Question

Ordinary bleach is $5.25\% $ $NaOCl$ by mass with density of $1.11g/mL$. How many grams of $NaOCl$ are in $50mL$ of bleach?
A.) $5.82g$
B.) $2.91g$
C.) $275g$
D.) $11.5g$

Answer 1

Hint: In this question, first we will calculate the mass of the solution of bleach from the given mass and volume of bleach and then the mass of sodium hypochlorite ($NaOCl$) is $5.25\% $ of the mass of ordinary bleach.

Complete step by step answer:
As we know that the compound $NaOCl$ has a general chemical name as Sodium hypochlorite. Also, the ordinary household bleach consists of a dilute solution of sodium hypochlorite ($NaOCl$) and other secondary ingredients.
As we know that the density of a substance can be given as the division of mass to that of volume. Therefore, the formula of density can be written as:
${\text{Density}} = \dfrac{{{\text{Mass}}}}{{{\text{Volume}}}}$ $ - (1)$
In the question, we are given that the density of ordinary bleach solution is $1.11g/mL$ and the volume of the bleach solution is $50mL$. Hence, form the equation $ - (1)$ the mass of bleach solution can be written as:
Mass of bleach solution $ = 1.11 \times 50$
                                            $ = 55.5g$
Also, it is given in question that ordinary bleach is $5.25\% $ $NaOCl$ by mass which means that
the mass of sodium hypochlorite ($NaOCl$) is $5.25\% $ of the mass of ordinary bleach. Therefore,
 Mass of sodium hypochlorite ($NaOCl$) $ = \dfrac{{5.25}}{{100}} \times 55.5$
                                                                       $ = 2.91g$
As the mass of sodium hypochlorite ($NaOCl$) is $2.91g$.

Hence, option B.) is the correct answer.

Additional information:
 The ordinary bleach is used in industries and also for domestic works for the purpose of removing color from a fabric or also to clean or to remove stains from the fabric. This process is also called a bleaching process. As ordinary bleach is a dilute solution of sodium hypochlorite solution, therefore it is also known as liquid bleach.

Note:
Remember that the ordinary bleach is made from the mixture of chlorine, caustic soda (which is also known as sodium hydroxide), and water by the process of electrolysis through a sodium chloride salt solution.