Titration and Colorimetry
Introduction:
In this report, I will talk about how I had prepared a standard solution using titrations. I will
be also including how to calibrate the equipment and the risk assessments to do with this
experiment. I will be determining the concentration of unknown solutions using titration and
colorimetry.
Part 1:
Calibrating the balance method:
I had first calibrated the balance. To do this we had to first wipe down the balance so that
there isn’t nothing on it. To start calibrating, we first held onto the M button until it flashes
500g. I had the 100g calibration balance, so then I had to press the T button 4 times until it
was 100g. Then we put on the calibration mass on the balance using a tweezer, we wait until
it says pass. After we have done all these steps, we had calibrated the balance.
Preparing the standard solution: Calculation of the mass of Sodium
carbonate required
Once we have calibrated the balance. We then calculate how much sodium carbonate that is
required. We need to first find the moles in order to calculate the mass.
Concentration = 0.10M
Volume = 250cm3
Volume in dm3 = 250/1000= 0.25dm3
Concentration = moles/0.25
0.10 = moles/0.25
0.10x0.25 = 0.025moles
Now that we have found the moles, we need to find the Mr so that we can calculate them to
find the mass.
Na2CO3
(23x2) + (12x1) + (16x3) = 106
Mass = Mr x moles
Mass = 0.025x106
Mass = 2.65g
Preparing the standard solution method:
We had worked out the mass no we had to make the required amount of sodium carbonate.
We had put a weighing boat on the balance and accurately put 2.65g of sodium carbonate.
Distilled water was used to clean of all the solution off the weighing boat so that there is none
left on it, we had poured it into a large beaker, where we had to dissolve all the sodium
carbonate using a stirring rod so that there were no bits of it left in it. A funnel was used to
pour the solution from the beaker into 250cm3 volumetric flask, keep pouring more distilled
water until the bottom of the meniscus touches the line using eye level so that the solution is
not above nor underneath the line. If it had gone above or underneath we would have to start
again and make the mass, we needed. A stopper had been placed on a volumetric flask so that
none of the solution was spilled. The flask would be inverted a few times so that all the
solution is spread out equally.
, Part 2:
Calibrating the pipette method:
The mass balance was already calibrated from part 1. A dry beaker was placed on the
balance. Using a glass pipette 25cm3 of water was transferred onto the dry beaker. The mass
of the water was recorded. To find the actual volume we used the formula:
volume of water = mass of water/density
The true value of water is 25cm3. We compared to see if it was within tolerance. If it was in
tolerance then we would use it, if not then we would have to repeat it again and replace it.
Calibrating the pipette calculations and result:
To calibrate the pipette, the balance had to be calibrated first. A dry beaker was placed on top
of it, and it would say 0. 25cm3 of water was transferred into a beaker and then I had recorded
the mass. My mass was 24.94g and the density of water is 0.9982. To find the volume I used
the formula:
Volume of water = mass of water/density of water
Volume of water = 24.94/0.9982
Volume of water = 24.98cm3
My result was intolerance so I wouldn’t have to repeat it again and my pipette is calibrated.
Setting up and performing the titration method.
When the pipette had been calibrated, 25cm3 of the sodium carbonate solution was
transferred into an 250cm3 conical flask, 2 drops of methyl orange indicator was added, and
we had swirled it, so the indicator was dissolved in the solution. Then we had to make sure
the burette was cleaned, once it was cleaned a funnel was used to pour hydrochloric acid until
it filled to 0, making sure the bottom of the meniscus touches the 0 line. Using the
hydrochloric acid, titrate the sodium carbonate solution, until you see a colour change occur.
Record the rough result first so then you get a rough idea of how the accurate results are
going to be around. The other 2 results were recorded accurately using eye level and drop by
drop so that we can see when the colour change had happened. Once the colour change
happened record both results down. Our rough result was 23, accurate was 23.4 and 23.4. so,
this means that our results are concordant, and we wouldn’t have to do another one. We need
to work the average by adding the 2 results and divide by 2.
23.4+23.4/2
46.8/2 = 23.4cm3
Results of titration including if results are concordant:
Rough: 23
Accurate: 1= 23.4, 2 = 23.4 (results are concordant)
Trial 1 2 Average
Volume 23.4 23.4 23.4
Calculations to determine the concentration of acid to 2dp:
To find the concentration we use the formula: concentration = moles/volume in dm3.
We first had to convert our average result into dm3 by dividing by 1000:
23.4/1000 = 0.0234
Introduction:
In this report, I will talk about how I had prepared a standard solution using titrations. I will
be also including how to calibrate the equipment and the risk assessments to do with this
experiment. I will be determining the concentration of unknown solutions using titration and
colorimetry.
Part 1:
Calibrating the balance method:
I had first calibrated the balance. To do this we had to first wipe down the balance so that
there isn’t nothing on it. To start calibrating, we first held onto the M button until it flashes
500g. I had the 100g calibration balance, so then I had to press the T button 4 times until it
was 100g. Then we put on the calibration mass on the balance using a tweezer, we wait until
it says pass. After we have done all these steps, we had calibrated the balance.
Preparing the standard solution: Calculation of the mass of Sodium
carbonate required
Once we have calibrated the balance. We then calculate how much sodium carbonate that is
required. We need to first find the moles in order to calculate the mass.
Concentration = 0.10M
Volume = 250cm3
Volume in dm3 = 250/1000= 0.25dm3
Concentration = moles/0.25
0.10 = moles/0.25
0.10x0.25 = 0.025moles
Now that we have found the moles, we need to find the Mr so that we can calculate them to
find the mass.
Na2CO3
(23x2) + (12x1) + (16x3) = 106
Mass = Mr x moles
Mass = 0.025x106
Mass = 2.65g
Preparing the standard solution method:
We had worked out the mass no we had to make the required amount of sodium carbonate.
We had put a weighing boat on the balance and accurately put 2.65g of sodium carbonate.
Distilled water was used to clean of all the solution off the weighing boat so that there is none
left on it, we had poured it into a large beaker, where we had to dissolve all the sodium
carbonate using a stirring rod so that there were no bits of it left in it. A funnel was used to
pour the solution from the beaker into 250cm3 volumetric flask, keep pouring more distilled
water until the bottom of the meniscus touches the line using eye level so that the solution is
not above nor underneath the line. If it had gone above or underneath we would have to start
again and make the mass, we needed. A stopper had been placed on a volumetric flask so that
none of the solution was spilled. The flask would be inverted a few times so that all the
solution is spread out equally.
, Part 2:
Calibrating the pipette method:
The mass balance was already calibrated from part 1. A dry beaker was placed on the
balance. Using a glass pipette 25cm3 of water was transferred onto the dry beaker. The mass
of the water was recorded. To find the actual volume we used the formula:
volume of water = mass of water/density
The true value of water is 25cm3. We compared to see if it was within tolerance. If it was in
tolerance then we would use it, if not then we would have to repeat it again and replace it.
Calibrating the pipette calculations and result:
To calibrate the pipette, the balance had to be calibrated first. A dry beaker was placed on top
of it, and it would say 0. 25cm3 of water was transferred into a beaker and then I had recorded
the mass. My mass was 24.94g and the density of water is 0.9982. To find the volume I used
the formula:
Volume of water = mass of water/density of water
Volume of water = 24.94/0.9982
Volume of water = 24.98cm3
My result was intolerance so I wouldn’t have to repeat it again and my pipette is calibrated.
Setting up and performing the titration method.
When the pipette had been calibrated, 25cm3 of the sodium carbonate solution was
transferred into an 250cm3 conical flask, 2 drops of methyl orange indicator was added, and
we had swirled it, so the indicator was dissolved in the solution. Then we had to make sure
the burette was cleaned, once it was cleaned a funnel was used to pour hydrochloric acid until
it filled to 0, making sure the bottom of the meniscus touches the 0 line. Using the
hydrochloric acid, titrate the sodium carbonate solution, until you see a colour change occur.
Record the rough result first so then you get a rough idea of how the accurate results are
going to be around. The other 2 results were recorded accurately using eye level and drop by
drop so that we can see when the colour change had happened. Once the colour change
happened record both results down. Our rough result was 23, accurate was 23.4 and 23.4. so,
this means that our results are concordant, and we wouldn’t have to do another one. We need
to work the average by adding the 2 results and divide by 2.
23.4+23.4/2
46.8/2 = 23.4cm3
Results of titration including if results are concordant:
Rough: 23
Accurate: 1= 23.4, 2 = 23.4 (results are concordant)
Trial 1 2 Average
Volume 23.4 23.4 23.4
Calculations to determine the concentration of acid to 2dp:
To find the concentration we use the formula: concentration = moles/volume in dm3.
We first had to convert our average result into dm3 by dividing by 1000:
23.4/1000 = 0.0234
