Concentration

% concentration: practice problems

Convert the percentage to grams per litre and to molarity. Every answer here is computed by the same tested calculator the rest of the site uses, so a solution can never drift away from the maths.

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Problem 1 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 0.4
  • Molar mass (optional): 58.44
Show the answer and the working

0.4% w/v = 4 g/L = 0.06845 M.

  1. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = 4 g/L
  2. g/L → M (÷ MW): M = c(g/L) / MW = 0.06845 M

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Problem 2 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 50
  • Basis: % w/w
  • Molar mass (optional): 36.46
  • Density (for w/w): 1.19
Show the answer and the working

50% w/w = 595 g/L = 16.32 M.

  1. %w/w → %w/v (× ρ): %w/v = %w/w · ρ = 59.5% w/v
  2. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = %w/w · 10 · ρ = 595 g/L
  3. g/L → M (÷ MW): M = c(g/L) / MW = 16.32 M

Open this in the calculator to change the numbers.

Problem 3 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 0.2
  • Molar mass (optional): 58.44
Show the answer and the working

0.2% w/v = 2 g/L = 0.03422 M.

  1. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = 2 g/L
  2. g/L → M (÷ MW): M = c(g/L) / MW = 0.03422 M

Open this in the calculator to change the numbers.

Problem 4 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 40
  • Basis: % w/w
  • Molar mass (optional): 36.46
  • Density (for w/w): 1.19
Show the answer and the working

40% w/w = 476 g/L = 13.06 M.

  1. %w/w → %w/v (× ρ): %w/v = %w/w · ρ = 47.6% w/v
  2. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = %w/w · 10 · ρ = 476 g/L
  3. g/L → M (÷ MW): M = c(g/L) / MW = 13.06 M

Open this in the calculator to change the numbers.

Problem 5 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 0.3
  • Molar mass (optional): 58.44
Show the answer and the working

0.3% w/v = 3 g/L = 0.05133 M.

  1. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = 3 g/L
  2. g/L → M (÷ MW): M = c(g/L) / MW = 0.05133 M

Open this in the calculator to change the numbers.

Problem 6 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 0.25
  • Molar mass (optional): 58.44
Show the answer and the working

0.25% w/v = 2.5 g/L = 0.04278 M.

  1. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = 2.5 g/L
  2. g/L → M (÷ MW): M = c(g/L) / MW = 0.04278 M

Open this in the calculator to change the numbers.

Problem 7 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 10
  • Basis: % w/w
  • Molar mass (optional): 36.46
  • Density (for w/w): 1.19
Show the answer and the working

10% w/w = 119 g/L = 3.264 M.

  1. %w/w → %w/v (× ρ): %w/v = %w/w · ρ = 11.9% w/v
  2. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = %w/w · 10 · ρ = 119 g/L
  3. g/L → M (÷ MW): M = c(g/L) / MW = 3.264 M

Open this in the calculator to change the numbers.

Problem 8 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 0.1
  • Molar mass (optional): 58.44
Show the answer and the working

0.1% w/v = 1 g/L = 0.01711 M.

  1. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = 1 g/L
  2. g/L → M (÷ MW): M = c(g/L) / MW = 0.01711 M

Open this in the calculator to change the numbers.

Problem 9 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 30
  • Basis: % w/w
  • Molar mass (optional): 36.46
  • Density (for w/w): 1.19
Show the answer and the working

30% w/w = 357 g/L = 9.792 M.

  1. %w/w → %w/v (× ρ): %w/v = %w/w · ρ = 35.7% w/v
  2. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = %w/w · 10 · ρ = 357 g/L
  3. g/L → M (÷ MW): M = c(g/L) / MW = 9.792 M

Open this in the calculator to change the numbers.

Problem 10 % concentration

Convert the percentage to grams per litre and to molarity.

  • Percent: 15
  • Basis: % w/w
  • Molar mass (optional): 36.46
  • Density (for w/w): 1.19
Show the answer and the working

15% w/w = 178.5 g/L = 4.896 M.

  1. %w/w → %w/v (× ρ): %w/v = %w/w · ρ = 17.85% w/v
  2. %w/v → g/L (× 10): c (g/L) = %w/v · 10 = %w/w · 10 · ρ = 178.5 g/L
  3. g/L → M (÷ MW): M = c(g/L) / MW = 4.896 M

Open this in the calculator to change the numbers.

More concentration practice

Same topic, different calculation

Molar mass, grams and moles

Type an element or formula (Sb, NaCl, C6H12O6) and convert grams to moles. Molar mass is computed from cited atomic weights.

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