A 0.2722 g sample of a pure carbonate, X n CO 3 ( s ) , was dissolved in 50.0 mL of 0.1200 M HCl ( aq ) . The excess HCl ( aq ) was back titrated with 23.60 mL of 0.0980 M NaOH ( aq ) . How many moles of HCl react with the carbonate?

0.00369 moles of HCl react with carbonate.

Explanation:

Number of moles of HCl present initially = moles = 0.00600 moles

Neutralization reaction (back titration):

According to above equation, 1 mol of NaOH reacts with 1 mol of 1 mol of HCl.

So, excess number of moles of HCl present = number of NaOH added for back titration = moles = 0.00231 moles

So, mole of HCl reacts with carbonate = (Number of moles of HCl present initially) - (excess number of moles of HCl present) = (0.00600 - 0.00231) moles = 0.00369 moles

Hence, 0.00369 moles of HCl react with carbonate.

i'm pretty sure its b i might be wrong though!