Calculating the volume of a certain number of moles
4 marks · NormalAnswer the following questions about the volume of gases at rtp.
What is meant by the term 'molar volume'?
State the molar volume at room temperature and pressure in dm³ and in cm³.
A student says the molar volume of oxygen is different from that of carbon dioxide at rtp. Explain whether this statement is correct.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) The volume occupied by 1 mole of a gas at room temperature and pressure. · must show Reference to 1 mole, Reference to rtp
(b) 24 dm³ and 24,000 cm³ · must show States both dm³ and cm³
(c) The statement is incorrect. At rtp, 1 mole of any gas occupies the same volume because 1 mole contains the same number of molecules. · must show States it's incorrect, Explains same number of molecules per mole
Common mistakes: Stating molar volume is different for different gases at same conditions; Incorrect units
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Defines molar volume as the volume occupied by 1 mole of any gas at rtp.
B2 (b) · 1 mark · Correctly states 24 dm³ and 24,000 cm³.
B3 (c) · 1 mark · States the statement is incorrect (or equivalent).
B4 (c) · 1 mark · Explains 1 mole of any gas at rtp has the same number of molecules, so the volume is the same.
Worked solution
a) Molar volume is the volume that 1 mole of gas occupies at room temperature and pressure (rtp).
b) 24 dm³ and 24,000 cm³
c) The statement is incorrect. At rtp, 1 mole of any gas occupies the same volume because 1 mole has the same number of molecules.