Hydronium Ion Concentration in an Alkaline Solution

In chemical systems, understanding the relationship between the hydronium ion concentration, H3O , and the hydroxide ion concentration, OH-, is crucial for determining the acidity or basicity of a solution. This article delves into the calculation of the hydronium ion concentration in a given solution, highlighting the use of autoprotolysis and the significance of pH and pOH.

Autoprotolysis and the Autoprotolysis Constant (Kw)

Water undergoes an autoprotolysis reaction, which can be represented as:

H2O H3O OH-

Under standard conditions, this reaction is quantified by the autoprotolysis constant, Kw, such that:

KW [H3O ][OH-] 10-14

By taking the negative logarithm on both sides, we derive the relationship:

pH pOH 14

Calculating Hydronium Ion Concentration

Given the hydroxide ion concentration, OH- 1.3 × 10-3, mol/L, we can calculate the hydronium ion concentration as follows:

First, calculate the pOH:

pOH -log10(OH-) -log10(1.3 × 10-3) 2.89

Next, determine the pH:

pH 14 - pOH 14 - 2.89 11.11

Finally, calculate the hydronium ion concentration, H3O , from the pH:

[H3O ] 10-pH 10-11.11 7.86 × 10-12 mol/L

Conclusions

From these calculations, we can see that the solution is an alkaline solution, given the high pH (11.11). This calculation illustrates the importance of understanding the autoprotolysis of water and how it relates to pH and pOH values, aiding in the analysis of chemical solutions.

Related Keywords

hydronium ion concentration, pH, pOH, autoprotolysis