Question

Find the Total Alkalinty and Bicarbonate content from these numbers:

I pipetted a 25.0mL aliquot of our unknown into a flask, then titrated with standarized HCl which was 0.1011M. We reached a end point and found the total volume dispensed was 5.39mL.

I then pipetted a 25.00ml aliquot of the unknown and added 50.00mL of 0.1010M NaOH to it. We titrated the excess NaOH with my standarized 0.1011M HCl solution to the endpoint. I dispensed 50.17mL of HCl to reach an endpoint.

Please show all work. Will thumbs up!

Answer 1

We know that formula for total alkalinity is T.VxMx100x1000 / V ppm as CaCO₃.

Here,

T.V = volume of HCl rundown to reach the endpoint ( i.e, buratte reading)

M=Molarity of HCl used for the titration

100 =Molecular weight of CaCO₃

V= volume of the sample taken.

Case -1:-

Volume of unknown sample taken = 25ml

M=Molarity of HCl = 0.1011M

Titer volume T.V = 5.39 ml

Total alkalinity = 5.39x0.1011x100x1000 / 25

= 54492.9 / 25

= 2179.7 ppm as CaCO3

Case-2:-

Volume of the unknown sample taken = 25 ml

Molarity of HCl = 0.1011 M

Titer volume T.V = 50.17 ml

Total alkalinity = 50.17x0.1011x 100x 1000 / 25

= 507218.7 / 25

= 20288.75 ppm as CaCO3