Question

1L of bleach has a mass of 1,100 grams, 7.25% of the mass of bleach is NaClO, 1 mol of NaClO has a mass of 74.44 grams. What is the molarity (mol/L) of NaClO in the bleach? A.0.097 B.0.93 C. 1.07 D.79.75

Answer 1

Answer:

C. 1.07 M.

Explanation:

Hello,

In this case, we can define the molarity of the bleach as shown below:

$M=\frac{moles_{NaClO}}{V_{solution}}$

In such a way, given the mass of bleach in a 1-L solution, we can compute the density:

$\rho = \frac{1100g}{1L}=1100g/L =1.1 kg/L=1.1g/mL$

In such a way, we can use the previously computed density to compute the volume of the solution, assuming a 100-g solution given the by-mass percent:

$V_{solution}=100g*\frac{1mL}{1.1g} *\frac{1L}{1000mL} =0.091L$

Afterwards, using the by-mass percent of bleach we compute the mass:

$m_{NaClO}=100g*0.0725=7.25g$

And the moles:

$n_{NaClO}=7.25g*\frac{1mol}{74.44g} =0.097mol$

Therefore, the molarity turns out:

$M=\frac{0.097mol}{0.091L}\\ \\M=1.07M$

Thus, answer is C. 1.07 M.

Regards.