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Mass or moles of a reactant needed to give a volume of gas at STP

This type of question, asked 5 times: 12 May 2024 S2, 13 May 2024 S2, 19 Apr 2025 S2, 17 Apr 2026 S2, 18 Apr 2026 S1. All 5 questions below, oldest first.

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  1. Question 1

    12 May 2024 S2

    72
    What is the mass of KClO3(s)KClO_3(s) required to liberate 22.422.4 dm³ oxygen at STP during thermal decomposition? (Molar Mass of KClO3=122.5KClO_3 = 122.5 g/mol)

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  2. Question 2

    13 May 2024 S2

    91
    According to reaction, Mg(s)+2HCl(aq.)→MgCl2(aq.)+H2(g)↑\text{Mg(s)}+2\text{HCl(aq.)}\to\text{MgCl}_2\text{(aq.)}+\text{H}_2\text{(g)}\uparrow. Calculate the mass of Mg required to liberate 4.48 dm3 H24.48\ \text{dm}^3\ \text{H}_2 at STP? (Molar mass of Mg =24 g mol−1=24\ \text{g mol}^{-1})

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  3. Question 3

    19 Apr 2025 S2

    97
    Find the mass of potassium chlorate required to liberate 5.6dm35.6dm^{3} of oxygen gas at STP? (molar mass of KClO3=122.5 g/molKClO_{3}= 122.5\text{ }g/mol)

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  4. Question 4

    17 Apr 2026 S2

    1
    How many moles of potassium chlorate are heated to produce 11.211.2 L oxygen at STP ?

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  5. Question 5

    18 Apr 2026 S1

    1
    How many moles of potassium chlorate are heated to produce 22.422.4 lit of oxygen at STP ?

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