Question

Household bleach contains about \(5.2 \mathrm{~g}\) of sodium hypochlorite in \(100 \mathrm{~g}\) (two significant figures) of water. What is the molarity of sodium hypochlorite in bleach? (Assume no volume change.)

Short answer

Answer: The molarity of sodium hypochlorite in the bleach solution is approximately 0.698 M.

Step-by-step solution

Convert the mass of sodium hypochlorite into moles.

To convert the mass into moles, we need the molar mass of sodium hypochlorite (NaClO). The molar mass of Na is 22.99 g/mol, Cl is 35.45 g/mol, and O is 16.00 g/mol. So, the molar mass of NaClO is 22.99 + 35.45 + 16.00 = 74.44 g/mol. Now, we can use this to convert the mass of sodium hypochlorite into moles: \[\frac{5.2 \mathrm{~g}}{74.44 \mathrm{~g/mol}} = 0.0698 \mathrm{~mol}\]

Calculate the volume of the solution in liters.

The volume of the solution is given as 100 g of water. To convert this mass to volume, we need to use the density of water, which is approximately \(1 \mathrm{~g/mL}\). So, 100 g of water is equal to 100 mL, which is equal to 0.1 L. (Note: The problem states to assume no volume change, so we can assume that the total volume of the solution is 0.1 L.)

Use the moles and volume to determine the molarity.

Finally, to calculate the molarity, we use the formula: \[Molarity = \frac{moles}{volume} = \frac{0.0698 \mathrm{~mol}}{0.1 \mathrm{~L}} = 0.698 \mathrm{M}\] So, the molarity of sodium hypochlorite in bleach is approximately 0.698 M.