Question

Five solutions A, B, C, D and E when tested with pH paper showed pH as 4, 1, 13, 7 and 10 respectively. Which solution is:
(1) Strongly acidic (2) Strongly alkaline (3) Weakly acidic (4) Neutral and (5) Weakly alkaline? Arrange the solutions in increasing order of H⁺ ion concentration.

Answer 1

Step 1: Analyzing the pH values:
The pH scale ranges from 0 to 14, where:
- pH less than 7 indicates an acidic solution (stronger acid as pH decreases).
- pH greater than 7 indicates an alkaline (basic) solution (stronger base as pH increases).
- pH equal to 7 indicates a neutral solution.

Step 2: Identifying the type of each solution based on its pH:
1. Solution A has a pH of 4 – This is a weakly acidic solution, as pH values between 4 and 6 are mildly acidic.
2. Solution B has a pH of 1 – This is a strongly acidic solution, as pH values between 0 and 3 indicate strong acids.
3. Solution C has a pH of 13 – This is a strongly alkaline solution, as pH values between 11 and 14 are strongly basic.
4. Solution D has a pH of 7 – This is a neutral solution, as pH 7 is neutral (pure water).
5. Solution E has a pH of 10 – This is a weakly alkaline solution, as pH values between 8 and 10 are mildly alkaline.

Step 3: Ordering the solutions based on H⁺ ion concentration:
The H⁺ ion concentration is inversely related to the pH value. A lower pH corresponds to a higher concentration of H⁺ ions.
- Solution B (pH 1) has the highest H⁺ concentration (strong acid).
- Solution A (pH 4) has a higher H⁺ concentration than neutral or basic solutions (weak acid).
- Solution D (pH 7) is neutral with equal concentrations of H⁺ and OH^-.
- Solution E (pH 10) has a lower H⁺ concentration than neutral solutions (weak base).
- Solution C (pH 13) has the lowest H⁺ concentration (strong base).

Step 4: Conclusion:
The solutions are:
1. Solution B – Strongly acidic
2. Solution A – Weakly acidic
3. Solution D – Neutral
4. Solution E – Weakly alkaline
5. Solution C – Strongly alkaline

The solutions arranged in increasing order of H⁺ ion concentration are:
Solution C < Solution E < Solution D < Solution A < Solution B