All High School Chemistry Resources
Example Questions
Example Question #1 : Identifying Unknown Volume
Starting with 75mL of a .030M solution, how many milliliters of .022M solution are needed to titrate it?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the volume of the base:
Plug in known values and solve.
Example Question #2 : Identifying Unknown Volume
Starting with 12mL of a .015M solution, how many milliliters of .000M solution are needed to titrate it?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the volume of the base:
Plug in known values and solve.
Example Question #3 : Identifying Unknown Volume
Starting with 50mL of a .015M solution, how many milliliters of .010M solution are needed to titrate it?
None of these
For this question use the following formula:
is the number of acidic hydrogens on the acid, is the molarity of the acid, is the volume of the acid, is the number of basic hydroxides on the base, is the molarity of the base, is the volume of the base
Rearrange the equation for the volume of the base:
Plug in known values and solve.
Example Question #41 : Reaction Types
A buffer using acetic acid (pKa=4.76) is titrated with NaOH. What is the pH at half the equivalence point?
4.76
12.36
2.38
9.52
7.00
4.76
The pH at half the equivalence point is equal to the pKa of the acid.
Example Question #1 : Titrations And Indicators
At what pH does the equivalence point lie for a strong-acid / strong-base titration?
Slightly basic
Slightly acidic
It is impossible to determine
7
7
The equivalence point for a strong-acid / strong-base titration will be at neutral pH, 7. This is because each equivalent of the acid will neutralize each equivalent of the base, and you will be left with a neutral solution.
Example Question #1 : Titrations And Indicators
At what pH does the equivalence point lie for a strong-acid / weak-base titration?
7
Slightly acidic
It is impossible to determine
Slightly basic
Slightly acidic
The equivalence point for a strong-acid / weak-base titration will be at a slightly acidic pH. This is because the acid is stronger and dissociates to a greater degree, while the base is not quite as strong, so doesn't dissociate to a large enough extent to neutralize each equivalent of the acid.
Example Question #1 : Titrations And Indicators
At what pH does the equivalence point lie for a weak acid-strong base titration?
7
Slightly acidic
It is impossible to determine
Slightly basic
Slightly basic
The equivalence point for a weak-acid / strong-base titration will be at a slightly basic pH. This is because the base is stronger and dissociates to a greater degree, while the acid is not quite and strong and doesn't dissociate to a large enough extent to neutralize each equivalent of the base.
Example Question #2 : Help With Titration Curves
You are given 500 mL of a HCl solution of unknown concentration and you titrate is with 0.0540 M NaOH. It takes 32.1 mL of the NaOH solution to reach your end point. What is of your original solution?
None of the available answers.
First, let us write out the reaction that occurs:
Example Question #2 : Titrations And Indicators
A titration is a drop-by-drop mixing of an acid and a base in order to determine the concentration of an unknown solution, via addition of a solution with known concentration. A titration curve can be graphed showing the relationship between the mixture pH and the amount of known solution added.
What would the titration curve look like for a strong base being titrated with a strong acid?
A positively sloped line
A decreasing sigmoidal curve
An increasing sigmoidal curve
A negatively sloped line
A decreasing sigmoidal curve
There are two things to consider here.
1. Since the solution is originally a strong base, the pH will be originally elevated. As a strong acid is added to the solution, the pH will decrease. As a result, the titration curve will be decreasing as the volume of titrant increases.
2. The titration curve will never be a straight line. Eventually, the strong acid will be much larger in volume than the original base; however, the pH will eventually even out at the pH of the added titrant.
Since we are titrating a strong base with a strong acid, the titration curve will be represented by a decreasing sigmoidal curve.
Example Question #4 : Help With Titration Curves
Where does the flattest region of a titration curve of the titration of a weak acid with a strong base occur?
At a pH greater than 7
At the pKa of the acid
At the pKb of the base
At a pH of 7
At the pKa of the acid
In this question, titration curve would graph the pH of acid solution versus the amount of base added. Since the base is strong and the acid is weak, we can conclude that the pH will be slightly greater than 7 at the equivalence point. The equivalence point is found in the steepest region of the curve.
The half-equivalence point is the flattest region of the titration curve and is most resistant to changes in pH. This corresponds to the pKa of the acid. Within this region, adding base (changing the x-value) results in very little deviation in the pH (the y-value). This region is also the buffer region for the given acid.