To determine the molarity of the HCN solution, follow these steps:
1. Convert the volumes from milliliters to liters:
[tex]\[
\text{Volume of HCN solution:} \quad 18.35 \, \text{mL} = \frac{18.35}{1000} \, \text{L} = 0.01835 \, \text{L}
\][/tex]
[tex]\[
\text{Volume of NaOH solution:} \quad 35.4 \, \text{mL} = \frac{35.4}{1000} \, \text{L} = 0.0354 \, \text{L}
\][/tex]
2. Calculate the moles of NaOH used:
[tex]\[
\text{Molarity of NaOH solution:} \quad 0.268 \, \text{M}
\][/tex]
[tex]\[
\text{Moles of NaOH} = \text{Molarity of NaOH} \times \text{Volume of NaOH in liters}
\][/tex]
Substituting the given values:
[tex]\[
\text{Moles of NaOH} = 0.268 \, \text{M} \times 0.0354 \, \text{L} = 0.0094872 \, \text{moles}
\][/tex]
3. Determine the moles of HCN involved in the reaction:
The reaction is:
[tex]\[
\text{HCN} + \text{NaOH} \rightarrow \text{NaCN} + \text{H}_2\text{O}
\][/tex]
From the balanced chemical equation, we can see that the mole ratio of HCN to NaOH is 1:1. Thus, the moles of HCN equals the moles of NaOH:
[tex]\[
\text{Moles of HCN} = 0.0094872 \, \text{moles}
\][/tex]
4. Calculate the molarity of the HCN solution:
[tex]\[
\text{Molarity of HCN} = \frac{\text{Moles of HCN}}{\text{Volume of HCN in liters}}
\][/tex]
Substituting the known values:
[tex]\[
\text{Molarity of HCN} = \frac{0.0094872 \, \text{moles}}{0.01835 \, \text{L}} = 0.517 \, \text{M}
\][/tex]
Therefore, the molarity of the HCN solution is approximately [tex]\( 0.517 \, \text{M} \)[/tex].
