Find the masses of salt and water required to prepare 100 g of a 5% solution.

m (solution) = 100g
w (%) = 5%
Find: m (salt | pure substance) – ?, m (H2O) -?
1) w (%) = [m (in-va) / m (solution)] * 100%
Based on this formula, we express the mass of the pure substance (mass of salt) in the solution:
m (salt) = [m (solution) * w (%)] / 100%
m (salt) = [100 g * 5%] / 100%
m (salt) = 5g
We found a mass of salt, that is, a mass of pure substance in solution
2) Find the mass of water m (H2O). To do this, subtract m (in-va) from m (solution):
m (H2O) = m (solution) -m (in-va)
m (H2O) = 100g – 5g = 95g.
m (H2O) = 95g.
Answer: m (salt) = 5g, m (H2O) = 95g.

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