Question

1.0 g of magnesium is burnt with 0.56 g o2 in a closed vessel. Which reactant is left in excess and how much? (at. Wt. Mg = 24; o = 16) choose answer: mg, 0.16 g o2, 0.16 g mg, 0.44 g o2, 0.28 g

Answer 1

Answer:

Mg, 0.16g O2

Explanation:

The reaction is as follows

M_{g}+\frac{1}{2}O_{2}\rightarrow M_{g}O

modes of M_{g}=\frac{1}{24}=0.04167

modes of O_{2}=\frac{0.56}{32}=0.0175

According to reaction stoichiometry \frac{1}{24 } modes of M_{g} require \frac{1}{48} modes of O_{2} or 0.02083 modes of O_{2}

clearly O_{2} is the limiting reagent modes of M_{g} required by 0.01175 modes of O_{2}=0.0175\times 2=0.035ml

\therefore Excess M_{g}=0.04167-0.035

=0.00667ml

=0.16 g