Question

Consider the titration of H ₃C ₆H ₅O ₇ with NaOH. You need to add 0.0207 moles of NaOH in order for the indicator dye to change color. How many moles of H ₃C ₆H ₅O ₇ must you have had to start? (report answer to the correct sig figs)

Answer 1

Answer:

0.0069 moles

Calculation:

We know that indicator dye changes color when the acid is completely neutralized by addition of base.

In this case acid is Citric acid and bas is NaOH.

As Citric acid is a triprotic acid, 3 mols of NaOH is required in order to neutralize 1 mol of Citric acid.

3 mols of NaOH neutralizes 1 mol of Citric acid.

1 mol of NaOH will neutralize 1÷3 mol of Citric acid.

0.0207 mol of NaOH will neutralize 0.0207÷3=0.0069 mol of Citric acid.

So, 0.0069 moles of Citric acid was initially present.