11. Group 17
A section of Chemistry, 9701
Listing 10 of 617 questions
The compound chlorine dioxide, Cl O2, can be prepared by the reaction shown. NaCl O2 + 1 2Cl 2 Cl O2 + NaCl Using oxidation numbers, explain why this reaction is a redox reaction. The central atom in the molecule of Cl O2 is chlorine. Draw the ‘dot-and-cross’ diagram for Cl O2. Show outer electrons only. The reaction between Cl O2 and F2 is shown. 2Cl O2 + F2 2Cl O2F The rate of the reaction was measured at various concentrations of the two reactants and the following results were obtained. experiment [Cl O2] / mol dm–3 / mol dm–3 initial rate / mol dm–3 s–1 0.010 0.060 2.20 × 10–3 0.025 0.060 to be calculated to be calculated 0.040 7.04 × 10–3 The rate equation is rate = k [Cl O2]. What is meant by the term order of reaction with respect to a particular reagent? Use the results of experiment 1 to calculate the rate constant, k, for this reaction. Include the units of k. rate constant, k = units Use the data in the table to calculate ● the initial rate in experiment 2, initial rate = mol dm–3 s–1 ● [Cl O2] in experiment 3. [Cl O2] = mol dm–3 What is meant by the term rate-determining step? The equation for the reaction between Cl O2 and F2 is shown. 2Cl O2 + F2 2Cl O2F rate = k [Cl O2] The mechanism for this reaction has two steps. Suggest equations for the two steps of this mechanism, stating which of the two steps is the rate-determining step. step 1 step 2 rate-determining step = By considering the rate equation, explain why the rate increases with increasing temperature.
9701_w17_qp_42
THEORY
2017
Paper 4, Variant 2
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PCl 5, PCl 3 and NCl 3 are halides of Group15 elements. PCl 5 can be formed from the reaction of phosphorus with chlorine. PCl 5 has a melting point of 161 °C. Write an equation for the formation of PCl 5 from the reaction of phosphorus and chlorine. State the type of structure and bonding shown by liquid PCl 5. A small amount of PCl 5 is added to excess water. The PCl 5 reacts vigorously to form a colourless solution. Give one other observation you would make when PCl 5 reacts with excess water. Write the equation for the reaction of PCl 5 with excess water. Estimate the pH of the resulting solution. PCl 3 is used to convert alcohols to chloroalkanes, such as compound T. Cl Cl T A possible synthesis of T is shown. Cl Cl HO OH OH HO O reaction 1 using PCl 3 Identify a reagent that could be used in reaction1. T exhibits optical isomerism. Explain what is meant by the term optical isomer and circle any atomin T that give rise to optical isomerism. Cl Cl T  T is a minor product in the reaction of compoundS with excess HCl. S Draw the structure of the major product of the reaction of S with excess HCl.  NCl 3 is a yellow liquid that can be used to bleach flour. Predict the shape of the NCl 3 molecule and the Cl –N–Cl bond angle. shape bond angle  NCl 3 reacts with water to form HOCl, a weak Brønsted-Lowry acid. Explain fully what is meant by the term weak Brønsted-Lowry acid. NCl 3decomposes according to the equation shown. 2NCl 3→ N2+ 3Cl 2A sealed container of volume 250 cm3 contains an unreactive gas at a pressure of 1.00×105Pa. 0.241 g of NCl 3was injected into the sealed container. The sealed container was heated to make the NCl 3decompose fully and then cooled to 20 °C. Calculate the final total pressure inside the sealed container at 20 °C after the NCl 3has fully decomposed.  final total pressure = Pa  
9701_w20_qp_22
THEORY
2020
Paper 2, Variant 2
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Questions Discovered
617