Question

A 4.00 g mass of NaOH is dissolved in 5.00 mL of water. A 4.00-mL aliquot of this solution is then diluted to exactly 500 mL of solution using distilled water. What is molar concentration of NaOH in the final diluted solution?

Answer 1

Answer: The molar concentration of NaOH in the final diluted solution is 0.056 M

Step-by-step explanation:

To calculate the molarity of solution, we use the equation:

`\text{Molarity of the solution}=\frac{\text{Mass of solute}* 1000}{\text{Molar mass of solute}* \text{Volume of solution (in mL)}}`

Given mass of NaOH = 4.00 g

Molar mass of NaOH = 40 g/mol

Volume of solution = 5.00 mL

Putting values in above equation, we get:

`\text{Molarity of NaOH solution}=(1.40* 1000)/(40* 5)\\\\\text{Molarity of NaOH}=7M`

To calculate the molarity of the diluted solution, we use the equation:

`M_1V_1=M_2V_2`

where,

`M_1\text{ and }V_1` are the molarity and volume of the concentrated NaOH solution

`M_2\text{ and }V_2` are the molarity and volume of diluted NaOH solution

We are given:

`M_1=7M\\V_1=4.00mL\\M_2=?M\\V_2=500mL`

Putting values in above equation, we get:

`7* 4.00=M_2* 500\\\\M_2=(7* 4.00)/(500)=0.056M`

Hence, the molar concentration of NaOH in the final diluted solution is 0.056 M