Question

What mass of solid NaOH (97.0 % by mass) is required to prepare 1.00 L of a 10.0% solution of NaOH by mass? The density of the 10.0% solution is 1.109 g/ml.

Answer 1

Answer: The mass of 97 % of NaOH solution required is 114.33 g

Explanation:

To calculate mass of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

We are given:

Density of 10 % solution = 1.109 g/mL

Volume of 10% solution = 1 L = 1000 mL     (Conversion factor:  1 L = 1000 mL)

Putting values in above equation, we get:

$1.109g/mL=\frac{\text{Mass of }10\%\text{ solution}}{1000mL}\\\\\text{Mass of }10\%\text{ solution}=1109g$

The mass of 10 % solution is 1109 g.

To calculate the mass of concentrated solution, we use the equation:

$c_1m_1=c_2m_2$

where,

$c_1\text{ and }m_1$ are the concentration and mass of concentrated solution.

$c_2\text{ and }m_2$ are the concentration and mass of diluted solution.

We are given:

$c_1=97\%\\m_1=?g\\c_2=10\%\\m_2=1109g$

Putting values in above equation, we get:

$97\times m_1=10\times 1109\\\\m_1=114.33g$

Hence, the mass of 97 % of NaOH solution required is 114.33 g