We have two solutions with known volume and pH. We want to mix them together and then adjust its pH to a specific value using 1M HCl which also has a known pH. Without any trial we want to exactly know the required volume of HCl for pH adjustment. Theoretically we can find the total concentration of H+ in the mixture that shows its pH. But will it be exactly the pH which would be obtained if measured? Actually I want to know that if the theoretical pH and actual one are equal to each other.
Do you mean that you want to prepare buffer solution or you are doing acid-base reaction or you are mixing salts.But any way the most accurate way is to use pH meter
Depending on the actual model you want to use you can estimate the pH of a solution of known compounds (strong/weak acids/bases). But consider following things:
1. pH is NOT the TOTAL concentration of H+ but the FREE concentration. Weak acid will "catch" all protons from stronger acids and so on. You can calculate this concentration if you know the strength of your acids/bases.
2. pH is a thermodynamic parameter. Technically, it depends on the activity not only on the concentration and with that also on temperature, pressure, solved gas concentrations in your water and so on. So, the calculated pH will either over- or underestimate the real value.
If you just have the pH value of the solutions (not WHAT is in it) than it will be hard to make any guesses.
Do you mean that you want to prepare buffer solution or you are doing acid-base reaction or you are mixing salts.But any way the most accurate way is to use pH meter
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