0620_w24_qp_42
A paper of Chemistry, 0620
Questions:
6
Year:
2024
Paper:
4
Variant:
2
Login to start this paper & get access to powerful tools
1
The formulae of the molecules A to I are shown in Table 1.1. Table 1.1 molecule formula A C2H4 B C2H5OH C CO D CO2 E Cl 2 F NO2 G N2 H O2 I SO2 Answer the following questions about the molecules, A to I. Each letter may be used once, more than once or not at all. State which of the molecules A to I: is an element with a triple bond is a product of photosynthesis is used as a fuel turns limewater milky undergoes a substitution reaction with alkanes is a colourless liquid at r.t.p. is unsaturated is 21% of clean, dry air is a reactant in the Haber process.
11. Organic chemistry  →  11.4. Alkanes
11. Organic chemistry  →  11.2. Naming organic compounds
11. Organic chemistry  →  11.5. Alkenes
Open
2
Aluminium is manufactured by the electrolysis of aluminium oxide. State the name of the main ore of aluminium. Name the substance mixed with aluminium oxide to reduce the operating temperature of the process. Explain why the molten mixture in conducts electricity. Table 2.1 contains some information about the processes which take place at the anode and the cathode. Table 2.1 anode cathode 2O2– → O2 + e– ……………………………………. Complete Table 2.1: ● Write the number of electrons needed to balance the ionic half-equation for the reaction at the anode. ● Write the ionic half-equation for the reaction at the cathode. State why the process at the anode is an oxidation. Oxygen is formed at the anode. Explain why the main gas given off at the anode is carbon dioxide and not oxygen. State why aluminium is used in food containers. Aluminium reacts with fluorine to form the ionic compound aluminium fluoride. Complete the dot-and-cross diagram in of the ions in aluminium fluoride. Give the charges on the ions. Al F F F
9. Metals  →  9.6. Extraction of metals
4. Electrochemistry  →  4.1. Electrolysis
Open
3
Sulfur forms two chlorides, P and Q. Chloride P has the formula S2Cl 2. Chloride Q has the formula SCl 2. Both chlorides are covalently bonded and have low melting points. Suggest, in terms of attraction between particles, why these chlorides have low melting points. Chloride P, S2Cl 2, forms when sulfur reacts with chlorine. Write the symbol equation for this reaction. Complete the dot-and-cross diagram in of a molecule of chloride Q, SCl 2. Show outer electrons only. Cl S Cl Chloride P is converted to chloride Q by reaction with chlorine in a closed system. The reversible reaction reaches an equilibrium. S2Cl 2+ Cl 22SCl 2P Q The forward reaction is exothermic. Suggest two changes to the conditions which will result in a decrease in the concentration of chloride Q at equilibrium. The rate of the forward reaction in is determined by collision theory. The rate of reaction depends upon two factors: ● the frequency of collisions between particles ● the proportion of collisions which have energy greater than or equal to the activation energy. Define the term activation energy. Give the symbol for activation energy. Complete Table 3.1 to show the effect, if any, when the conditions are changed. Use only the words increases, decreases or no change. Table 3.1 change to conditions effect on the frequency of collisions between particles effect on the proportion of collisions which have energy greater than or equal to the activation energy concentration of chlorine is increased temperature is increased a catalyst is added The reaction of chloride P with chlorine is a redox reaction. S2Cl 2+ Cl 22SCl 2P Q The oxidation number of Cl in chloride P and chloride Q is –1. Use oxidation numbers to explain why: ● sulfur is oxidised in the forward reaction ● chlorine is oxidised in the reverse reaction.
6. Chemical reactions  →  6.2. Rate of reaction
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
Open
4
Silver bromide, AgBr, is made when aqueous silver ethanoate, CH3COOAg, is added to aqueous sodium bromide, NaBr. The equation for the reaction is shown in equation 1. equation 1 CH3COOAg + NaBr → CH3COONa + AgBr The method includes the following steps. step 1 Add 200.0 cm3 of 0.0500 mol / dm3 CH3COOAg to a beaker. This volume contains 0.0100 mol of Ag+ ions. step 2 Add 50.0 cm3 of aqueous NaBr. This volume contains 0.0100 mol of Br – ions. A precipitate forms. step 3 Filter the mixture. step 4 Dry the solid residue until all the water is removed. step 5 Record the mass of the dry residue. Complete the ionic equation for the reaction by adding the missing state symbols. Ag+( ) + Br –( ) → AgBr( ) Name a different aqueous silver salt which could be used in step 1. Use the information in step 2 to calculate the concentration of aqueous NaBr. concentration = mol / dm3 State the colour of the precipitate which forms in step 2. Use the information in step 1, step 2 and equation 1 to determine the number of moles of AgBr formed. Use this value to calculate the mass of AgBr formed. number of moles of AgBr = mass of AgBr = g Name the salt dissolved in the filtrate in step 3. The recorded mass of the dry residue in step 5 is greater than the mass calculated in because a step is missing from the procedure. Suggest the missing step. Name the substance responsible for the greater mass of the dry residue. Barium sulfate can be made by the same method but with different aqueous solutions. Suggest two aqueous solutions which can be added together to make barium sulfate. and Write the balanced symbol equation for this reaction.
7. Acids, bases and salts  →  7.3. Preparation of salts
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
Open
5
Alkenes are manufactured by cracking larger alkane molecules. State the source of the large alkane molecules used in cracking. State two conditions needed for cracking large alkane molecules. When one molecule of dodecane, C12H26, is cracked, three molecules of but-1-ene and one other product are formed. Use molecular formulae to complete the symbol equation for this reaction. C12H26 → + Suggest the type of chemical reaction which happens during cracking. Propene will undergo polymerisation. Suggest the name of the polymer formed from propene. Draw part of this polymer molecule to show three repeat units. State the type of polymerisation propene undergoes.
11. Organic chemistry  →  11.5. Alkenes
Open
6
Polyamides and polyesters are polymers. Polyamides can occur naturally or can be manufactured. Part of the structure of a polyamide is shown in . C O C O C C O O N H N H N H N H C O On , draw a circle around one amide linkage. Complete to show the structures of the two monomers needed to make the polymer in . Show all of the atoms and all of the bonds in the functional groups. Name the other product formed in this polymerisation. State the term given to natural polyamides. Name the type of monomers which are used to make natural polyamides. One of the monomers which forms part of a natural polyamide has three carbon atoms. Complete to show the displayed formula of this monomer. C H PET is a polyester. Name the two types of monomer molecules needed to make polyesters. and Draw part of the structure of PET which shows two repeat units. Show all of the atoms and all of the bonds in the linkages.
11. Organic chemistry  →  11.8. Polymers
Open