AQA GCSE COMBINED SCIENCE: TRILOGY H Higher Tier Chemistry Paper 2H 2023

In a chromatography experiment, a blue colour moved 4.77 cm. The solvent moved 5.30 cm. Calculate the Rf value for the blue colour. Black ink is a mixture of several colours. Plan an experiment using paper chromatography to: • separate the colours in black ink Crude oil is a mixture of many different compounds. 0 3 . 1 Give two reasons why crude oil is not a formulation. Describe how crude oil is separated into fractions. The fractions from crude oil contain alkanes. Explain why alkanes are cracked. Cracking produces a mixture of products. 0 3 . 4 An equation for cracking decane (C10H22) is: C10H22(l) → C10H20(l) + H2(g) Describe a test to identify the gas produced in the reaction. Alkenes are produced in cracking. The general formula for the homologous series of alkenes is CnH2n Which formula represents an alkene? Some types of water contain dissolved substances. A student investigated the mass of dissolved solids in distilled water and in sea water. Figure 1 shows the apparatus. This is the method used. 1. Weigh an evaporating basin. 2. Add 20 cm3 of distilled water to the evaporating basin. 3. Weigh the evaporating basin and the water sample. 4. Heat the water sample for 2 minutes. 5. Weigh the evaporating basin and contents. 6. Repeat steps 1 to 5 two more times. 7. Repeat steps 1 to 6 with sea water. The method used by the student did not give valid results. Describe one improvement the student could make to obtain valid results. The student concludes that distilled water is pure. Describe a test to confirm that distilled water is pure.