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The structure of lycopene is shown. To separate the lycopene, the filtered juice was shaken in a separating funnel with heptane, C7H16, and the mixture was left to form two immiscible layers, which were run into separate flasks. Predict which layer will…
Before the samples were measured, an absorption spectrum was recorded to find the best wavelength to use. (i) Describe the contents of the two solutions required to record the spectrum: the reference solution and the blank. (ii) The spectrum obtained is shown.…
The ascorbic acid in the juice was determined by titration with a standard solution of iodine, I2. The method is based on the following redox reaction: C6H8O6(aq) + I2(aq) → C6H6O6(aq) + 2 I−(aq) + 2 H+(aq) (i) Deduce the oxidizing agent in this…
The students wished to compare their result for ascorbic acid with the value given for pink grapefruit juice in a food-composition database. Suggest two aspects of the data or of the samples that the students must check before judging whether their value…
(i) Sulfur dioxide is oxidized to sulfur trioxide by nitrogen dioxide in the atmosphere. Determine the enthalpy change, ΔH⊖, in kJ mol−1, for the reaction SO2(g) + NO2(g) → SO3(g) + NO(g) given these reactions and enthalpy…
The oxidation of sulfur dioxide to sulfur trioxide is an equilibrium reaction. 2 SO2(g) + O2(g) ⇌ 2 SO3(g) (i) State the equilibrium constant expression, K, for the reaction. (ii) Explain, with a reason, how compressing the gas mixture at constant…
Nitrogen monoxide reacts with chlorine in the atmosphere: 2 NO(g) + Cl2(g) → 2 NOCl(g) The rate equation was determined experimentally as Rate = k[NO]2[Cl2]. (i) A student proposed the following mechanism and suggested that Step 1 was the…
What is the correct electron configuration of the selenium atom? A. 1s22s22p63s23p63d104s24p4 B. 1s22s22p62d103s23p64s24p4 C. 1s22s22p63s23p63d104s24p6 D. 1s22s22p63s23p63d84s24p6
(i) Determine the enthalpy of combustion of pentane, in kJ mol−1, using table 12 in the data booklet. C5H12(g) + 8 O2(g) → 5 CO2(g) + 6 H2O(g) (ii) Calculate the mass, in g, of carbon dioxide, CO2, produced when 45.0 g of pentane react with…
Pentane reacts with bromine, Br2, to form 2-bromopentane. (i) Explain, using equations, the initiation step and two propagation steps for this reaction. (ii) 2-Bromopentane reacts with aqueous sodium hydroxide, NaOH(aq), to form pentan-2-ol,…