Transcript text: Consider the reaction
\[
\mathrm{Mg}(\mathrm{~s})+\mathrm{HCl}(\mathrm{ag}) \rightarrow \mathrm{MgCl}_{2}(\mathrm{ag})+\mathrm{H}_{2}(\mathrm{~g})
\]
a) Balance the reaction
\[
1 M_{2(s)}+2 H C l_{(4)} \rightarrow 1 M_{g} C l_{2(y)}+1 \mathrm{H}_{2(g)}
\]
b) A reaction contains 2.50 g of solid magnesium is mixed with 2.50 mL of 0.100 M HCl. Determine the limiting reagent, and the excess reagent.
\[
\begin{array}{l}
\begin{array}{r}
2.50 \mathrm{~mL} \mathrm{HCl} \times \frac{1 \mathrm{~L} \mathrm{HCl}}{1000 \mathrm{mLHCl}}=0.0025 \mathrm{~L} \rightarrow 0.100 \mathrm{M}=\frac{\text { mlec HCl }}{0.0025}=0.00025 \mathrm{molHCl} \times \frac{1 \mathrm{md} \mathrm{MyCl}}{2 \mathrm{md} \mathrm{HCl}}= \\
0.000125 \mathrm{~mol}
\end{array} \\
0.000125 \mathrm{~mol} \mathrm{mgl}_{2} \mathrm{HCl} \text { is L.R } \\
\text { c) How many grams of } \mathrm{MgCl}_{2} \text { can be produced from the above reaction based on the }
\end{array}
\]
\[
0.000125 \mathrm{molM} \mathrm{M}_{2} \mathrm{Cl}_{2} \times \frac{95.2112 \mathrm{M}_{2} \mathrm{Cl}_{2}}{1 \mathrm{mal} \mathrm{M}_{2} \mathrm{Cl}_{2}}=0.0119 \mathrm{M}_{2} \mathrm{M}_{2} \mathrm{Cl}_{2}
\]
d) How many grams of hydrogen gas will be evolved from the reaction based on the limiting reagent?
\[
0.000125 \mathrm{md} \mathrm{MeCl} 2 \times \frac{1 \mathrm{~mol} \mathrm{H2}}{1 \mathrm{~mol} \mathrm{MgCl}} \times \frac{2.016 \mathrm{~g} \mathrm{H}_{2}}{1 \mathrm{molH}}=0.000252 \mathrm{~g}
\]
\[
\begin{array}{l}
\text { e) How many grams of the excess reagent left unreacted? } \\
0.100 \mathrm{M}=\frac{\text { moles of } \mathrm{HCl}}{0.00250 \mathrm{~L}}=\text { moles of } \mathrm{HCl}=2.5 \times 10^{-4} \text { moles } \\
2.5 \times 10^{-4} \mathrm{~mol} \mathrm{HCl} \times \frac{36.461, \mathrm{HCl}}{1 \mathrm{~mol}}=9.12 \times 10^{-3} \mathrm{~g} \mathrm{HCl} \\
\end{array}
\]