How many grams of propyl alcohol is needed to produce 0.5 liters of hydrogen when interacting with Na?

Given:
V (H2) = 0.5 l

To find:
m (C3H7OH) -?

Decision:
1) Write the reaction equation:
2C3H7OH + 2Na => 2C3H7ONa + H2 ↑;
2) Calculate the amount of substance H2:
n (H2) = V (H2) / Vm = 0.5 / 22.4 = 0.02 mol;
3) Determine the amount of C3H7OH substance:
n (C3H7OH) = n (H2) = 0.02 * 2 = 0.04 mol;
4) Calculate the molar mass of C3H7OH:
M (C3H7OH) = Mr (C3H7OH) = Ar (C) * N (C) + Ar (H) * N (H) + Ar (O) * N (O) = 12 * 3 + 1 * 8 + 16 * 1 = 60 g / mol;
5) Calculate the mass of C3H7OH:
m (C3H7OH) = n (C3H7OH) * M (C3H7OH) = 0.04 * 60 = 2.4 g.

Answer: The mass of C3H7OH is 2.4 g.