Question

How do you determine the pH of citric acid?

Answer 1

Hint: The pH of a substance is the value of the hydrogen ion concentration in an aqueous solution which can be changed with dilution. Citric acid is the substance which is made up of solid crystalline structures and it has to be dissolved for measuring the pH.

Complete answer:
 In the question it is asked how we will determine the pH of citric acid. From the time we are studying about the acids and bases we classify many acids as strong acids and weak acids and the bases as weak bases and strong bases. We know that the substance which donates $H^{+}$ ions on dissociation in aqueous solution is called as the acids and those which gives $O{H}^{-}$ ions is called as the bases or be said as those accepts the $H^{+}$ ions.
We differentiate between bases and acids samples provided to us by determining its pH value.
Now we should know what is a pH value?
pH denotes “power of hydrogen” or the “potential of hydrogen” and the pH values is determined with the value of $H^{+}$ ions present in the solution. pH value gives an idea that the taken sample is acid or basic. pH value is the negative logarithm value of $H^{+}$ concentration of the sample. The pH scale ranges from 0-14. If pH value is from 0-7, then the sample will be acidic in nature and if the range is from 7-14 it will be alkaline in nature and the samples with value of pH as 7 will be considered as neutral.
The most important point to be noted is that pH is the property of aqueous solutions only.
Now let’s solve this question, since the given compound given is citric acid we know that the citric acid is a substance which is made up of solid crystals and hence we cannot find its pH as such.
We have to dissolve the crystals in the solvent to make the solution and then the solution is studied
We cannot exactly say the pH of citric acid or any acid since the pH will change with dilution of the acid.
We know that citric acid is an organic acid and is also a weak acid and they will have a pH range from 3-6 and the pH value changes with the dilution of the acid as the molar concentration of the solution changes.

Note: Pure substances like sodium hydroxide, ammonium sulphate etc. will not have pH value and they have to be dissolved in a solution and get ionized to show the pH value since it depends on the concentration of $H^{+}$ ions. The only pure substance which has the pH value is water and it has a pH value 7. We can measure the pH of a substance using a pH paper which gives that the substance is an acid or base, but using the pH meter we could accurately find the pH value of any substance.