CAIE A Level Chemistry 9701 · Atoms, molecules and stoichiometry

Atoms, molecules and stoichiometry: explain question

Explain5 marksChallenge

The Avogadro constant is 6.02 × $10^{23}$ mol $^{-1}$ . Two students are discussing the mole.

Student A: One mole of any substance contains the same number of elementary entities as 12 g of carbon-12, so 1 mol of ethanol and 1 mol of water contain the same number of molecules.

Student B: Since both contain the same number of molecules, 1 mol of ethanol and 1 mol of water must also have the same mass.

Explain whether each student's statement is correct. Use the mole and the Avogadro constant in your answer.

How this question is marked

5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.

Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.

More Atoms, molecules and stoichiometry questions

All Atoms, molecules and stoichiometry questions

Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.