How can I determine the concentration of HCl remaining in the flask after back titration?

Question

Thank you!!
I have been given weight of antacid, concentration and volume of HCl and concentration of NaOH. I've done 3 trials and found the average volume of NaOH.

Answer 1

I'm not sure I understand the question. AFTER back titration you have no HCl remaining.
The amount of HCl remaining after the reaction (probably with an antacid tablet) is determined by back titrating the remaining HCl with NaOH. mols NaOH used in the back titration is M x L = ? and that is the same as the mols HCl.
Then initial mols HCl at the beginning of the experiment minus mols HCl remaining (the back titrated part) = mols HCl used in the neutralization of the tablet.

Answer 2

Sorry if I confused you. I miss-wrote my question.

My question was: How can I determine the concentration of HCl remaining in the flask.

I calculated the # of moles of HCl neutralized by the tablet which was around 0.014 M.
I don't understand the steps needed to calculate the concentration of HCl remaining in the flask.
Given:
Con. of HCl: 0.14M
Volume added:100mL
Con. of NaOH:0.145M
Weight of Tablet: 1.3g