[sjt]

Hi Members,

I am not a chemistry expert but whatever I knew, I knew it right way.
My querry is regarding pH conversion to mass of acid.
Lets say pH of acid is 2 and I want to know concentration of HCl in it and mass of HCl matter in it.
My sole objective is to neutralize HCl acid from pH of 2 to say 7, using soda ash.
I want to know how to calculate mass of HCl in pH 2 to neutralize it by simple stiochiometric reaction to get soda ash required to neutralize it.

Initially acid was 15% HCl with pH 0 but later it is pH 2 and I wanna make it pH 7.
Thanks if you need any other information, feel free to reply.

[billnotgatez]

Have you looked at this site
http://www.chembuddy.com/

[Borek]

You can estimate the amount of carbonate needed for neutralization, but it will be always only an approximation. Best approach is to titrate sample using a pH meter to find out the required amount and then to scale up to the total amount of acid.

[aga]

pH is defined as the -log of the concentration of H₃O⁺ cations in solution.

HCl is a strong acid with a pKa of around -7, meaning that it disassociates completely into the ionic species when solvated in water, giving H⁺ (+H₂O => H₃O⁺) and Cl^-.

Measuring the volume of the dilute acid and having an accurate pH value (=titration) you can calculate the moles of acid present in that volume, from which you can calculate the exact amount of base required to neutralise it.

Alternatively you can simply put sodium carbonate (or bicarbonate) into the solution until it stops fizzing, which will give roughly the same result.