Question

In a titration, 4.7 g of an acid (HX) requires 32.6 mL of 0.54 M NaOH(aq) for complete reaction. What is the molar mass of the acid? Answer in units of g/mol.

Answer 1

Answer : The molar mass of an acid is 266.985 g/mole

Explanation : Given,

Mass of an acid (HX) = 4.7 g

Volume of NaOH = 32.6 ml = 0.0326 L

Molarity of NaOH = 0.54 M = 0.54 mole/L

First we have to calculate the moles of NaOH.

`\text{Moles of }NaOH=\text{Molarity of }NaOH* \text{Volume of solution}=0.54mole/L* 0.0326L=0.017604mole`

Now we have to calculate the moles of an acid.

In the titration, the moles of an acid will be equal to the moles of NaOH.

Moles of an acid = Moles of NaOH = 0.017604 mole

Now we have to calculate the molar mass of and acid.

`\text{Moles of an acid}=\frac{\text{Mass of an acid}}{\text{Molar mass of an acid}}`

Now put all the given values in this formula, we get:

`0.017604mole=\frac{4.7g}{\text{Molar mass of an acid}}`

`\text{Molar mass of an acid}=266.985g/mole`

Therefore, the molar mass of an acid is 266.985 g/mole