AS CHEMISTRY Paper 2 Organic and Physical Chemistry

AS CHEMISTRY Paper 2 Organic and Physical Chemistry Tuesday 21 May 2024 Morning Time allowed: 1 hour 30 minutes Materials For this paper you must have: • the Periodic Table/Data Sheet, provided as an insert (enclosed) • a ruler with millimetre measurements • a scientific calculator, which you are expected to use where appropriate. Instructions • Use black ink or black ball-point pen. • Fill in the boxes at the top of this page. • Answer all questions. • You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • All working must be shown. • Do all rough work in this book. Cross through any work you do not want to be marked. Information • The marks for questions are shown in brackets. • The maximum mark for this paper is 80. Advice You are advised to spend about 65 minutes on Section A and 25 minutes on Section B. Section A Answer all questions in this section. box This question is about the analysis of organic compounds. . Table 1 shows the results of chemical tests on three organic compounds. Complete the empty boxes in the table. Table 1 Chemical test Add bromine water orange to colourless no visible change no visible change bubbles of gas no visible change Warm with Fehling’s solution no visible change no visible change [3 marks] . 0.500 g of a hydrocarbon is analysed. The hydrocarbon contains 0.450 g of carbon. Calculate the empirical formula of this hydrocarbon. [3 marks] box Empirical formula Turn over for the next question Turn over ► This question is about infrared spectroscopy. box 0 2 . 1 Compounds A and B both have the molecular formula C4H8O2 Figure 1 shows the infrared spectra of compounds A and B. Use the infrared spectra to deduce a possible structural formula for compound A and a possible structural formula for compound B. [2 marks] Figure 1 Possible structural formula of A Possible structural formula of B 0 2 . 2 Figure 2 shows the infrared spectrum of either pent-1-ene or 2-methylbut-2-ene. Figure 2 Outline how to use the infrared spectrum to determine whether the compound is pent-1-ene or 2-methylbut-2-ene. [2 marks] Question 2 continues on the next page Turn over ► 0 2 . 3 Figure 3 shows the infrared spectrum of methane. Figure 3 Use information from Figure 3 to explain why methane acts as a greenhouse gas. [1 mark] Turn over for the next question DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED box *07* Turn over ► This question is about CFCl3 CFCl3 used to be the propellant in most aerosol cans. box . Use IUPAC rules to name CFCl3 [1 mark] . Give an equation for each of the two propagation steps in the conversion of CHFCl2 into CFCl3 [2 marks] Equation 1 Equation 2 . In the presence of ultraviolet radiation, CFCl3 breaks down in the upper atmosphere to form chlorine free radicals. Give an equation for this reaction. [1 mark] *0* Turn over ► box . Compound J is one of a pair of stereoisomers. Explain: • what stereoisomers are • how E-Z stereoisomerism occurs • how the Cahn-Ingold-Prelog rules can be used to decide whether compound J is an E or Z isomer. box [6 marks] Question 4 continues on the next page Turn over ► 0 4 . 2 Compound J reacts with hydrogen bromide to form compounds K and L. K is the major product. Name and outline the mechanism for the formation of K. [5 marks] Name of mechanism Outline of mechanism . Explain why compound K is the major product in the reaction in Question 04.2. [3 marks] box Turn over for the next question Turn over ► This question is about the volumes of gases involved in some reactions. box . Magnesium reacts with hydrochloric acid. Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) 0.400 g of magnesium is added to 20.0 cm3 of 1.50 mol dm–3 hydrochloric acid. Identify the limiting reagent. Justify your answer. Calculate the volume, in m3, of hydrogen produced at 101 kPa and 15 °C The gas constant, R = 8.31 J K–1 mol–1 [7 marks] Limiting Reagent Justification