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1:35 (Triple only) understand how to carry out calculations involving gas volumes and the molar volume of a gas (24dm³ and 24,000cm³ at room temperature and pressure (rtp))

The molar volume of a gas is the volume that one mole of any gas will occupy.

1 mole of gas, at room temperature and pressure (rtp), will always occupy 24 dm³ or 24,000 cm³.

Note: 1 dm³ = 1000 cm³

The following formulae allows for the interconversion between a volume in dm³ or cm³ and a number of moles for a given gas:

Amount(mol) = \frac{volume(dm^3)}{24}

Amount(mol) = \frac{volume(cm^3)}{24000}

Example 1:

Calculate the amount, in moles, of 12 dm³ of carbon dioxide (CO₂).

Amount = \frac{volume(dm^3)}{24}

Amount = \frac{12}{24}

Amount = 0.5mol

Example 2:

Calculate the volume at rtp in cubic centimetres (cm³), of 3 mol of oxygen, (O₂).

Volume = amount \times 24000

Volume = 3 \times 24000

Volume = 72000cm^3

Spec	Q'stion	Ans	MS
1:35	Jan '12 (2), Q 5 c ii	Answer	MkS
1:35	Jan '13 (2), Q 7 a i	Answer	MkS
1:35	Jan '13 (2), Q 7 a ii	Answer	MkS
1:35	Jan '13 (2), Q 7 a iii	Answer	MkS
1:35	Jan '13 (2), Q 7 a iv	Answer	MkS
1:35C	Jan '15 (2), Q 7 c	Answer	MkS
1:35C	Jan '16 (2), Q 5 c ii	Answer	MkS
1:35C	Jan '17 (2), Q 7 a ii	Answer	MkS
1:35C	Jan '18 (2), Q 5 c i	Answer	MkS
1:35	May '10 (2), Q 7 e	Answer	MkS
1:35	May '11 (2), Q 7 a i	Answer	MkS
1:35	May '11 (2), Q 7 b i	Answer	MkS
1:35	May '11 (2), Q 7 b ii	Answer	MkS
1:35	May '12 (2), Q 5 b i	Answer	MkS
1:35	May '13 (2), Q 6 c	Answer	MkS
1:35	May '13 (2), Q 7 c i	Answer	MkS
1:35	May '13 (2R), Q 5 d ii	Answer	MkS
1:35C	May '14 (2), Q 7 c iii	Answer	MkS
1:35C	May '14 (2R), Q 6 b i	Answer	MkS
1:35C	May '16 (1R), Q 10 a ii	Answer	MkS
1:35C	May '16 (2), Q 8 b	Answer	MkS
1:35C	May '16 (2R), Q 6 b ii	Answer	MkS

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Q'stion

Ans

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