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    Which volume of oxygen gas, at room temperature and pressure, is required for complete combustion of 1.25 × 103 mol of propan-1-ol?

    A 105 cm3
    B 120 cm3
    C 135 cm3
    D 120 cm3

    Choose one
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    1. Write out the equation for the complete combustion of propan-1-ol
    2. Balance the equation
    3. Determine moles of oxygen using molar ratios
    4. Multiply moles of oxygen by 24000 to determine volume occupied by oxygen
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    Write out the equation for the complete combustion of propan-1-ol. Work out the number of moles of O2 in this combustion using the ratios and the moles you have. Rearrange moles = mass/mr to find mass - 1g = 1cm^3 and therefore you have your answer.
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    (Original post by ReeceM1)
    1. Write out the equation for the complete combustion of propan-1-ol
    2. Balance the equation
    3. Determine moles of oxygen using molar ratios
    4. Multiply moles of oxygen by 24000 to determine volume occupied by oxygen
    Multiply by 24000? Why?
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    (Original post by Kozmo)
    Multiply by 24000? Why?
    1 mol of gas occupies 24 dm^3 at RTP. The answers are given in cm^3, so you multiply by 24000 as there are 1000 cm^3 in a dm^3.

    (Original post by Kozmo)
    Write out the equation for the complete combustion of propan-1-ol. Work out the number of moles of O2 in this combustion using the ratios and the moles you have. Rearrange moles = mass/mr to find mass - 1g = 1cm^3 and therefore you have your answer.
    1g = 1cm^3 for water
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    (Original post by ReeceM1)
    1 mol of gas occupies 24 dm^3 at RTP. The answers are given in cm^3, so you multiply by 24000 as there are 1000 cm^3 in a dm^3.

    1g = 1cm^3 for water
    Ah yes, you're right.
    And in reference to the 1g = 1cm^3, I've seen a mark scheme answer just using volume (1cm^3) in place of mass in this equation. As far as I can recall, it wasn't waster and just used as volume in cm^3 as opposed to mass in grams.
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    Thanks Guys

    I was really stuck on this question (i don't know why) it sounds easy now its explained. Its from the new specification for A-level so they decide to put in multiple choice and all that
 
 
 
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