9701_w21_qp_22 - revisedeck

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Hydrogen iodide, HI, is a colourless gas at room temperature. Explain why HI has a higher boiling point than HCl and HBr. The bar chart shows the boiling points of HCl, HBr and HI. The boiling point of HF is not shown. boiling point / K HF HCl HBr HI Hydrogen bonds form between HF molecules. Draw a bar on the bar chart to predict the boiling point of HF. Explain your answer. The standard enthalpy change of formation, , of HIis +26.5 kJ mol–1. Define the term standard enthalpy change of formation. HIcan be formed by reacting H2with I2. The reaction is reversible, and an equilibrium forms quickly at high temperatures. H2+ I22HIConstruct an expression for the equilibrium constant, Kp, for the reaction of H2and I2to form HI. Kp = The equilibrium partial pressures of the gases at 200 °C are as follows. pH2= 895 Pa pI2= 895 Pa pHI= 4800 Pa Calculate Kp for this reaction. Kp = State how the value of Kp would change, if at all, if the reaction were carried out at 100 °C rather than 200 °C. Explain your answer. HI reacts with oxygen to form iodine and water. Construct an equation for the reaction of HI with oxygen. Explain, with reference to oxidation numbers, why this reaction is a redox reaction. HIcan also be formed by the reaction of I2with hydrazine, N2H4. 2I2+ N2H4→ 4HI+ N2State the change in pressure that would occur when 2 mol I2fully reacts with 1 mol N2H4in a sealed container at constant temperature. Explain your answer. In the laboratory, HIcan be formed in a two-step process. step 1 3I2+ 2P→ 2PI3step 2 PI3+ 3H2O→ H3PO3+ 3HIDraw a ‘dot-and-cross’ diagram of a PI3 molecule. Name the type of reaction in step2. H3PO3and HIare both strong Brønsted–Lowry acids. Give the meaning of the term strong Brønsted–Lowry acid. Give the formula of the conjugate base of H3PO3. HIreacts with propene, CH3CH=CH2to form a mixture of 1-iodopropane and 2-iodopropane. Identify which of 1-iodopropane and 2-iodopropane is the major product of this reaction. Explain your answer. Complete the diagram to show the mechanism of the reaction between HI and CH3CH=CH2 that forms the major product identified in . Include curly arrows, lone pairs of electrons and charges as necessary. C C H H H I H3C H + –

5. Chemical energetics → 5.1. Enthalpy change, \(\Delta H\)

11. Group 17 → 11.2. The chemical properties of the halogen elements and the hydrogen halides

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Table1 gives physical data for some of the Period3 elements. Table 1 atomic number, Z bonding present in element M C first ionisation energy / kJ mol–1 maximum oxidation number +7 anionic radius / nm – – – 0.271 0.212 0.184 0.181 Complete the row in the table labelled ‘bonding present in element’. Use C = covalent, I = ionic, M = metallic, as appropriate. Explain the difference between the first ionisation energies of the elements with atomic numbers 11 and 17. Explain the difference between the first ionisation energies of the elements with atomic numbers 15 and 16. Complete the row in the table labelled ‘maximum oxidation number’. Explain the variation in anionic radius for the elements with atomic numbers 14 to 17. Use the axes to sketch a graph that shows the trend in melting points of the elements with atomic numbers 11 to 17. atomic number, Z melting point of element Dmitri Mendeleev published the first Periodic Table in 1869. Mendeleev used his knowledge of chemical periodicity to propose the properties of gallium, 31Ga, a Group13 element. Table2 gives some chemical and physical data of elements in Group13. Table 2 element density / g cm–3 boiling point / K cationic radius / nm 5B 2.34 0.020 13Al 0.050 31Ga 5.91 49In 7.30 0.081 81Tl 11.8 0.095 Complete the table by predicting values for the missing data. Indium and aluminium are elements in Group13 of the Periodic Table. Indium has very similar chemical properties to aluminium. ● Indium reacts vigorously with hydrochloric acid to form a colourless gas and a salt in solution. ● Indium oxide, In2O3, is amphoteric. ● Gaseous indium bromide has the formula In2Br6. This molecule contains coordinate bonds. Identify the formula of the salt formed when indium reacts with hydrochloricacid. Construct an equation for the reaction of In2O3 with excess aqueous NaOH. Draw a diagram that clearly shows the types of bond present in In2Br6.

9. The Periodic Table: chemical periodicity → 9.2. Periodicity of chemical properties of the elements in Period 3

9. The Periodic Table: chemical periodicity → 9.1. Periodicity of physical properties of the elements in Period 3

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CompoundT is an isomer of C6H12. T Name T. Draw the skeletal formula of a structural isomer of T that shows cis-trans isomerism. Each carbon atom in T forms a sigma (σ) bond to at least one other carbon atom, as shown. C C H3C H3C CH3 CH3 On the diagram, draw the orbitals that represent the pi (π) bond that is also present in T. State the hybridisation of the two carbon atoms between which the pi (π) bond forms. A reaction scheme starting with T is shown. Reaction2 occurs in the presence of a catalyst; knowledge of the mechanism for this reaction is not required. T U reaction 1 reaction 2 catalyst HO OH V O Give the reagentand conditions for reaction1. State and explain how 2,4-dinitrophenylhydrazine (2,4-DNPH) can be used to detect the presence of V as a product of reaction 2. The progress of reaction2 can be monitored by infrared spectroscopy. The absorption caused by O–H bonds is always present because water is used as a solvent. Identify two absorptions, and the bonds responsible for these absorptions, whose appearance will change significantly during the reaction. V is used in a wide range of organic reactions. Some reactions of V are shown. reaction 3 reaction 4 NaBH4 alkaline aqueous I2 reaction 5 reaction 6 dehydration addition polymerisation V X O OH Y Z W O O– V and W are colourless and soluble in water. State what you would observe in reaction3. Reaction3 is a redox reaction. Identify which of the reactants is reduced in this reaction. Construct an equation for reaction4. Use [H] in the equation to represent an atom of hydrogen from NaBH4. C6H12O + �� X is a mixture of two optical isomers. Draw the two optical isomers in the boxes provided. Both optical isomers of X can be dehydrated to form a single product, Y. Give the reagentand conditions required for reaction 5. Y can form an addition polymer Z. Draw one repeat unit of Z. Reaction6 does not proceed quickly at room temperature. Suggest why this is the case.

13. An introduction to AS Level organic chemistry → 13.2. Characteristic organic reactions

14. Hydrocarbons → 14.2. Alkenes

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