11.4. The reactions of chlorine
A subsection of Chemistry, 9701, through 11. Group 17
Listing 10 of 290 questions
Identify the substances liberated at the anode and at the cathode during the electrolysis of aqueous sodiumsulfate, Na2SO4. anode cathode  When molten sodiumchloride is electrolysed, chlorine is liberated at the anode and sodium is liberated at the cathode. A sample of molten sodiumchloride is electrolysed for 1.50hours using a current of 4.50 A. Calculate the volume of chlorine and the mass of sodium that are liberated under room conditions.  volume of chlorine = dm3  mass of sodium = g  The equation representing the standard electrode potential, E o, for the reduction of MnO4 –to Mn2+in acid solution is given. MnO4 –+ 8H++ 5e– Mn2++ 4H2OE o = +1.52 V Draw a diagram of the apparatus that would be used to measure the E o value of this half-cell. Your diagram should be fully labelled to identify all apparatus, substances and conditions.  Use the Data Booklet to identify a substance that could be used to oxidise Mn2+ ions to MnO4 – ions under standard conditions. Write an equation for the reaction. 
9701_w20_qp_41
THEORY
2020
Paper 4, Variant 1
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A solution is made by dissolving CuSO4•5H2O in an excess of aqueous ammonia. This solution contains the copper complex [Cu(NH3)4]2+. Write an expression for the Kstab of [Cu(NH3)4]2+. Kstab =  State the colour of the solution of [Cu(NH3)4]2+. The solution of [Cu(NH3)4]2+ is heated gently in a fume cupboard so that NH3 is released. Some NH3 remains in solution and some forms NH3 gas. The colour of the solution changes; a precipitate of Cu(OH)2 forms and is collected. A sample of Cu(OH)2 is added to concentrated hydrochloricacid. A reaction takes place forming a coloured copper complex, Y. A sample of Cu(OH)2 is added to dilute sulfuricacid. A reaction takes place forming a coloured copper complex, Z. [Cu(NH3)4]2+, Y and Z are different colours. Suggest an equation for the reaction of [Cu(NH3)4]2+ to form Cu(OH)2 as the aqueous solution of [Cu(NH3)4]2+ is heated. Suggest an equation for the reaction of Cu(OH)2 with concentrated hydrochloricacid, forming Y. Complete the table with the colour and geometry of complex Y and the colour, geometry and formula of complex Z. Y Z colour of complex geometry of complex formula of complex  Explain why complexes Y and Z are coloured and why their colours are different. 
9701_w20_qp_41
THEORY
2020
Paper 4, Variant 1
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Identify the substances liberated at the anode and at the cathode during the electrolysis of saturated KCl . at the anode at the cathode  When dilute sulfuricacid is electrolysed, oxygen is liberated at the anode. Dilute sulfuricacid is electrolysed for 15.0minutes using a current of 0.750 A. Calculate the volume of oxygen that is liberated under room conditions.  volume of oxygen = cm3 The halogens chlorine, bromine and iodine differ in their strengths as oxidising agents. These strengths are indicated by the E o values for these halogens. Give the E o values for chlorine, bromine and iodine acting as oxidising agents. Deduce which of chlorine, bromine and iodine will react with a solution of Sn2+under standard conditions. Explain your answer. Include a relevant equation in your explanation. An excess of chlorine is added to a solution of acidified Mn2+under standard conditions. Give the formula of the product of this reaction that contains manganese. An electrochemical cell can be made by connecting an Fe3+ / Fe2+ half-cell to an S2O8 2– / SO4 2– half-cell under standard conditions. Calculate the standard cell potential of this electrochemical cell.  = V State the material that should be used as the electrode in each half-cell. in the Fe3+ / Fe2+ half-cell in the S2O8 2– / SO4 2– half-cell  Describe one change to each half‑cell that would increase the value of the cell potential. The temperature should remain at 298 K. Fe3+ / Fe2+ half-cell S2O8 2– / SO4 2– half-cell  
9701_w20_qp_42
THEORY
2020
Paper 4, Variant 2
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Identify the substances liberated at the anode and at the cathode during the electrolysis of aqueous sodiumsulfate, Na2SO4. anode cathode  When molten sodiumchloride is electrolysed, chlorine is liberated at the anode and sodium is liberated at the cathode. A sample of molten sodiumchloride is electrolysed for 1.50hours using a current of 4.50 A. Calculate the volume of chlorine and the mass of sodium that are liberated under room conditions.  volume of chlorine = dm3  mass of sodium = g  The equation representing the standard electrode potential, E o, for the reduction of MnO4 –to Mn2+in acid solution is given. MnO4 –+ 8H++ 5e– Mn2++ 4H2OE o = +1.52 V Draw a diagram of the apparatus that would be used to measure the E o value of this half-cell. Your diagram should be fully labelled to identify all apparatus, substances and conditions.  Use the Data Booklet to identify a substance that could be used to oxidise Mn2+ ions to MnO4 – ions under standard conditions. Write an equation for the reaction. 
9701_w20_qp_43
THEORY
2020
Paper 4, Variant 3
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A solution is made by dissolving CuSO4•5H2O in an excess of aqueous ammonia. This solution contains the copper complex [Cu(NH3)4]2+. Write an expression for the Kstab of [Cu(NH3)4]2+. Kstab =  State the colour of the solution of [Cu(NH3)4]2+. The solution of [Cu(NH3)4]2+ is heated gently in a fume cupboard so that NH3 is released. Some NH3 remains in solution and some forms NH3 gas. The colour of the solution changes; a precipitate of Cu(OH)2 forms and is collected. A sample of Cu(OH)2 is added to concentrated hydrochloricacid. A reaction takes place forming a coloured copper complex, Y. A sample of Cu(OH)2 is added to dilute sulfuricacid. A reaction takes place forming a coloured copper complex, Z. [Cu(NH3)4]2+, Y and Z are different colours. Suggest an equation for the reaction of [Cu(NH3)4]2+ to form Cu(OH)2 as the aqueous solution of [Cu(NH3)4]2+ is heated. Suggest an equation for the reaction of Cu(OH)2 with concentrated hydrochloricacid, forming Y. Complete the table with the colour and geometry of complex Y and the colour, geometry and formula of complex Z. Y Z colour of complex geometry of complex formula of complex  Explain why complexes Y and Z are coloured and why their colours are different. 
9701_w20_qp_43
THEORY
2020
Paper 4, Variant 3
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The reaction scheme shows some reactions of calcium. CaCa(NO3)2CaOCa(OH)2reaction 1 heat CaCO3+ H2Oreaction 2 CO2CaC2reaction 4 Ca(HCO3)2reaction 3 excess CO2CHNO3 NaOHReaction1 produces Ca(NO3)2 and one other product. Identify the other product. Construct an equation for the thermal decomposition of Ca(NO3)2. State the trend in the thermal stability of the Group2 nitrates down the group. In reaction 3, excess CO2 is bubbled through water containing CaCO3. A solution of Ca(HCO3)2forms. Construct an equation for reaction3. Describe how Ca(OH)2 is used in agriculture. In reaction4, calciumcarbide, CaC2, is formed from CaO. CaC2 contains the C2 2– anion. Each carbon in C2 2– is sp hybridised. Describe how sp hybridised orbitals are formed. Sketch a diagram to show how two sp hybrid orbitals can form a sigma (σ) bond.  The flowchart shows some reactions of CaC2. CaC2 CaCN2 NaCN CaCO3 + NH3 reaction 5 NaCl and C N2 H2O Reaction5 can be used to prepare NH3. CaCN2 + 3H2O → CaCO3 + 2NH3 Calculate the minimum mass, in tonnes, of calciumcyanamide, CaCN2, that is required to produce 1.50×106 tonnes of NH3. Show your working. 1 tonne = 1.00 × 106 g  minimum mass of CaCN2 = tonnes  Draw the structure of the organic products formed in the following reactions. CH3CH2Br NaCN dissolved in ethanol H2SO4heat under reflux NaCN and HCN O  
9701_w21_qp_21
THEORY
2021
Paper 2, Variant 1
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The reaction scheme shows some reactions of calcium. CaCa(NO3)2CaOCa(OH)2reaction 1 heat CaCO3+ H2Oreaction 2 CO2CaC2reaction 4 Ca(HCO3)2reaction 3 excess CO2CHNO3 NaOHReaction1 produces Ca(NO3)2 and one other product. Identify the other product. Construct an equation for the thermal decomposition of Ca(NO3)2. State the trend in the thermal stability of the Group2 nitrates down the group. In reaction 3, excess CO2 is bubbled through water containing CaCO3. A solution of Ca(HCO3)2forms. Construct an equation for reaction3. Describe how Ca(OH)2 is used in agriculture. In reaction4, calciumcarbide, CaC2, is formed from CaO. CaC2 contains the C2 2– anion. Each carbon in C2 2– is sp hybridised. Describe how sp hybridised orbitals are formed. Sketch a diagram to show how two sp hybrid orbitals can form a sigma (σ) bond.  The flowchart shows some reactions of CaC2. CaC2 CaCN2 NaCN CaCO3 + NH3 reaction 5 NaCl and C N2 H2O Reaction5 can be used to prepare NH3. CaCN2 + 3H2O → CaCO3 + 2NH3 Calculate the minimum mass, in tonnes, of calciumcyanamide, CaCN2, that is required to produce 1.50×106 tonnes of NH3. Show your working. 1 tonne = 1.00 × 106 g  minimum mass of CaCN2 = tonnes  Draw the structure of the organic products formed in the following reactions. CH3CH2Br NaCN dissolved in ethanol H2SO4heat under reflux NaCN and HCN O  
9701_w21_qp_23
THEORY
2021
Paper 2, Variant 3
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Questions Discovered
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