Question detail

Calculate the mass of solute in grams needed to make 2 dm3 of a 0.5 mol/dm3 solution of potassium nitrate (KNO3). (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

To find the mass, use the formula mass = moles x Mr. First, calculate moles: moles = concentration x volume = 0.5 mol/dm3 x 2 dm3 = 1 mol. Then, mass = 1 mol x 101 g/mol = 101 g.

Common mistake

Volume Conversion Mistake

Students often forget to convert cm3 to dm3 when calculating concentration, leading to incorrect results.

Always remember to convert volumes from cm3 to dm3 by dividing by 1000 before using them in concentration 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) Convert volumes between cm3 and dm3 where needed in concentration calculations?