Question

Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively.
1. Arrange the pH in increasing order of hydrogen-ion concentration.
2. Which solution is
(a) neutral?
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?

Answer 1

1. $pH=-log\left[H^{+}\right]$

The pH can be arranged in the increasing order of the concentration of hydrogen ions as: 11 < 9 < 7 < 4 < 1.

2.
(a) Solution D has pH = 7, hence its neutral

(b) Higher the pH, more alkaline is the solution.
Solution C with pH 11 is strongly alkaline.

(c) Lower the pH, more acidic is the solution.
Hence, solution B with pH 1 is strongly acidic.

(d)Lower the pH, more acidic is the solution.
Therefore, solution A with pH 4 is weakly acidic.

(e) Higher the pH, more alkaline is the solution.
Solution E with pH 9 is weakly alkaline.