Metal cations can act as lewis acids in water to produce an acidic solution even though the metal ion contains no hydrogen. Water hydrates the ions in solution and partial loss of electrons from water allows hydrogen ion to be lost
What is the pH of a 0.1209M solution of Al3+ ions, if it has a Ka of 1.400*10-5?
Al(H2O)6(3+)==>Al(H2O)5(OH^-)(2+) + H^+
Write the Ka expression, set up an ICE chart, substitute into the Ka expression and solve for H^+, then convert to pH.
To find the pH of a solution of Al3+ ions, we need to consider that Al3+ ions can act as Lewis acids and react with water to produce an acidic solution.
The reaction for Al3+ ions with water can be written as:
Al3+ + H2O → AlOH2+ + H+
In this reaction, Al3+ ions react with water molecules to form hydrated aluminum ions (AlOH2+) and release a hydrogen ion (H+).
Since the Ka value is given as 1.400*10^-5, we can use this to calculate the concentration of H+ ions in the solution.
First, let's find the concentration of Al3+ ions in the solution. The concentration of Al3+ ions is given as 0.1209M.
Next, we need to determine the concentration of H+ ions in the solution. This concentration will be equal to the concentration of AlOH2+ ions formed in the reaction, as one hydrogen ion is released for each AlOH2+ ion formed. Since Al3+ ions and AlOH2+ ions have the same concentration, we can consider the concentration of H+ ions to be equal to the concentration of Al3+ ions.
So, the concentration of H+ ions in the solution is 0.1209M.
Now, we can calculate the pH using the formula:
pH = -log[H+]
Substituting the concentration value:
pH = -log(0.1209)
Using a calculator, we find that pH is approximately 0.92.
Therefore, the pH of the 0.1209M solution of Al3+ ions is 0.92.