A student measures out exactly 100 cm3 of a copper(II) sulfate solution whose concentration is 0.5 mol/dm3. Using moles equals concentration multiplied by volume in dm3, how many moles of copper(II) sulfate are present?

A student measures out exactly 100 cm3 of a... | Chemistry 0620 | Paper 2 Mock 01 | Multiple Choice (Extended)

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A student measures out exactly 100 cm³ of a copper(II) sulfate solution whose concentration is 0.5 mol/dm³. Using moles equals concentration multiplied by volume in dm³, how many moles of copper(II) sulfate are present?

0.005 mol

5 mol

0.5 mol

0.05 mol

Answer Details

The amount present is 0.05 mol. Convert the volume first: 100 cm³ ÷ 1000 = 0.100 dm³. Then n = c × V = 0.5 × 0.100 = 0.05 mol of CuSO₄.

Choosing 0.5 mol simply repeats the concentration, which is the amount in a full dm³, not in a tenth of one. Choosing 5 mol multiplies by the volume in cm³ without converting, or shifts the decimal the wrong way. Choosing 0.005 mol divides by 1000 twice. The rule is that concentration is moles per dm³, so the volume in the formula must always be in dm³.

Read lesson note on The Mole And The Avogadro Constant (CIE)

Read lesson note on Use Of Amount Of Substance In Relation To Masses Of Pure Substances (OxfordAQA)

Read lesson note on Chemical Combination (JAMB)

Read lesson note on The Mole Concept (OxfordAQA)

Read lesson note on Stoichiometry And Chemical Reactions (WAEC)

The Mole And The Avogadro Constant

Use Of Amount Of Substance In Relation To Masses Of Pure Substances

Chemical Combination

The Mole Concept

Stoichiometry And Chemical Reactions

Molar Concentrations

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