Question

A solution has a pH of 4.20. Using the relationship between pH and pOH, what is the concentration of OH?? A. 9.9 × 10-1 M B. 6.2 × 10-1 M C. 6.3 × 10-5 M D. 6.7 × 10-6 M E. 1.6 × 10-10M

Answer 1

The correct answer is option E.

Explanation:

The pH of the solution is defined as negative logarithm of hydrogen ions  concentration in a solution. Mathematically written as:

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

The pOH of the solution is defined as negative logarithm of hydroxide ions  concentration in a solution. Mathematically written as:

$pOH=-\log[OH^-]$

The sum of ph and pOH is equal to 14.

pH + pOH = 14

A solution has a pH of 4.20.

$pOH=14-pH=14-4.20=9.8$

$pOH=9.8=-\log[OH^-]$

$[OH^-]=1.58\times 10^{-10} M\approx 6.0\times 10^{-10} M$

Hence, the correct answer is option E.