What V oxygen is required to react with 4 grams of calcium?

Given:

m (Ca) = 4 g.

To find:

V (O2) =?

Decision:

1) Let’s compose the equation of the chemical reaction:

2Ca + O2 = CaO.

2) The formula for solving the problem: V: Vm = m: M, hence V = (Vm x m): M.

3) Find the molecular weight of calcium.

M (Ca) = 40 g / mol.

4) Vm is a constant value and is equal to 22.4 l / mol.

5) V (O2) = (22.4 x 4): 40 = 2.24 l.

Answer: V (O2) = 2.24 liters.