Determine the mass of flint that is needed to react with oxygen 20g.

Let’s implement the solution:

According to the condition of the problem, we compose the equation of the process:
2Si + 2O2 = 2SiO2 – compounds, silicon oxide was obtained;

Calculations according to the formulas of substances:
M (Si) = 28 g / mol;

M (O2) = 32 g / mol.

Determine the amount of O2:
Y (O2) = m / M = 20/32 = 0.625 mol.

Y (Si) = 0.625 mol since the amount of substances is equal to 2 mol.

We find the mass of the original substance:
m (Si) = Y * M = 0.625 * 28 = 17.5 g

Answer: you need silicon weighing 17.5 g