In 300 ml of water was dissolved 40 g of sulfuric acid. Find the mass fraction of sulfuric acid in the resulting solution.

Given: m (water) = 300 ml, m (acid) = 40 g.
Find: ω (acid) -?
Decision.
1. Calculate the mass of water by the formula m = ρ • V, where ρ = 1 g / ml:
m (water) = ρ (water) • V (water) = 1 g / ml • 300 ml = 300 g. For water, the volume is equal to the mass, so this action is not necessary.
2. Calculate the mass of the solution:
m (solution) = m (acid) + m (water) = 40 g + 300 g = 340 g.
2. Calculate the mass fraction of the solute (acid):
ω (acid) = m (acid) / m (solution) = 40 g: 340 g = 0.1176, or,
multiplying this value by 100%, we get 11.76%.
Answer: ω (acids) = 11.76%.

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