In the titration of lemon juice, the presence of ascorbic acid means the concentration of citric acid you calculated is higher.
An acid-base titration is a common way to determine the unknown concentration of an acid, given we know the concentration of the base and determine the spent volume in the titration. Let's consider the neutralization reactions that take place in a mixture of citric acid and ascorbic acid.
Citric acid titration :
3 NaOH(aq) + H₃C₆H₅O₇(aq) → Na₃C₆H₅O₇(aq) + 3 H₂O(l)
Ascorbic acid titration:
NaOH(aq) + HC₆H₇O₆(aq) → NaC₆H₇O₆(aq) + H₂O(l)
If we titrated a solution that contained only citric acid, we can relate through stoichiometry the moles and concentration of citric acid. However, if the solution also contained ascorbic acid, we would have to spend more NaOH to titrate it. Since more NaOH would react, we would conclude that there is more citric acid to react, calculating a higher concentration of the same.
In the titration of lemon juice, the presence of ascorbic acid means the concentration of citric acid you calculated is higher.
You can learn more about titration here: brainly.com/question/2728613