I then placed the white tile on the clamp, at the bottom. This is where the conical flask will be placed. I placed the conical flask right under the burette (the tap), and on the white tile. I then turned on the tap, to allow the sulphuric acid to run down through the pipette, (with the help of gravity) into the conical flask. The conical flask will be washed with distilled water beforehand. At first, you can allow large volumes of sulphuric acid to fall into the conical flask. I swirled the solution in the conical flask, every time droplets fell in. Slowly, you need to decrease the rate at which sulphuric acid is falling, because, it is reaching neutralization. I needed to make sure that I record exactly where neutralization occurs. The droplets should slow down and should be inserted very slowly, drop wise. Swirling the solution is very important, because we want to see the colour change over a single drop.
There will be a colour change from yellow to orange, to show that it has reached end point, and neutralization has occurred. One drop will cause it to turn orange, which is where neutralization occurs. Swirl constantly and add droplets of sulphuric acid, and once it turns orange, turn the tap off. Add distilled water into the conical flask-squirt it around the conical flask, to remove any sodium carbonate droplets stuck on the side of the conical flask. If the colour changes back to yellow, then neutralization hasn’t occurred. More small droplets of sulphuric acid needs to be added. If the colour stays the same (orange), then neutralization has occurred. Record the burette reading on the burette, showing the volume of sulphuric acid used up.
To calculate the titre, the initial burette reading is taken away from the second burette reading. I repeated the experiment (method of titration) many times, until I obtained 2 concordant results.
A dry run is needed to be done before the actual titration. You do the same method as above to do the titration.
Here is a diagram of my final set up:
Results Table:
Here is my results table for my dry run. This table will help me to determine the average titre:
I shall do a dry run, which is just a practice run through of the experiment. After that I shall start the actual experiment. My dry run may not be accurate, because it was my first time, and I may have made some mistakes. Do therefore, I shall learn from my mistakes in the dry run, and use my skills to carry out the experiment.
I shall be doing 5 repeats so I gain reliable data. The repetition shall show the reliability, and I shall stop doing the experiment, once I receive 2 concordant titres.
The glassware needs to be cleaned every time I do a repeat. I do this by washing the glassware, with the solution that is going to go in. for example, I shall wash the burette with sulphuric acid, because sulphuric acid shall go into the burette. I shall wash the bulb burette with sodium carbonate, because sodium carbonate will be going into the bulb burette. However, only small amounts of the solutions will be used to clean the equipment, because every drop of the solutions is important in the experiment.
References:
This web page helped to explain the indicator methyl orange. I was able to understand how methyl orange works, and the neutralization points. I also learnt the colour changes of methyl orange, and also found the structure of methyl orange. This web page also explained the indicators litmus red and Phenolphthalein. I was then able to understand why methyl orange was used for this experiment. methyl orange
This web page helps me to draw the titration graphs of acids and bases, when they have a certain strength/weakness. I was able to describe each graph, and give examples of reactions. I used the diagrams given in the web site of the four types of titration graphs.
This web page explained the solubility of sodium carbonate. I was able to understand the solubility of group 1 elements, such as sodium. I received information on carbonates too. I used this information to explain the decomposition of sodium carbonate, and what products can be formed if carbonates are burnt.
This web page helped to explain to me about corrosives. I was able to use this information to relate it to sulphuric acid. I used it for my risk assessment, where I was able to explain the risk assessment and reduction of sulphuric acid.
I obtained an image from this web page. I needed a picture of a titration set up, and this web page had exactly what I was looking for. I made some alterations after I copied the picture, but this picture showed exactly how my experiment was set up.
This website helped me to get a clearer picture of the colour changes of indicators which I could use, such as methyl orange, phenolphthalein, litmus red and bromothymol blue, which I will be explaining in my evaluation on page 21.
This website helped me to calculate the percentage error of my apparatus and experiment.
Analysis:
Here is my result table after I completed the titration process:
Average Titre: (28.2 + 28.2 + 28.2) / 3 = 28.2 cm³
The average titre is: 28.2ml. This is the average amount of sulphuric acid required to neutralize the sodium carbonate solution.
I repeated the experiment 5 times, (without the dry run), so I obtain reliable data. From my results I can see that my data was reliable, due to a particular value appearing 3 times as the titre (28.2).
Calculating the Concentration of Sulphuric Acid:
Proving the Concentration/Volume of Sodium Carbonate:
Relative molecular mass of 1 mole of sodium carbonate:
(23 x 2) + (12) + (16 x 3) = 106g
We want to obtain 0.1 mol dmˉ³ of sodium carbonate, therefore:
106 x 0.1 = 10.6g
We need 250 ml (250 / 1000 = 0.25 dm³):
10.6/4 = 2.65g (one litre contains 4 times 250 ml. Therefore, you divide it by 4)
2.65g is needed to make 250 ml of Na2 CO3 (0.25 dm³) with the concentration 0.1 mol dmˉ³.
Therefore, Na2 CO3 contains 0.025 moles, due to 2.65 g produces 0.1 mol dm³
(0.025 x 106 = 2.65 g)
…Concentration of Sodium Carbonate…:
Concentration = no. of moles / volume
Concentration = 0.025 moles / 0.25 dm³
Concentration = 0.1 mol dm³
Here is the balanced equation of the neutralization reaction between sulphuric acid and sodium carbonate:
1 : 1 ratio
Na2 CO3 (aq) + H2SO4 Na2SO4 (aq) + H2O (l) + CO2 (g)
0.25 : 0.25
25 ml 28.2 ml
- mol dm³
There is a ratio between the number of moles between sodium carbonate and sulphuric acid. It is a 1:1 ratio, therefore, the number of moles in sulphuric acid must be the same as sodium carbonate (0.25mol dm³).
25 ml of 0.1 mol dm³ of Na2 CO3 is neutralized by 28.2 ml of H2SO4. What is the concentration of sulphuric acid used?
Concentration of Sulphuric Acid:
Concentration = no. of moles / volume
Moles Volume
(mol dm³) (dm³)
Na2 CO3 0.0250 0.2500
H2SO4 0.0250 0.0282
Concentration = 0.0250 / 0.0282 = 0.8865 mol dm³
I have found out that 28.2 cm³ of sulphuric acid with the concentration of 0.8865 mol dm³, was needed to neutralise 25 ml of 0.025 mol dm³ of sodium carbonate.
