I have gone into great detail in my Phenolphthalein and Methyl Orange Titration Analysis essay to explain the analyses of the results I have obtained and whether or not they are consistent. I have also done calculations, which are checked and correct for the titration I did on the two being tested....
- Pipette and pipette filler
- Methyl orange and Phenolphthalein indicator.
- 50 cm3 Burette and burette stand
- conical flask
- Goggles and lab coat
- 25 cm3 measuring cylinder
- Glass rod
- Sodium carbonate
- Distilled water
- 100cm3 beaker
- Funnel
Method for titration
1- Use a pipette and pipette filler to add 25 cm3 of sodium carbonate to a clean conical flask.
2- We add 3 drops of a phenolphthalein indicator to the conical flask. The solution should go
purple
3- Fill the burette with an abit of HCL to clean the burette because water would concentrate the
acid.
4- Fill the burette with HCL once it has been fully cleansed to the top, 50cm3
5- Slowly add the acid from the burette to the conical flask, swirling to mix.
6- The color should go from purple to colorless.
7- We record the endpoint of the phenolphthalein when the solution turns clear. We may need to
resort to one drop at a time so we can get more precise results as we get then clearly identify
when the solution goes clear.
8- We know need to get a pink solution, so we do this by adding 3 drops of the methyl orange
indicator to the conical flask containing the phenolphthalein and HCL. One we add the methyl
orange indicator to the solution the conical flask will go from clear to bright orange.
9- We Stop adding the acid when the endpoint is reached (when the color first permanently
changes). Note the final volume reading.
10-Repeat this section until three results are concordant. Ideally these should lie within 0.40 cm3 of
each other.
11-We calculate the Titre volume(cm3) by subtracting the start volume (generally 0.00cm3) from
the end volume for phenolphthalein. And then for methyl orange the start volume, which is
different as either the burette was filled to the top (0.00 cm3) or where the phenolphthalein
titration finished. We then calculated its Titre volume from this result. The results are
concordant if there is a 0.40cm3 difference between them.
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,Abbas Nadeem Unit 2 Assignment A
Making the standard solution for titrations:
1- Weigh out between 1.2g and 1.4g of sodium carbonate using a weighing boat and record the
mass
2- Pour the weighed sodium carbonate into a beaker
3- Weigh the weighing boat without any powder on it. Record the mass
4- Add a small amount of distilled water to the beaker and stir using the glass rod.
5- Repeat step 4 until the powder completely dissolves
6- Using the glass funnel pour the mixture into the 250cm3 volumetric flask
7- rinse the beaker and rod into the funnel using distil water.
8- Using distil water fill the volumetric flask to the line, carefully ensuring the bottom of the
meniscus is touching it at eye level, you can use a dropper for this step.
9- Once the meniscus is at the correct level, stop the flask and invert 10 times.
Colorimetry
Equipment -
- Goggles and lab coat
- Distilled water
- Hydrated copper sulfate
- Colorimeter
- Funnel
- Balance
- Unknown samples A and B
Method for colorimetry
1- Choose the wavelength of light that will be used in the colorimetric analysis.
2- Prepare a set of known-concentration of stock solutions.
3- Reference the colorimeter using water
4- Using the colorimeter, determine the absorbance of each stock solution.
5- On a graph, plot the absorbance vs. concentration for each stock solution
6- Draw a best-fit line through the data points.
7- Using the colorimeter, determine the absorbance of a solution of unknown concentration.
8- Calculate the concentration of this solution using the calibration curve.
Making the stock solution for colorimetry:
1. Calibrate the weighing balance that you will be using.
2. Weigh 2.50g of hydrated copper (II) sulfate (CuSO4.5H2O).
3. Carefully transfer the hydrated copper(ll) sulfate to a beaker, accurately and precisely recording
measurements to determine the exact mass transferred.
2 of 23
, Abbas Nadeem Unit 2 Assignment A
4. Add 25cm3 of hot distilled water to the beaker, stir and completely dissolve the hydrated copper (II)
sulfate.
5. Carefully and accurately transfer all the solution to a 100cm3 volumetric flask and make up the
solution to 100cm3 with more distilled water.
6. You have made a stock copper (II) sulfate solution of approximately 0.1M.
We used some of the stock copper (II) sulfate solution to make 4 smaller dilutions. The original
concentration of the stock solution was 0.1M and we had to make a solution with 0.08, 0.06, 0.04,0.02
from the 0.1M solution. We did this by using v1 x c1 = v2 x c2
We used 680 wavelengths as it gave us the best readings. We tested this by placing the standard
solution in the colorimetry and checking the absorption for each wavelength, we then came to conclude
that 680 provided the most accurate results.
Equipment -
- Goggles and lab coat
- Hydrated copper sulfate
- Distilled water
- Colorimeter
- Cuvettes
- Funnel
- Balance
- Unknown sample A and B
Start 0.30 4.50 0.00 0.00 0.00 0.00
volume
(cm3)
Titre 22.20 16.60 16.70 16.05 16.85 17.25
volume
(cm3)
Concordant No Yes Yes No Yes No
?
3 of 23
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