2","label":"a","content":"State the chemical formula of the ion responsible for these acidic properties.","markscheme":"- States $\\text{H}^+$ or $\\text{H}_3\\text{O}^+$ B1","marks":1,"order":0,"markingRubric":null,"explanation":null,"options":[]},{"id":"116b1d35-4873-45fd-8c56-25da1645ff9f","label":"b","content":"A technician prepares a standard solution of sulfuric acid ($\\text{H}_2\\text{SO}_4$) with a concentration of $49.0\\text{ g/dm}^3$. Calculate the mass of $\\text{H}_2\\text{SO}_4$ present in $220\\text{ cm}^3$ of this solution.","markscheme":"- Converts volume to $\\text{dm}^3$: $\\text{Volume} = \\frac{220}{1000} = 0.22\\text{ dm}^3$ M1\n- Calculates mass: $\\text{Mass} = 49.0 \\times 0.22 = 10.78\\text{ g}$ A1","marks":2,"order":1,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"acc4e1b7-a290-4b7c-92c3-50d62addc09c","revisionId":"b1d7642b-cc5e-4aa4-92ca-b56efdd554d5","questionNumber":null,"questionType":"LA","specification":"","difficulty":3,"difficultyBand":"easy","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"83b6a0f4-2163-4e53-bb6a-c7699a0e4d13","label":null,"content":"In a thermite reaction, iron(III) oxide reacts with aluminium to produce molten iron and aluminium oxide. The ratio of the masses of iron(III) oxide and aluminium that react is:\n\n$$\\text{iron(III) oxide} : \\text{aluminium} = 80 : 27$$\n\nCalculate the mass of iron(III) oxide that reacts with $135\\text{ g}$ of aluminium.","markscheme":"- Calculates the scaling factor by dividing the given mass of aluminium by its ratio part: $\\frac{135}{27} = 5$ M1\n- Multiplies the scaling factor by the ratio part of iron(III) oxide to find the reacting mass: $80 \\times 5 = 400\\text{ g}$ A1","marks":2,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"scale_ratio","label":"Scale the mass ratio","steps":[{"type":"text","order":0,"title":"Use the mass ratio","content":"The mass ratio is $$\\text{iron(III) oxide} : \\text{aluminium}=80:27.$$ This means every $27\\text{ g}$ of aluminium reacts with $80\\text{ g}$ of iron(III) oxide.","highlights":[{"text":"\\text{iron(III) oxide} : \\text{aluminium} = 80 : 27","location":"specification"}]},{"type":"text","order":1,"title":"Find the scale factor","content":"Divide the actual aluminium mass by its ratio part:\n\n$$\\frac{135}{27}=5$$\n\nSo the scale factor is $5$. **M1:** this division earns the first mark.","highlights":[{"text":"$$135\\text{ g}$ of aluminium","location":"specification"}]},{"type":"text","order":2,"title":"Scale iron(III) oxide","content":"Multiply the iron(III) oxide ratio part by the same scale factor:\n\n$$80\\times5=400\\text{ g}$$\n\nTherefore, **$400\\text{ g}$ of iron(III) oxide reacts.** **A1:** this correct mass earns the second mark.","highlights":[{"text":"Calculate the mass of iron(III) oxide","location":"specification"}]}]}],"generatedAt":"2026-07-21T05:05:05.494Z","modelVersion":"gpt-5.6-terra","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null}],"subjectCode":"gcse_chemistry__aqa","summaries":[{"id":"03a581b7-0a9a-47a5-94c3-c5358a5506d1","difficultyBand":"medium","calculatorUse":null},{"id":"08637ae2-31ac-4a54-b96b-37d183f8da56","difficultyBand":"medium","calculatorUse":null},{"id":"0a73fb88-17c3-4eb9-85c7-cf6fe17605ee","difficultyBand":"easy","calculatorUse":null},{"id":"124ae350-6845-4711-9541-22b66bac3d8f","difficultyBand":"medium","calculatorUse":null},{"id":"277ec94a-e34c-492f-8d25-584738f4ee14","difficultyBand":"medium","calculatorUse":null},{"id":"293fa975-4405-4ffd-9478-a7079a9f8c30","difficultyBand":"easy","calculatorUse":null},{"id":"2b053164-5f2f-4138-aeb5-40932415a556","difficultyBand":"medium","calculatorUse":null},{"id":"35ffcf5a-e2ff-4f5d-93b1-053910220558","difficultyBand":"easy","calculatorUse":null},{"id":"378391e5-dff2-4ef5-9fe8-e9f7eed59325","difficultyBand":"easy","calculatorUse":null},{"id":"37e0f755-bf98-400b-9f65

Use of amount of substance in relation to masses of pure substances

Question 6

Use of amount of substance in relation to masses of pure substances Questions

Use of amount of substance in relation to masses of pure substances

Question 6

Use of amount of substance in relation to masses of pure substances Questions