Question

What is the pH of a solution with a concentration of 4.2 × 10–5 M H3O+? 2.31 4.38 5.62 6.87

Answer 1

Answer : The pH of the solution is, 4.38

Explanation :

pH : It is defined as the negative logarithm of hydrogen ion or hydronium ion concentration.

Formula used :

$pH=-\log [H_3O^+]$

Now put the value of hydronium ion concentration in this formula, we get the value of pH.

$pH=-\log (4.2\times 10^{-5})$

$pH=4.38$

Therefore, the pH of the solution is, 4.38

Answer 2

Answer;

pH = 4.38

Explanation;

Consider that ;

[H3O+] = 10-pH mol/L  

 Therefore; the pH is the -log of the [hydronium ion].  

pH = - log [H3O+]

Thus;

pH = - log (4.2 × 10^–5)

     = 4.38