10 g of magnesium oxide was treated with a solution containing 40 g of nitric acid. How much salt is formed?

1) First, we write down the reaction equation:

MgO + 2HNO3 = Mg (NO3) 2 + H20

2) We write down the known masses of substances:

m (MgO) = 10 (g)

m (HNO3) = 40 (g)

3) Now we find out the number of moles of substances participating in the reaction:

v (MgO) = 10 (g) / 40 (g / mol) = 0.25 mol

v (HNO3) = 40 (g) / 63 (g / mol) x 2 = 1.27 mol

4) Nitric acid is in excess, which means we will calculate the mass of salt by magnesium oxide:

M (Mg (NO3) 2) = 24 + (14 + 48) x 2 = 148 (g / mol)

m (Mg (NO3) 2) = 0.25 (mol) х 148 (g / mol) = 37 (g)

Answer: the mass of salt is 37 grams