Question

(a) The pH of a cold drink is 5. What will be its action on blue and red litmus solutions?
(b) The pH values of three acids A, B, and C having equal molar concentrations are 5.0, 2.8 and 3.5 respectively. Arrange these acids in order of the increasing acid strengths.

Answer 1

Hint: pH is the negative logarithm of hydrogen ion concentration. It is the most common way to determine the strength of acid or base. It is often termed as the potential of hydrogen ions.

Complete step by step answer:
- All the chemicals have their distinct nature, which is they can be neutral acid or basic. This characteristic depends on how many H^{+} or OH^{-} ions a particular chemical is releasing in its aqueous solution.
- pH is the molarity of H^{+} ions.
- Chemicals that release H^{+} ions are acidic, whereas those which release OH^{-} ions are acidic.
- The pH value of different chemicals varies on a scale from 0 to 14
Basic: pH is greater than 7
Acid: pH is less than 7
Neutral: pH is equal to 7
- As the pH given in the question is 5, cold drink is acidic in nature. So, it will turn blue litmus red. It will show no change on red litmus paper.
- As we know that pH increases with the decrease in acidic character. So, sample B will have maximum acid strength.
Thus, the order of increasing acidic strength will be B > C > A.

Note: A pH scale is used to determine the nature of a substance. The scale is logarithmic, ranging from 0 to 14. This suggests that if an integral value increases or decreases, the concentration changes tenfold, accordingly.