Calculate the mass and amount of the calcium oxide substance formed during the combustion of 25 g of calcium

Let’s compose the equation of the calcium combustion reaction:
2Ca + O2 = 2CaO;

The molecular weight of calcium is 40 g / mol. Let’s find the amount of substance in calcium:
25/40 = 0.625 mol;

Let’s find the molecular weight of calcium oxide:
40 + 16 = 56 g / mol;

Calcium oxide has the same coefficient as before calcium. This means that the amount of substance in calcium oxide is 0.625 mol. Find the mass of calcium oxide:
0.625 * 56 = 35 grams;

Answer: the mass of calcium oxide is 35 grams, the amount of substance in calcium oxide is 0.625 mol.