Question

About 10ml of concentrated HCl was transferred to a 1-L volumetric flash and diluted to mark with distilled water. When this solution was used to titrate a sample of pure sodium carbonate, Na2Co3, weighing 0.3054 gram, it took 35.09 ml to reach the methyl red end point. The reaction is given by:

2HCl + Na2CO3 --> H2CO3 + 2NaCl

Answer 1

I forgot:

What is the concentration of the solution?

Answer 2

2HCl + Na2CO3 ==> 2NaCl + H2O + CO2
mols Na2CO3 = grams/molar mass = estimated 0.0029
mols HCl = mols Na2CO3 x (2 mol HCl/1 mol Na2CO3) = approx 0.0029 x 2/1 = approx 0.0058 mols HCl
M HCl = mols HCl/L HCl. You know mols HCl and L HCl (0.03509 from the problem), solve for M HCl.

Answer 3

Is molarity also called the concentration of the solution? I got 0.1641 M HCl. Thank you for your help!

Answer 4

There are several units for concentration. One is molarity, but there is also molality, normality, % by mass, % by volume, % by weight/volume and others. Usually titrations are done and the concn is reported in molarity which is mols/L solution.