AP Chemistry : pH
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Example Questions
Example Question #31 : Reactions And Equilibrium
Find the pH of a 0.2M calcium hydroxide solution.
Since every calcium hydroxide molecule will dissociate and form two hydroxide ions, the concentration of the hydroxide ions will be twice as much as the initial concentration of the base.
This means that the concentration of hydroxide ions in the solution will be 0.4M.We can use this concentration to solve for the pOH fo the solution.
Since we are looking for the pH of the solution, we simply subtract the pOH form 14.
This results in a pH of 13.6.
Example Question #31 : Acid Base Reactions
Which of the following is a possible pH value for a basic solution?
None of these
Basic solutions have a pH level greater than 7, which is the neutral pH. Acidic solutions have a pH level lower than 7.
Example Question #32 : Reactions And Equilibrium
Which of the following is considered a neutral pH?
Basic solutions have a pH level greater than 7 and acidic solutions have a pH level lower than 7. A pH of 7 corresponds to a neutral solution.
Example Question #33 : Reactions And Equilibrium
A chemist has an unknown solution. He think the solution is an acid. Which of the following pH's would support his hypothesis?
None of these
Acidic solutions have a pH level lower than 7, which is the neutral pH. Basic solutions have a pH level greater than 7.
Example Question #35 : Reactions And Equilibrium
Knowing that the acid ionization constants of 
have an acidic pH
None of the other answers
have a pH greater than 7
exhibit a neutral pH because 
have a pH greater than 7
Potassium sulfide is soluble in water yielding the specie 
The respective hydrolysis constants are:
Analyzing the rounded values of both hydrolysis constants, we can see that the value of 
Example Question #36 : Reactions And Equilibrium
Consider the following reaction of acetic acid:
The pKa for this reaction is 
This question is presenting us with a reversible chemical reaction of a weak acid. It provides us with the pKa of the acid, and asks us to determine where on the pH spectrum will the acidic form of acetic acid be equal to its basic form.
There is a very important concept that this question highlights, which is that a compound will always have equal amounts of its acidic and basic forms at a pH that is equal to its pKa. This can be shown mathematically by using the Henderson-Hasselbalch equation.
As the above equation shows, when the acidic and basic forms are equal, their ratio is equal to 
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