During an acid base titration hydrochloride acid is filled in burette up to zero mark and 20 ml of 0.085M Na2CO3 solution is pipette out into flask using indicator: a) if burette reading at end point was noted to be 13.7ml determine molarity of HCl?

1 Answer
Mar 29, 2018

The molar concentration is 0.25 mol/L.

Explanation:

#"Na"_2"CO"_3 +"2HCl" → "2NaCl" + "CO"_2 + "H"_2"O"#

1. Calculate the moles of #"Na"_2"CO"_3#

#"Moles of Na"_2"CO"_3 = "0.020" color(red)(cancel(color(black)("L Na"_2"CO"_3))) ×(0.085 color(white)(l)"mol Na"_2"CO"_3)/(1 color(red)(cancel(color(black)("L Na"_2"CO"_3)))) = "0.001 70 mol Na"_2"CO"_3#

2. Calculate the moles of #"HCl"#

#"Moles of HCl" = "0.001 70"color(red)(cancel(color(black)("mol Na"_2"CO"_3))) × ("2 mol HCl")/(1 color(red)(cancel(color(black)("mol Na"_2"CO"_3)))) = "0.003 40 mol HCl"#

3. Calculate the molar concentration of the #"HCl"#

#c = "moles"/"litres" = ("0.003 40"color(white)(l) "mol")/("0.0137 L") = "0.25 mol/L"#