1,4-dibromobutane weighing 108 g was heated with excess zinc dust.

1,4-dibromobutane weighing 108 g was heated with excess zinc dust. Find the volume of hydrogen required to hydrogenate the resulting cyclobutane.

Given:
m (C4H8Br2) = 108 g

To find:
V (H2) -?

Decision:
1) Write the equation of reactions:
C4H8Br2 + Zn => C4H8 + ZnBr2;
C4H8 + H2 => C4H10;
2) Calculate the molar mass of C4H8Br2:
M (C4H8Br2) = Mr (C4H8Br2) = Ar (C) * N (C) + Ar (H) * N (H) + Ar (Br) * N (Br) = 12 * 4 + 1 * 8 + 80 * 2 = 216 g / mol;
3) Calculate the amount of substance C4H8Br2:
n (C4H8Br2) = m (C4H8Br2) / M (C4H8Br2) = 108/216 = 0.5 mol;
4) Determine the amount of substance H2:
n (H2) = n (C4H8) = n (C4H8Br2) = 0.5 mol;
5) V (H2) = n (H2) * Vm = 0.5 * 22.4 = 11.2 liters.

Answer: The volume of H2 is 11.2 liters.