Titration and colorimetry report:
I have recently began working as a technical assistant at a forensics lab known as CrimeSolve. As I have just
joined this and wish to successfully progress in my role over time, I will be required to prove that I am
capable in a number of different practical skills and practices. To do this, my job is to make sure that all of
the necessary equipment is calibrated, and that all of the equipment and the chemicals are safely checked.
Another part of my job is to make as well as test different standard solutions by using titration and
colorimetry methods as skilfully and accurately as possible. I have shown that I have done this throughout
this report by using evidence of me having done the practicals, as well as having wrote down my results,
calculations and evaluations of the skills and techniques I had used. I have also written down ideas for
possible future improvements that I can make when doing future experiments. So, when going through this
report, I had completed a number of practicals, all ultimately to find the concentration of our hydrochloric
acid and sodium hydroxide through titration, as well as to find the concentrations of the two unknown
substances through the method of colorimetry. To begin with, I had accurately calibrated all of the
necessary equipment for these practicals, so the necessary equipment to calibrate were my scales, a pH
meter, and a pipette. Once this was successfully done, I could begin with titration and later my colorimetry.
Calibration of balance:
So, to start of our experiment, I was required to calibrate some weighing scales, so as I could use them later
not only to calibrate our pipette for later on, but to also weigh out our sodium carbonate and copper (ll)
sulfate accurately to make my stock solutions. In order to do this, we had placed various different weights
onto out scales, and had recorded the labelled mass that was written on each weight, and we recorded the
balance reading. After this, I had taken time to work out the percentage error of each weight, so as later on
I can now work out how inaccurate the balance is, so as I can adjust my results. It was very important that I
level the balance before I had began using it. This is to ensure that my results were as accurate as possible,
as having a sensitive balance could affect the results I get. If I was to have leaned on the workspace whilst
measuring the weights, this would have made my result less accurate as well as reliable.
Results-
Labelled mass: (g) Balanced reading: (g) Percentage error: (%)
2.00 2.02 1
1.00 0.99 1
5.00 5.01 0.2
200.00 200.14 0.07
100.00 100.10 0.1
50.00 50.02 0.04
When working out the percentage error, I had looked at the labelled mass of each weight and found the
different between the balanced reading. So, for the first result, it is 2.00g, and the balanced reading is
2.02g, so the difference is 0.02g. So, the equation used to work this out is the difference/labelled mass x
100: 0.02/2x100= 1%.
Calibration of pipette:
Now that I have successfully calibrated the balance, I was then able to calibrate our pipette. To do this I
filled the pipette with 25.00cm3 of water, so up to the calibration line shown on the pipette, and then I had
, to transfer this into a beaker that had been placed onto the already calibrated scales. 25.00cm 3 in the
pipette should be the same as 25.00g on our scales, so it is easy to work out the percentage error of the
pipette this way.
Once this was done, the reading shown on the scales was 25.08g, so there was a 0.08g difference. So, now
knowing this I could work out the percentage error of my pipette using the same equation that I had used
when working this out for my balance. 0.08/25x100=0.32% error.
Preparation of primary standard solution of sodium carbonate:
Now that the equipment has been successfully calibrated, I could then prepare my standard solution of
sodium carbonate which will be used in the standardisation of my hydrochloric acid to find out the
concentration of it.
Method-
1. To begin, first weigh out 1.33g exactly of sodium carbonate into a weighing boat and use the same
calibration for the balance that was worked out beforehand. Place the weighing boat onto the
scales and zero it, then start transferring the solid sodium carbonate into a 250cm 3 beaker. To
ensure that all the solid that was transferred goes in, rinse the weighing boat with distilled water
into the beaker that all of the solid was transferred into.
2. Next, keep adding water until all of the solid is able to dissolve, and do this whilst mixing the
solution with a glass rod. If it is difficult to dissolve, use warm water to make the process quicker.
3. Put the solution into a clean 250cm3 volumetric flask using a funnel, to ensure that none of the
solution is spilled. Then rinse the beaker to get all of the solution out as well as the glass rod and
funnel and pour it into the volumetric flask.
4. Fill the flask up until it is just below the mark with tap water, and then use the water bottle.
5. Keep adding water with a plastic pipette until the bottom of the meniscus is exactly on the mark, to
ensure too much is not added. Then insert the stopper, and tip it from side-to-side multiple times to
completely mix it together.
6. Write your initials on the volumetric flask and leave it somewhere safe for use later.
Now that I have successfully completed this practical and have prepared my sodium carbonate solution
ready for my next practical, I then was able to work out the concentration of the solution. For this I will
need to use these two equations: Moles=mass/Mr, and concentration=moles/volume (dm 3). The mass of
the sodium carbonate used was 1.33g, and the Mr is 106: 1.33/106=0.012547. Now that I have the moles, I
can now work out the concentration: 0.012547/0.25=0.502moldm -3.
Standardisation of hydrochloric acid by titration:
I have now prepared my solution to help me to complete this practical to get the concentration of the
hydrochloric acid, so I am now able to conduct my first titration. I had done this same titration 4 times in
total, the first try being a rough trial to get a general idea as to how much acid is needed for the full
reaction to take place, so as for the next three runs I can be more accurate and careful with how much acid
I’m adding before it reaches the end point.
The end point is when we have added enough of the acid to our base to complete our reaction, we can find
out what the end point is by either using an indicator or a pH meter. The end point is shown to us when the
I have recently began working as a technical assistant at a forensics lab known as CrimeSolve. As I have just
joined this and wish to successfully progress in my role over time, I will be required to prove that I am
capable in a number of different practical skills and practices. To do this, my job is to make sure that all of
the necessary equipment is calibrated, and that all of the equipment and the chemicals are safely checked.
Another part of my job is to make as well as test different standard solutions by using titration and
colorimetry methods as skilfully and accurately as possible. I have shown that I have done this throughout
this report by using evidence of me having done the practicals, as well as having wrote down my results,
calculations and evaluations of the skills and techniques I had used. I have also written down ideas for
possible future improvements that I can make when doing future experiments. So, when going through this
report, I had completed a number of practicals, all ultimately to find the concentration of our hydrochloric
acid and sodium hydroxide through titration, as well as to find the concentrations of the two unknown
substances through the method of colorimetry. To begin with, I had accurately calibrated all of the
necessary equipment for these practicals, so the necessary equipment to calibrate were my scales, a pH
meter, and a pipette. Once this was successfully done, I could begin with titration and later my colorimetry.
Calibration of balance:
So, to start of our experiment, I was required to calibrate some weighing scales, so as I could use them later
not only to calibrate our pipette for later on, but to also weigh out our sodium carbonate and copper (ll)
sulfate accurately to make my stock solutions. In order to do this, we had placed various different weights
onto out scales, and had recorded the labelled mass that was written on each weight, and we recorded the
balance reading. After this, I had taken time to work out the percentage error of each weight, so as later on
I can now work out how inaccurate the balance is, so as I can adjust my results. It was very important that I
level the balance before I had began using it. This is to ensure that my results were as accurate as possible,
as having a sensitive balance could affect the results I get. If I was to have leaned on the workspace whilst
measuring the weights, this would have made my result less accurate as well as reliable.
Results-
Labelled mass: (g) Balanced reading: (g) Percentage error: (%)
2.00 2.02 1
1.00 0.99 1
5.00 5.01 0.2
200.00 200.14 0.07
100.00 100.10 0.1
50.00 50.02 0.04
When working out the percentage error, I had looked at the labelled mass of each weight and found the
different between the balanced reading. So, for the first result, it is 2.00g, and the balanced reading is
2.02g, so the difference is 0.02g. So, the equation used to work this out is the difference/labelled mass x
100: 0.02/2x100= 1%.
Calibration of pipette:
Now that I have successfully calibrated the balance, I was then able to calibrate our pipette. To do this I
filled the pipette with 25.00cm3 of water, so up to the calibration line shown on the pipette, and then I had
, to transfer this into a beaker that had been placed onto the already calibrated scales. 25.00cm 3 in the
pipette should be the same as 25.00g on our scales, so it is easy to work out the percentage error of the
pipette this way.
Once this was done, the reading shown on the scales was 25.08g, so there was a 0.08g difference. So, now
knowing this I could work out the percentage error of my pipette using the same equation that I had used
when working this out for my balance. 0.08/25x100=0.32% error.
Preparation of primary standard solution of sodium carbonate:
Now that the equipment has been successfully calibrated, I could then prepare my standard solution of
sodium carbonate which will be used in the standardisation of my hydrochloric acid to find out the
concentration of it.
Method-
1. To begin, first weigh out 1.33g exactly of sodium carbonate into a weighing boat and use the same
calibration for the balance that was worked out beforehand. Place the weighing boat onto the
scales and zero it, then start transferring the solid sodium carbonate into a 250cm 3 beaker. To
ensure that all the solid that was transferred goes in, rinse the weighing boat with distilled water
into the beaker that all of the solid was transferred into.
2. Next, keep adding water until all of the solid is able to dissolve, and do this whilst mixing the
solution with a glass rod. If it is difficult to dissolve, use warm water to make the process quicker.
3. Put the solution into a clean 250cm3 volumetric flask using a funnel, to ensure that none of the
solution is spilled. Then rinse the beaker to get all of the solution out as well as the glass rod and
funnel and pour it into the volumetric flask.
4. Fill the flask up until it is just below the mark with tap water, and then use the water bottle.
5. Keep adding water with a plastic pipette until the bottom of the meniscus is exactly on the mark, to
ensure too much is not added. Then insert the stopper, and tip it from side-to-side multiple times to
completely mix it together.
6. Write your initials on the volumetric flask and leave it somewhere safe for use later.
Now that I have successfully completed this practical and have prepared my sodium carbonate solution
ready for my next practical, I then was able to work out the concentration of the solution. For this I will
need to use these two equations: Moles=mass/Mr, and concentration=moles/volume (dm 3). The mass of
the sodium carbonate used was 1.33g, and the Mr is 106: 1.33/106=0.012547. Now that I have the moles, I
can now work out the concentration: 0.012547/0.25=0.502moldm -3.
Standardisation of hydrochloric acid by titration:
I have now prepared my solution to help me to complete this practical to get the concentration of the
hydrochloric acid, so I am now able to conduct my first titration. I had done this same titration 4 times in
total, the first try being a rough trial to get a general idea as to how much acid is needed for the full
reaction to take place, so as for the next three runs I can be more accurate and careful with how much acid
I’m adding before it reaches the end point.
The end point is when we have added enough of the acid to our base to complete our reaction, we can find
out what the end point is by either using an indicator or a pH meter. The end point is shown to us when the
