Posted by natash on .
If 20.0mL of .2019M HCI requires 39.63mL of a NaOH solution for complete neutralization, what is the concentration of the NaOH solution? how many significant figures are justified in the answer?

chemacid base titrations 
DrBob222,
HCl + NaOH ==> NaCl + H2O
mols HCl used = L x M = 0.0200 L x 0.2019 M = ??
mols NaOH (from the equation it is a 1:1 ratio of HCl to NaOH; therefore, mols NaOH must be the same as that for HCl).
mols NaOH = L x M
You have L (0.03963 mL) and you have mols (from HCl), calculate M NaOH. You can have as many s.f. as the least number in your calculations; therefore, you may have 3 since 20.0 mL has three.