9701_s23_qp_22
A paper of Chemistry, 9701
Questions:
5
Year:
2023
Paper:
2
Variant:
2
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1
The melting points of some solids are shown in Table 1.1. Table 1.1 solid melting point / K magnesium phosphorus sodium chloride sulfur State the type of bonding present in magnesium and in sodium chloride. bonding in magnesium bonding in sodium chloride Explain the difference in the melting points of magnesium and sodium chloride. Explain the difference in the melting points of phosphorus and sulfur in terms of structure and bonding. Define electronegativity. Explain why electronegativity increases across a period. Name the strongest intermolecular force that exists between NH3molecules. Draw a diagram to show the formation of the strongest intermolecular force between two molecules of NH3. Include any relevant lone pairs of electrons and dipoles. The melting points of ice and ammonia are shown in Table 1.2. Table 1.2 solid melting point / K ice ammonia Suggest two reasons for the difference in the melting points of ice and ammonia.
3. Chemical bonding  →  3.6. Intermolecular forces, electronegativity and bond properties
4. States of matter  →  4.2. Bonding and structure
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Chlorine is a reactive element. It forms many compounds. Complete Table 2.1 to show the maximum oxidation number of the elements Na to P in their chlorides. Table 2.1 element Na Mg Al Si P maximum oxidation number State what determines the maximum oxidation number of elements in Period 3. An excess of cold water is added to the chloride of silicon. Write an equation for the reaction between an excess of cold water and the chloride of silicon. Suggest the pH of the solution produced in . An excess of cold water is added to the chloride of phosphorus. Write an equation for the reaction between an excess of cold water and the chloride of phosphorus. Suggest the pH of the solution produced in . Write an equation for the reaction of chlorine with water. Write an equation for the reaction of chlorine with hot NaOH. Bleach is used as a cleaning product to kill bacteria. It is made by adding compounds like sodium chlorate(, NaCl O, to water. Identify the formula of the ion present in bleach that kills bacteria. Sodium chlorate(, NaCl O, reacts with hydrogen peroxide to produce sodium chloride, water and oxygen gas. Construct an equation for this reaction. A sample of bleach W contains an unknown concentration of sodium chlorate(. 10.0 cm3 of W is diluted with distilled water to make a total volume of 100 cm3 of bleach solution. 25.0 cm3 of this diluted bleach solution is added to an excess of hydrogen peroxide and the volume of gas produced measured under room conditions. The experiment is repeated and on average 25.0 cm3 of diluted bleach solution produces 42.0 cm3 of gas. Calculate the concentration, in g dm–3, of sodium chlorate(in W. concentration of NaCl O in W = g dm–3
11. Group 17  →  11.4. The reactions of chlorine
9. The Periodic Table: chemical periodicity  →  9.2. Periodicity of chemical properties of the elements in Period 3
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describes a sequence of reactions that can be used to produce a food additive, compound Y, from CH3CH2Cl . CH3CH2Cl CH3CH2CN CH3CH2COOH step 1 X Y step 2 dilute acid step 3 CaState the reagent and conditions for step 1 in . Give the systematic name of X. Identify the type of reaction that occurs when dilute acid is added to X in step 2. In step 3, Y and a gas are produced. Construct an equation for step 3. CH3CH2COOH can also be formed from propan-1-ol and potassium dichromate(. State the conditions required. Complete Table 3.1 to show the number of sigma bonds (σ ) and pi bonds (π) present in a molecule of X. Table 3.1 type of bond number of bonds in X sigma (σ ) pi (π)
21. Organic synthesis  →  21.1. Organic synthesis
11. Group 17  →  11.4. The reactions of chlorine
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In industry, ethanol is made by reacting ethene with steam in the presence of H3PO4. reaction 1 C2H4+ H2OC2H5OHUse the bond energy values in Table 4.1 to calculate the enthalpy change, ΔHr , for reaction 1. Table 4.1 bond bond energy / kJ mol–1 C–C C=C C≡C C–H C–O C=O O–H ΔHr = kJ mol–1 Reaction 1 reaches equilibrium at constant temperature and pressure. Deduce what effect increasing the pressure will have on the amount of ethanol in the new equilibrium mixture. Use Le Chatelier’s principle to explain your answer. effect of increasing pressure explanation The mechanism for reaction 1 can be described in three steps. Steps 1 and 2 for reaction 1 are shown in . step 1 step 2 H2C H HO OH O CH2 H H2C H P O HO OH O– P O C+ H H2C H H H H C+ H H3C CH2 O+ H H O Describe the behaviour of H3PO4 in step 1 in . Explain your answer. Identify the species that behaves as an electrophile in step 2 in . Explain your answer. Complete to show the mechanism for step 3 of reaction 1. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. H HO OH O P O HO OH O– P O H3C CH2 O+ H H3C CH2 O H H Describe how a catalyst affects a reaction. Explain your answer. Use and to justify why H3PO4 is described as a catalyst in reaction 1. Propene also reacts with steam. A mixture of organic products is produced. Explain why propan-2-ol is produced in the higher yield. Describe the covalent bonds present between the carbon atoms in an ethene molecule by completing Table 4.2. Table 4.2 sigma (σ ) pi (π) type of orbitals involved in bond how the orbitals overlap
14. Hydrocarbons  →  14.2. Alkenes
7. Equilibria  →  7.1. Chemical equilibria: reversible reactions, dynamic equilibrium
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Describe structural isomerism. A and B are structural isomers with molecular formula C5H10O. They are both straight-chained molecules with only one functional group. Table 5.1 describes observations when separate samples of A and B are added to different reagents. Table 5.1 reagent A B 2,4-dinitrophenylhydrazine (2,4-DNPH reagent) orange precipitate appears orange precipitate appears Tollens’ reagent silver mirror appears no reaction alkaline I2no reaction no reaction Name the functional group present in both A and B. Draw the structures of A and B in the boxes. A B C is a structural isomer of A and B. C is straight chained and has two functional groups. C shows only one type of stereoisomerism. Table 5.2 describes observations when separate samples of C are added to different reagents. Table 5.2 reagent C 2,4-dinitrophenylhydrazine (2,4-DNPH reagent) no reaction Br2orange to colourless alkaline I2yellow precipitate appears Draw the structure of C in the box. C Name the type of stereoisomerism shown by molecules of C. D reacts in the presence of a sulfuric acid catalyst to form E and water. The structure of E is shown in . O E O Name the functional group present in E. Identify the type of reaction that occurs when D reacts to form E. Draw the structure of D in the box. D The infrared spectrum of E is shown in . transmittance / % wavenumber / cm–1 Table 5.3 bond functional groups 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 2850–2950 N–H amine, amide 3300–3500 O–H carboxyl hydroxy 2500–3000 3200–3600 Use and Table 5.3 to predict two differences in the absorptions above 1500 cm–1 of the infrared spectrum of D compared to E. Explain your answer.
17. Carbonyl compounds  →  17.1. Aldehydes and ketones
13. An introduction to AS Level organic chemistry  →  13.1. Formulas, functional groups and the naming of organic compounds
15. Halogen compounds  →  15.1. Halogenoalkanes
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