When potassium reacted with water, 8.96 liters of hydrogen were obtained. Find the mass of potassium reacted.

To solve the problem, let’s compose the reaction equation:
2K + 2H2O = 2KOH + H2 – redox reaction, hydrogen is released;
Let’s make calculations using the formulas:
M (K) = 39.1 g / mol;
M (H2) = 2 g / mol;
Determine the number of moles of hydrogen:
1 mol of gas at n. y – 22.4 l;
X mol (H2) -8.96 L hence, X mol (H2) = 1 * 8.96 / 22.4 = 0.4 mol;
Let’s make the proportion:
X mol (K) – 0.4 mol (H2);
-2 mol -1 mol hence, X mol (K) = 2 * 0.4 / 1 = 0.8 mol;
We find the mass of potassium:
m (K) = Y * M – 0.8 * 39.1 = 15.64 g.
Answer: potassium weighing 15.64 g participates in the reaction.