Question

Watch the animation in the first hint. Then answer the following questions about the below reaction: Ca(OH)2​(aq)+2HCl(aq)--> CaCl2​(aq)+H2​O(l) An aqueous solution of Ca(OH)2with a concentration of 0.167 M was used to titrate 25.00 mL of aqueous HCl. 11.43 mL of the Ca(OH)2was required to reach the endpoint of the titration. How many moles of base were required to react completely with the acid in this reaction? ____mol Ca(OH)2 How many moles of HCl were present in the original 25.00 mL of acid? ____mol HCl

Answer 1

molarity of Ca(OH)2 = 0.167M

volume of Ca(OH)2 = 11.43mL

Volume of HCl = 25.0 mL

1) At the equivalence

Ca(OH)2 + 2HCl -----------> CaCl2 + 2H2O

V1M1/n1 = V2M2/n2

11.43 x0.167 /1 = 25 xM2 /2

thus molarity of HCl solution = 0.1527 M

a) number of moles of base required to react completely with acid = V1M1/n1

= 11.43 x 0.167

= 1.9088 mmoles

= 1.9088x10^-3 moles of base

b) the molarity of acid = 0.1527 M

That is

in 1000mL of solution 0.1527 moles of Hcl are present

then in 25 mL the moles of HCl present = 25mL x 0.1527 moles / 1000mL

=0.003817 moles of HCl