Using the reaction equation Mg (OH) = MgO + H2O, calculate the mass of magnesium hydroxide

Using the reaction equation Mg (OH) = MgO + H2O, calculate the mass of magnesium hydroxide if magnesium oxide is formed 30 g.

Given:
m (MgO) = 30 g

To find:
m (Mg (OH) 2) -?

1) Mg (OH) 2 => MgO + H2O;
2) M (MgO) = Mr (MgO) = Ar (Mg) * N (Mg) + Ar (O) * N (O) = 24 * 1 + 16 * 1 = 40 g / mol;
3) n (MgO) = m / M = 30/40 = 0.75 mol;
4) n (Mg (OH) 2) = n (MgO) = 0.75 mol;
5) M (Mg (OH) 2) = Mr (Mg (OH) 2) = Ar (Mg) * N (Mg) + Ar (O) * N (O) + Ar (H) * N (H) = 24 * 1 + 16 * 2 + 1 * 2 = 58 g / mol;
6) m (Mg (OH) 2) = n * M = 0.75 * 58 = 43.5 g.

Answer: The mass of Mg (OH) 2 is 43.5 g.