9701_w22_qp_22 - revisedeck

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Species such as NH4 +, CO3 2– and PO4 3– are examples of molecular ions. Ionic and covalent bonds both involve an electrostatic attraction between different species. Identify the species that are electrostatically attracted to one another in: ● an ionic bond ● a covalent bond. Complete Table1.1 to show the total numbers of protons and electrons in the molecular ions NH4 +, CO3 2– and PO4 3–. Table 1.1 molecular ion total number of protons total number of electrons NH4 + CO3 2– PO4 3– NH4 + is a Brønsted–Lowry acid. Define Brønsted–Lowry acid. When NH4 +is heated with NaOH, a pungent gas is produced. Write an ionic equation for this reaction. The nitrogen atom in NH4 + is sp3 hybridised. sp3 orbitals form from the mixing of one 2s and three 2p orbitals. Sketch the shapes of a 2s and a 2px orbital on the axes in Fig.1.1. 2s z x y 2px z x y There are many naturally occurring hydrated compounds that contain the anion PO4 3–. Name the anion PO4 3–. Struvite is a soft hydrated mineral with Mr = 245.3. The anhydrous form of the mineral has the formula NH4MgPO4. Calculate the number of molecules of water of crystallisation in struvite. Give your answer to the nearest integer. Show your working. number of molecules of water of crystallisation = OH–reacts with 2-bromo-2-methylpropane in an SN1 reaction. The molecular ion (CH3)3C+ forms as the intermediate in this reaction. Draw the mechanism for the SN1 reaction of OH– with 2-bromo-2-methylpropane. Include charges, dipoles, lone pairs of electrons and curly arrows as appropriate. Draw the structures of the organic reactant and organic product. H3C CH3 CH3 + C 2-bromo-2-methylpropane is a tertiary bromoalkane. Define tertiary bromoalkane. Organic compound M forms when 2‑bromo‑2‑methylpropane is heated with ethanolic OH–. Draw the structure of M.

2. Atoms, molecules and stoichiometry → 2.3. Formulas

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

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The chlorides of some of the Period3 elements are shown in Table2.1. Table 2.1 Period 3 chloride NaCl Al Cl 3 SiCl 4 PCl 5 PCl 3 SCl 2 bonding C C structure S S oxidation state of Period 3 element Complete Table 2.1. ● Identify the bonding shown by each chloride under standard conditions. Use C = covalent, I = ionic, M = metallic. ● Identify the structure shown by each chloride under standard conditions. Use G = giant, S = simple. ● Deduce the oxidation state of the Period 3 element in each chloride. Write equations for the reactions of NaCl and PCl 5 with water. Include state symbols in both equations. NaCl PCl 5 In the gas phase, Al Cl 3exists at equilibrium with Al 2Cl 6as shown. equation 1 2Al Cl 3Al 2Cl 6∆Hr = –63 kJ mol–1 Complete the dot-and-cross diagram to show the bonding in Al 2Cl 6. Al Cl Cl State the effect of an increase in temperature on the equilibrium mixture in equation1. Explain your answer. A 3.30 g sample of a Period3 chloride is heated to 500 K in a sealed flask. At this temperature, the chloride is a gas of volume 250 cm3 and the pressure in the flask is 323 kPa. Use the ideal gas equation pV = nRT to calculate the Mr of the Period3 chloride. Deduce its formula. Mr = formula of Period 3 chloride = An excess of Cl –is added to 1 cm3 of Br2. Describe what is observed. Explain your answer. SCl 2 has Mr = 103.1 and is a liquid at room temperature. SBr2 has Mr = 191.9 and is a gas at room temperature. Explain the difference in the physical state of SCl 2 and SBr2. Give your answer in terms of intermolecular forces. Bismuth is a dense metal in the same group as phosphorus. Draw a labelled diagram to show the bonding in bismuth metal. Bismuth reacts with chlorine to form BiCl 3. BiCl 3 is a solid at room temperature. It melts when heated gently. BiCl 3 reacts vigorously with water at room temperature to form an acidic solution. Suggest the type of bonding and structure shown by BiCl 3. Explain your answer.

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

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Organic compounds can be distinguished using chemical tests and analytical techniques. Table3.1 shows four pairs of organic compounds. Table 3.1 organic compounds reagent positive result of chemical test on identified compound A1 O H O A2 O B1 O B2 O C1 O O C2 D1 D2 OH CH3 OH Complete Table3.1 to: ● identify a reagent which can distinguish between the compounds in each pair ● give the positive result of the chemical test and identify which compound shows this result. Use a different reagent for each test. A1 and A2 are structural isomers. Define structural isomers. Give the systematic name of B2. Deduce the molecular formula of D1. D2 forms polymerZ when heated gently. Identify the type of polymer that forms from D2. Draw one repeat unit of polymerZ. Organic compoundE contains three carbon atoms. E reacts with cold dilute acidified KMnO4to form a single compoundF with Mr = 154.9. Fig.3.1 shows the infrared spectrum of E. Fig.3.2 shows the infrared spectrum of F. E transmittance / % wavenumber / cm–1 F transmittance / % wavenumber / cm–1 Table 3.2 bond functional group containing the bond characteristic infrared absorption range (in wavenumbers) / cm–1 C–O hydroxy, ester 1040–1300 C=C aromatic compound, alkene 1500–1680 C=O amide carbonyl, carboxyl ester 1640–1690 1670–1740 1710–1750 C≡N nitrile 2200–2250 C–H alkane 2850–3100 N–H amine, amide 3300–3500 O–H carboxyl hydroxy 2500–3000 3200–3650 Both spectra show absorptions between 2850 and 2950 cm–1 owing to C–H bonds in each molecule. Use the two infrared spectra and Table 3.2 to identify the functional group present only in E. Explain your answer, referring only to absorptions at frequencies greater than 1500 cm–1. functional group explanation Use the infrared spectrum of F to identify the functional group formed when E reacts with cold dilute acidified KMnO4. Explain your answer, referring only to absorptions at frequencies greater than 1500 cm–1. functional group explanation The mass spectrum of E shows a molecular ion peak and an M+2 peak of approximately equal abundance at m/e = 120 and 122. Deduce the relative molecular mass, Mr, of E. Mr = Use the information in 3to suggest a structure for E. Complete the equation for the reaction of E with cold dilute acidified KMnO4to form F. In the equation, [O] represents cold dilute acidified KMnO4. H2O + [O] + → C2 can be synthesised using A1 as a single organic reactant. A1 O H O O C2 Devise a multi-step synthetic route to form C2 from A1. Identify relevant reagents and conditions, and state the organic products of each step.

13. An introduction to AS Level organic chemistry → 13.1. Formulas, functional groups and the naming of organic compounds

22. Analytical techniques → 22.1. Infrared spectroscopy

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