In what type of household product would you expect to find sodium hypochlorite? A solution of sodium hypochlorite, NaOCl, is labelled as having a concentration of 5% (w/v) - Leaving Cert Chemistry - Question 11(a) - 2002

The 5% (w/v) solution signifies that there are 5 grams of sodium hypochlorite in 100 cm³ of solution. To convert this to grams per litre:

egin{align*} 5 ext{ g/100 cm}^3 &= rac{5 ext{ g}}{100 ext{ cm}^3} imes 1000 ext{ cm}^3
&= 50 ext{ g/L}. \end{align*}

Based on the balanced reaction:

egin{align*} ext{Number of moles of OCl}^- &= 0.067 ext{ mol}
ext{From the reaction, } 1 ext{ mol of OCl}^- ext{ produces } 1 ext{ mol of Cl}_2
ext{Thus, } 0.067 ext{ mol of OCl}^- ext{ will produce } 0.067 ext{ mol of Cl}_2. \end{align*}

To find the number of molecules, use Avogadro's number:

egin{align*} ext{Number of molecules} &= 0.067 ext{ mol} imes 6 imes 10^{23}
&= 4 imes 10^{22} ext{ molecules.}
\end{align*}

Using the standard molar volume at s.t.p. ( ext{approximately } 22.4 ext{ L/mol}), the volume occupied by 0.067 mol of chlorine gas is calculated as follows:

egin{align*} ext{Volume} &= 0.067 ext{ mol} imes 22.4 ext{ L/mol}
&= 1.5 ext{ L}.
\end{align*}