Find the mass of butane, which is necessary to obtain butane-1,3-diene weighing 81 g.

Let’s write down the solution, compose the reaction equation:
C4H10 = 2H2 + C4H6 (butadiene – 1.3);
M (C4H10) = 58 g / mol;
M (C4H6) = 54 g / mol;
Determine the number of moles of butadiene – 1.3;
Y (C4H6) = m / M = 81/54 = 1.5 mol;
Let’s make a proportion according to the equation:
X mol (C4H10) – 1.5 mol (C4H6);
-1 mol -1 mol hence, X mol (C4H10) = 1 * 1.5 / 1 = 1.5 mol;
Let’s calculate the mass of butane:
m (C4H10) = Y * M = 1.5 * 58 = 87 g.
Answer: the mass of butane is 87 g.