce which experiment has the highest rate of reaction.
Use your graph in Fig. 2.2 to predict the time taken for the text to become visible if the volume of aqueous sodium thiosulfate is 12.5cm3. Show your working on Fig. 2.2.
Explain why it would be an improvement to measure the volumes of aqueous iron(III) nitrate in a burette rather than in a measuring cylinder.
Explain why it is not possible to use a volumetric pipette to measure the volumes of the aqueous sodium thiosulfate used in the experiments.
Describe how the reliability of the results of this investigation can be checked.
Describe how the results of the experiments would change if the experiments are repeated using a narrower and taller beaker. Explain your answer.
Describe additional measurements that must be taken to determine whether the reaction in this investigation is exothermic or endothermic.
A student tests two substances: solid M and solid N. Tests on solid M Table 3.1 shows the tests and the student’s observations for solid M.
Explain why a yellow (safety) Bunsen burner flame is not suitable for a flame test.
Identify the four ions in solid M.
Tests on solid N Solid N is ammonium carbonate. Record the expected observations. The student transfers approximately half of solid N to a boiling tube and adds about 10cm3 of dilute sulfuric acid to the boiling tube. Any gas produced is tested. observations
The student dissolves the remaining solid N in water to form solution N. Solution N is divided into two portions. To the first portion of solution N, the student adds about 2cm3 of aqueous sodium hydroxide and gently warms the mixture. Any gas produced is tested. observations
To the second portion of solution N, the student adds excess aqueous ammonia. observations
Limes and lemons are citrus fruits which contain aqueous citric acid in their juice. Citric acid reacts with alkalis such as aqueous sodium hydroxide. Plan an investigation to find which of lime juice and lemon juice contains the most concentrated aqueous citric acid. Assume that citric acid is the only acid present in the juices. Your plan must include: ● the method to use ● how the results are used to determine which juice contains the most concentrated aqueous citric acid. You are provided with lime juice, lemon juice, aqueous sodium hydroxide and common laboratory apparatus and chemicals.