Question

The amount of hydrogen required to reduce 30 g of 2-butene is _______ g (rounded off to 2 decimals).

Hint:

Hydrogenation of one C=C bond consumes 1 mol of H$_2$ per mole of alkene.

Answer 1

Correct Answer: 1.05

Step 1: Reaction.
\[ \text{C}_4\text{H}_8 + \text{H}_2 \rightarrow \text{C}_4\text{H}_{10} \] 1 mol of 2-butene reacts with 1 mol of H$_2$.
Step 2: Moles of 2-butene.
Molecular weight = 56 g/mol
\[ \text{Moles} = \frac{30}{56} = 0.5357~\text{mol} \] Step 3: Moles and mass of H$_2$.
Moles of H$_2$ = 0.5357 mol
\[ \text{Mass of H}_2 = 0.5357 \times 2.016 = 1.08~\text{g} \] (Recheck with precise molar mass) \[ \Rightarrow 0.5357 \times 2 = 1.07~\text{g} \] Rounded off → 1.07 g