Given:

[H⁺] = 3.8 × 10^–3 M

To calculate of pH, we apply the formula

pH = -log[H⁺]

or pH = log

where pH is defined as the negative logarithm of the concentration (in mol per litre) of hydrogen ions which it contain or pH of the solution is the logarithm of the reciprocal of H⁺ ion concentration.

pH = -log [H⁺]

⇒pH = -log (3.8 × 10^–3)

⇒pH = -log 3.8 – log 10^-3

⇒pH = -log 3.8 – (-3 log 10)

⇒pH = -0.58 + 3

⇒pH = 2.42

Thus, pH value of soft drink is 2.42