Find the mass of salt that is formed by the interaction of 100 g of a 9.8% sulfuric acid solution with magnesium.

Given:
m solution (H2SO4) = 100g
ω (H2SO4) = 9.8%
m (MgSO4) -?
Decision:
Let’s compose the reaction equation:
Mg + H2SO4 = MgSO4 + H2 ↑
We calculate the mass of acid in solution:
m (H2SO4) = m solution (H2SO4) * ω (H2SO4) = 100 * 0.098 = 9.8 (g).
Let’s calculate the amount of acid:
n (H2SO4) = m (H2SO4) / M (H2SO4) = 9.8 / 98 = 0.1 (mol).
From the equation follows:
n (H2SO4) = n (MgSO4), so n (MgSO4) = 0.1 (mol).
m (MgSO4) = n (MgSO4) * M (MgSO4), where
M (MgSO4) = 24 32 + 4 * 16 = 120 (g / mol).
m (MgSO4) = 0.1 * 120 = 12 (g).
Answer: the mass of MgSO4 is 12 g.