What is the difference between these two??
Answers
This is also true for the [H+] ion and the [OH-] ion. Remember that pH and pOH measure these ions, so if pH and pOH are changing so is the [H+] and the [OH-] ions. When solutions of acids and bases are made, they are usually dissolved in water. The more [H+] ions that are in solution, the more acidic the solution is.
Water
Sometimes water collides with another water molecule with enough force to transfer hydrogen.
The result is a hydroxide ion (OH-) that is a base and hydronium ion (H3O+), which is an acid.
This is known as self-ionization of water.
Neutral
In pure water at 25oC the concentration of [H+] and the concentration of [OH-] are each only 1.0 x 10-7 M.
what this means is the concentration of [H+] and [OH-] are equal and is described as a neutral solution
Water constant
In most cases [H+] and [OH-] are interdependent meaning that when [H+] increases [OH-] decreases and vis versa.
For aqueous solutions, the product of hydrogen ion concentration and hydroxide ion concentration equals 1.0 x 10-14
[H+] x [OH-] = 1.0 x 10-14
The product of the concentrations of the hydrogen ions and the hydroxide ions in water is called the ion-product constant for water (Kw)
Kw = [H+] x [OH-] = 1.0 x 10-14
Acids and Bases Numerically
Not all solutions are neutral, when this happens the hydrogen ion concentration is greater than the hydroxide ion concentration and is known as an acidic solution. Which means that [H+] is greater than 1.0 x 10-7 M
A base is a solution with a larger hydroxide ion concentration than the hydrogen ion concentration. Which means that [H+] is less than 1.0 x 10-7 M. Basic solutions are known as alkaline solutions.
Example Prob(Copy all)
Ex prob
If the [H+] is 1.0 x 10-5 M, is this solution acidic, basic, or neutral? What is the [OH-] of this solution?
If the concentration of [H+] is more than 1.0 x 10-7 then it is an acidic solution
To determine the [OH-] use the Kw information and substitute the knowns.
Kw = [H+] x [OH-] = 1.0 x 10-14
We know Kw = 1.0 x 10-14 and [H+] = 1.0 x 10-5 so rearrange for [OH-] and solve
Kw= [OH-] so 1.0 x 10-14 = 1.0 x 10-9 M
[H+] 1.0 x 10-5 M