Acid-base Titrations

Question 1

Titration

Answer 1

Accurately measure volume of 1 solution that reacts exactly with another solution
Used for finding concentrations, identification of unknowns, substance purity

Question 2

Volumetric flask error

100cm3

Answer 2

+- 0.20cm3

Question 3

Volumetric flask error

250cm3

Answer 3

+- 0.30cm3

Question 4

Pipette error

10cm3

Answer 4

+- 0.04cm3

Question 5

Pipette error

25cm3

Answer 5

+- 0.06cm3

Question 6

Burette error

50cm3

Answer 6

+- 0.10cm3

Question 7

How to use burrette

Answer 7

Bottom of meniscus to nearest half division

Run excess solution through tap to remove air

Question 8

How to use indicator

Answer 8

Few drops only, indicator is slightly acidic

Question 9

How to use mean titres

Answer 9

Concordant titres 0.10 for accuracy

Question 10

How to do titration calculations

Answer 10

Find mean titres
Stoichiometry
Concentration equation

Question 11

How to work out the moles used in the titration

Answer 11

Multiply the moles by the scale factor of the volumetric flask volume to find the actual number of moles used in the titration

Question 12

How to calculate the percentage by mass

Answer 12

Percentage by mass= mass of compound/ mass of total x 100

Question 13

How to do back titrations

Answer 13

Use all information given to you

Use balanced equations

Question 14

How to balance half equations in acidic conditions

Answer 14

Balance atoms other than H and O
Balance oxygen by adding water
Balance hydrogen by adding H+
Balance charges by adding electrons to +ve side

Question 15

Combining half equations

Answer 15

As reduction and oxidation happen at the same time, electrons should be equal on both sides