Titration Errors

Question 1

How do we clean burette and pipette

Answer 1

The burette and pipette should first be washed with tap water, then deionised water, and finally with the solution it is meant to contain.

Question 2

How do we clean the conical flask

Answer 2

The conical flask should only be rinsed with water and deionised water, and not with the analyte solution.

Question 3

What is the effect of washing the burette with the analyte?

Answer 3

The recorded volume of titrant will be higher than expected.

-Residual analyte will remain in the burette.
-Upon adding the expected volume of titrant to the burette, the solutions will react prematurely before the titration begins.
-This makes the concentration of the titrant solution in the burette lower than expected
-Thus a higher volume of the titrant will be required to react and reach the end point of the expected concentration and volume of analyte in conical flask.

Question 4

What is the effect of washing the conical flask with the analyte?

Answer 4

The recorded volume of titrant will be higher than expected.

-Residual analyte will remain in the conical flask.
-Upon adding the expected volume of analyte, the total number of moles of analyte solution is higher than expected.
-When the titrant is added to the conical flask, a higher than expected volume will be required to reach the end point, as the total number of moles required by the titrant increases to react with the increased number of moles of analyte.
The recorded volume of titrant will be higher than expected.

Question 5

What is the effect of washing the conical flask with the titrant?

Answer 5

The recorded volume of titrant will be lower than expected.

-Residual titrant will remain in the conical flask.
-Upon adding the expected volume of analyte, the solutions will react prematurely before the titration begins.
-This makes the concentration of the analyte solution in the conical flask to be lower than expected.
-Thus a lower volume of titrant with the expected volume and concentration will be required to react and reach the end point of the lowered concentration of analyte.

Question 6

What is the effect of air bubbles in the pipette or burette?

Answer 6

The actual volume of solution delivered is less than the recorded volume.

-If a bubble is in the burette, its expulsion during titration will lead to a higher than expected recorded volume of titrant.
-If a bubble is in the pipette, the volume of analyte transferred to the conical flask will be lesser than expected

Question 7

What is the effect of reactive impure analyte reacting?

Answer 7

The recorded volume of titrant will be higher than expected.

-Impurities within the analyte (e.g., impure sodium hydroxide crystals) react with the titrant
-This will lead to the calculated percentage purity being higher than the actual value

Question 8

What is the effect of unreactive impure analyte reading?

Answer 8

The recorded volume of titrant will be lower than expected.

-Impurities within the analyte will not react
-Only the pure, reactive substance in the impure analyte will react, which is lesser than expected
-With the addition of the expected concentration titrant, lesser volume will be required to completely react and reach the end point.

Question 9

What is the effect of the presence of deionised water in the conical flask?

Answer 9

The recorded volume of titrant will be UNCHANGED.

There is no effect on the volume of titrant (B) required as the number of moles of analyte (acid) in conical flask remains the same

Question 10

What is the effect of the presence of deionised water in the burette?

Answer 10

The recorded volume of titrant will be higher than expected.

-The presence of deionised water will contribute to the total volume of titrant, diluting it, causing the concentration of the titrant to be lower than expected.
-Thus a larger volume of the diluted titrant will be required to react completely and reach the end point with the expected volume and concentration of analyte.

Question 11

What is the effect of the presence of deionised water in the pipette?

Answer 11

The recorded volume of titrant will be lower than expected.

-The presence of deionised water will contribute to the total volume of analyte, diluting it, causing the concentration of analyte to be lower than expected.
-Thus a smaller volume of the expected volume and concentration of the titrant will be required to react completely and reach the end point with the diluted analyte.

Question 12

Consistently misses the end point. What is the effect on calculation? Eg. calculating the volume of water molecules in an anhydrous compound to form the crystal

Answer 12

-As the volume of titrant added is slightly higher than it should be, the number of moles of C2H2O4 calculated will be slightly higher.
-x will still remain as the same number as the calculated value of x is rounded off (to the same number).