Question detail

Calculate the mass of solute in grams needed to prepare 2 dm3 of a 0.5 mol/dm3 potassium nitrate (KNO3) solution. (Mr of KNO3 = 101 g/mol)

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Using concentrations of solutions in mol/dm3 (chemistry only) (HT only)

Question

A. 101 g
B. 202 g
C. 50 g
D. 25 g

Answer

101 g

Explanation

The mass is calculated using the formula mass = moles x Mr. The moles of KNO3 needed are 0.5 mol/dm3 x 2 dm3 = 1 mol. Therefore, mass = 1 mol x 101 g/mol = 101 g.

Common mistake

Incorrect Unit Conversion

Students often forget to convert volumes from cm3 to dm3 when substituting into concentration equations.

Always convert cm3 to dm3 by dividing by 1000 before using the volume in calculations.

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For Concentrations in mol/dm3 and titration calculations, which ratio reasoning answer best supports this Unit 4.3 objective: (chemistry only) (HT only) Substitute numerical values into algebraic equations using appropriate units. (MS 3c)?