Find the mass of salt formed by the reaction between 20 g of magnesium oxide and 63 g of nitric acid.

1. Let’s write the equation of interaction of magnesium oxide with nitric acid:

MgO + 2HNO3 = Mg (NO3) 2 + H2O;

2. find the chemical amount of magnesium oxide:

n (MgO) = m (MgO): M (MgO);

M (MgO) = 24 + 16 = 40 g / mol;

n (MgO) = 20: 40 = 0.5 mol;

3.Calculate the amount of nitric acid:

n (HNO3) = m (HNO3): M (HNO3);

M (HNO3) = 1 + 14 + 3 * 16 = 63 g / mol;

n (HNO3) = 63: 63 = 1 mol;

4.determine the amount of magnesium nitrate formed:

n (Mg (NO3) 2) = n (MgO) = 0.5 mol;

5. calculate the mass of salt:

m (Mg (NO3) 2) = n (Mg (NO3) 2) * M (Mg (NO3) 2);

M (Mg (NO3) 2) = 24 + 28 + 6 * 16 = 148 g / mol;

m (Mg (NO3) 2) = 0.5 * 148 = 74 g.

Answer: 74 g.