How much oxygen is needed to burn 4.8g magnesium?

1. Let’s compose the equation for the reaction of burning magnesium:

2Mg + O2 = 2MgO;

2.Calculate the chemical amount of magnesium:

n (Mg) = m (Mg): M (Mg) = 4.8: 24 = 0.2 mol;

3.the amount of oxygen according to the reaction equation is half the amount of magnesium:

n (O2) = n (Mg): 2 = 0.2: 2 = 0.1 mol;

4.find the volume of oxygen:

V (O2) = n (O2) * Vm = 0.1 * 22.4 = 2.24 dm3.

Answer: 2.24 dm3.