Undertaking titrations and colorimetry
Contents
Making a standard solution ......................................................................................... 3
Aim ......................................................................................................................... 3
Calculations............................................................................................................ 3
Calculation of Theoretical mass .............................................................................. 3
Calculation for actual mass, number of moles and concentration of sodium
carbonate: .............................................................................................................. 4
Equipment .............................................................................................................. 5
Risk assessment ..................................................................................................... 5
Procedure ............................................................................................................... 5
Accuracy ................................................................................................................. 6
Titrations .................................................................................................................... 7
Titration of our standard solution ................................................................................ 7
Aim ......................................................................................................................... 7
Risks ....................................................................................................................... 7
Equipment for titration ............................................................................................ 8
Method.................................................................................................................... 8
Results .................................................................................................................... 8
Calculations............................................................................................................ 9
Accuracy ............................................................................................................... 10
Calculations based on the value the teacher has instructed me to use: ................. 11
Titration of sodium hydroxide solution ...................................................................... 12
Risks ..................................................................................................................... 12
Equipment for titration .......................................................................................... 13
Method.................................................................................................................. 13
Results .................................................................................................................. 14
Calculation of mean titre ....................................................................................... 14
Calculating the concentration of sodium hydroxide: .............................................. 15
1
,Undertaking titrations and colorimetry
Titration of sodium hydroxide with hydrochloric acid (using a pH meter) ................... 16
Aim ....................................................................................................................... 16
Equipment ............................................................................................................ 16
Method.................................................................................................................. 17
Table ..................................................................................................................... 18
Calculations.......................................................................................................... 19
Colorimetry .............................................................................................................. 21
Aim ....................................................................................................................... 21
Risk assessment ................................................................................................... 21
Equipment ............................................................................................................ 21
Method.................................................................................................................. 22
Absorbance tables ................................................................................................ 22
About the calibration curve: .................................................................................. 24
Why we undertake certain safety precautions and techniques in order to mitigate risk
................................................................................................................................. 25
Evaluation ................................................................................................................ 26
Evaluation of Making a standard solution .............................................................. 26
Evaluation of titration of standard solution ............................................................ 26
Evaluation of Titration of sodium hydroxide solution.............................................. 27
Evaluation of Titration of sodium hydroxide solution with pH meter ....................... 28
Evaluation of colourimetry .................................................................................... 29
Comparing my results to the rest of the class ........................................................... 31
Calibration Report .................................................................................................... 34
Calibrating pipette and burette.............................................................................. 34
Equipment ............................................................................................................ 34
Method for calibrating pipette and burette ............................................................ 35
Percentage error calculations ............................................................................... 36
2
,Undertaking titrations and colorimetry
Making a standard solution
Aim
To prepare a 250cm3 solution of 0.0125 moles of sodium carbonate of a Concentration of
0.1mol/dm3
Calculations
Calculation of Theoretical mass
To determine the mass of sodium carbonate we’d need for the standard solution, we used
this equation:
𝑀𝑎𝑠𝑠
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑓𝑜𝑟𝑚𝑢𝑙𝑎 𝑚𝑎𝑠𝑠
Mr of sodium carbonate: 105.9888
Number of moles: 0.0125 as that was the amount in the HCl so we need that many moles
of sodium carbonate.
0.0125𝑚𝑜𝑙𝑒𝑠 × 105.9888 = 1.320𝑔
1.320g of sodium carbonate is required to make a standard solution
3
, Undertaking titrations and colorimetry
Calculation for actual mass, number of moles and concentration of sodium
carbonate:
Actual mass sodium carbonate = 1.32g
𝑚𝑎𝑠𝑠
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 =
𝑀𝑟
1.32
= 0.0125
105.9888
Number of moles of sodium carbonate = 0.0125
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠
= 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛
𝑉𝑜𝑙𝑢𝑚𝑒
0.0125
= 0.05
250 ÷ 1000
Concentration of sodium carbonate = 0.05mol/dm3
4
Contents
Making a standard solution ......................................................................................... 3
Aim ......................................................................................................................... 3
Calculations............................................................................................................ 3
Calculation of Theoretical mass .............................................................................. 3
Calculation for actual mass, number of moles and concentration of sodium
carbonate: .............................................................................................................. 4
Equipment .............................................................................................................. 5
Risk assessment ..................................................................................................... 5
Procedure ............................................................................................................... 5
Accuracy ................................................................................................................. 6
Titrations .................................................................................................................... 7
Titration of our standard solution ................................................................................ 7
Aim ......................................................................................................................... 7
Risks ....................................................................................................................... 7
Equipment for titration ............................................................................................ 8
Method.................................................................................................................... 8
Results .................................................................................................................... 8
Calculations............................................................................................................ 9
Accuracy ............................................................................................................... 10
Calculations based on the value the teacher has instructed me to use: ................. 11
Titration of sodium hydroxide solution ...................................................................... 12
Risks ..................................................................................................................... 12
Equipment for titration .......................................................................................... 13
Method.................................................................................................................. 13
Results .................................................................................................................. 14
Calculation of mean titre ....................................................................................... 14
Calculating the concentration of sodium hydroxide: .............................................. 15
1
,Undertaking titrations and colorimetry
Titration of sodium hydroxide with hydrochloric acid (using a pH meter) ................... 16
Aim ....................................................................................................................... 16
Equipment ............................................................................................................ 16
Method.................................................................................................................. 17
Table ..................................................................................................................... 18
Calculations.......................................................................................................... 19
Colorimetry .............................................................................................................. 21
Aim ....................................................................................................................... 21
Risk assessment ................................................................................................... 21
Equipment ............................................................................................................ 21
Method.................................................................................................................. 22
Absorbance tables ................................................................................................ 22
About the calibration curve: .................................................................................. 24
Why we undertake certain safety precautions and techniques in order to mitigate risk
................................................................................................................................. 25
Evaluation ................................................................................................................ 26
Evaluation of Making a standard solution .............................................................. 26
Evaluation of titration of standard solution ............................................................ 26
Evaluation of Titration of sodium hydroxide solution.............................................. 27
Evaluation of Titration of sodium hydroxide solution with pH meter ....................... 28
Evaluation of colourimetry .................................................................................... 29
Comparing my results to the rest of the class ........................................................... 31
Calibration Report .................................................................................................... 34
Calibrating pipette and burette.............................................................................. 34
Equipment ............................................................................................................ 34
Method for calibrating pipette and burette ............................................................ 35
Percentage error calculations ............................................................................... 36
2
,Undertaking titrations and colorimetry
Making a standard solution
Aim
To prepare a 250cm3 solution of 0.0125 moles of sodium carbonate of a Concentration of
0.1mol/dm3
Calculations
Calculation of Theoretical mass
To determine the mass of sodium carbonate we’d need for the standard solution, we used
this equation:
𝑀𝑎𝑠𝑠
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑓𝑜𝑟𝑚𝑢𝑙𝑎 𝑚𝑎𝑠𝑠
Mr of sodium carbonate: 105.9888
Number of moles: 0.0125 as that was the amount in the HCl so we need that many moles
of sodium carbonate.
0.0125𝑚𝑜𝑙𝑒𝑠 × 105.9888 = 1.320𝑔
1.320g of sodium carbonate is required to make a standard solution
3
, Undertaking titrations and colorimetry
Calculation for actual mass, number of moles and concentration of sodium
carbonate:
Actual mass sodium carbonate = 1.32g
𝑚𝑎𝑠𝑠
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠 =
𝑀𝑟
1.32
= 0.0125
105.9888
Number of moles of sodium carbonate = 0.0125
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑜𝑙𝑒𝑠
= 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛
𝑉𝑜𝑙𝑢𝑚𝑒
0.0125
= 0.05
250 ÷ 1000
Concentration of sodium carbonate = 0.05mol/dm3
4
