Calculate the mass of the precipitate obtained by reacting 12 g of MgSO4 with a NaOH solution.

Given:
m (MgSO4) = 12 g
To find:
m (Mg (OH) 2) =?
Decision:
1) Let’s compose the equation of the chemical reaction, let the mass of the sediment be x g.
MgSO4 + 2NaOH = Mg (OH) 2 + Na2SO4
2) Find the molecular weights of magnesium sulfate and magnesium hydroxide.
M (MgSO4) = 24 + 32 + 64 = 120 g / mol
M (Mg (OH) 2) = 24 + 2 + 32 = 58 g / mol
3) 12 g: 120 g / mol = x g: 58 g / mol
x = (12 x 58): 120 = 5.8 g.
Answer: m (Mg (OH) 2) = 5.8 g.