-Ingestion will cause severe corrosion of and damage to the gastro-intestinal tract. In this case, do not induce vomiting, wash out mouth and drink water or milk. Seek medical attention immediately.
-Inhalation could in the most severe case, cause pulmonary edema. In this case, transport immediately to hospital.
-Although, with using between 0.05M and 0.15 of sulphuric acid:
-Eye protection should be worn
-The room should be adequately ventilated.
-Avoid inhalation
-Take care pouring solutions; hand protection should be worn if necessary.
-When diluting, always add acid to water, not water to acid.
Methyl Orange Solution is stable but toxic to the eye, skin and is a respiratory irritant.
Therefore safety glasses should be worn and should avoid inhaling dust.
Sodium Carbonate causes eye irritation and prolonged or repeated contact may cause skin irritation. If it is inhaled it may be irritating to the nose, throat and respiratory tract.
Swallowing the Sodium Carbonate may cause burns to the mouth, throat oesophagus and stomach, it may cause nausea.
Therefore wear appropriate clothing and devices when handling. Avoid breathing dust and avoid contact with eyes and clothing. Wash thoroughly after handling.
Why the plan will work
The plan devised for the titration needs to be accurate to produce precise and reliable results.
A titration is a method of quantitative analysis, which can be used when two solutions react together. Recording correct results and measurements are essential to work out the exact concentration of the Sulphuric Acid used.
When involved in a titration there are errors or uncertainties related to the precision of the equipment used. Therefore with the use of small-scaled pipettes, pipette fillers and burettes, precision is better and less errors will be caused. By using these precise instruments, measurements of the two solutions will be more accurate, therefore creating a more accurate and reliable result.
With the knowledge that the equipment will cause a slight measurement error, taking readings from the burette and pipette should be smaller and so more accurate. For a burette, each drop had a volume of 0.05cm3; therefore, if the readings were taken to two decimal places the percentage error would be less then 0.4%. For this experiment.
For pipettes, because the end retains the last drop of solution there is a percentage error of 0.24%.
However, I will cancel out these errors and make my plan more precise by washing out the burette, pipette and my conical flask with appropriate solutions. For the burette I will wash it out with sulphuric acid and the conical flask with the sodium carbonate solution therefore getting rid of any unwanted substances that may alter the final result.
To be more accurate, I will add drop by drop of Sodium Carbonate solution into the conical flask with swirling after every addition, otherwise the end point will be missed and the results will be inaccurate.
After filling the burette with the Sodium Carbonate solution I will remove the funnel so therefore during the titration, no excess Sodium Carbonate solution will interfere with the experiment. Which could alter the accuracy of the results and make them unreliable, therefore creating anomalous results.
By working out the correct amount of Sodium Carbonate to be used in the solution, I can provide the optimum relationship between the solutions. Therefore the titration will be more reliable due to one mole of the Sodium Carbonate reacting with the one mole of Sulphuric Acid.
I will repeat the titration until I get three volumes which agree to within 0.1cm3, therefore cancelling out any anomalous results due to inaccuracy.
With all these measures, my plan should be more accurate and therefore produce more precise results.
Analysis
Results
Average Titre = 23.6 + 23.6 / 2
Average Titre = 23.6
Concentration of Sodium Carbonate
Concentration = Number of Moles / Volume
- To work out the concentration of Sodium Carbonate, the number of moles is needed.
Number of Moles of Sodium Carbonate = Mass / Molar Mass
- After weighing the weighing bottle and anhydrous Sodium Carbonate, then weighing the bottle on its own, the mass of the anhydrous Sodium carbonate can be worked out.
Initial weight of bottle and contents = 16.6618 g
Weight of bottle and lid alone = 13.9823 g
Weight of just contents = Weight of bottle and contents – weight of bottle and lid
= 16.6618 – 13.9823
= 2.6795 g
Molar mass of Sodium Carbonate = 106 g
Therefore: Number of Moles of Sodium Carbonate used = 2.6795 / 106
Number of moles = 0.025278301
Volume of Solution = 250 cm3 (inside volumetric flask)
Therefore: Concentration of Sodium Carbonate solution = 0.025278301 / 250
Concentration of Sodium Carbonate solution = 1.011 x 10-4
x 1000 = 0.101 mol dm-3 to 3sf
Therefore, concentration of Sodium Carbonate solution = 0.101m
Concentration of Sulphuric Acid
Number of Moles = volume of acid x concentration / 1000
- Dividing by 1000 converts the units into decimetres.
- As stated in the plan, the reaction between the Sodium carbonate solution and the Sulphuric Acid is a one to one relationship ( 1:1 ) meaning that one mole of Sodium Carbonate reacts with one mole of Sulphuric Acid. By calculating the number of moles of the Sodium Carbonate, due to the relationship the number of moles of Sulphuric Acid is therefore the same.
Number of moles of Sodium carbonate in 25 cm3 = 0.101 / 1000 x 25
= 2.525 x 10-3
- So therefore the number of moles of Sulphuric Acid in 23.6 cm3 = 2.525 x 10-3
- The average titre = 23.6 cm3
- The average titre in decimetres = 23.6 x 10-3
- Substitute the values worked out into the formula.
2.525 x 10-3 moles = 23.6 x 10-3 x concentration
- Rearrange to find concentration of the Sulphuric Acid.
Concentration of Sulphuric Acid = 2.525 x 10-3 / 23.6 x 10-3
= 0.106991525
Concentration of Sulphuric Acid = 0.107 mol dm-3 to 3sf
Evaluation
By observing and comparing the information displayed in the table, it is clearly identifiable that there was one anomalous result. The first titration of the experiment was recorded at 24.2 cm3, in comparison to the other results, although it isn’t vast, the difference is still apparent, with the other two titrations at 23.6 cm3.
These other two titrations were recorded at the same volume, therefore the average of the titrations was 23.6 cm3, which is 0.6 cm3 different to the first titration. Clearing identifying that it was an anomalous result.
However, a reason for the anomalous result is the fact that it was the first titration and therefore a ‘rough’ one. With the use of this rough titration the other two titrations were made more accurate, as the end point region was then known.
Although one result was anomalous, the other two were accurate as both had the same volume and therefore the experiment can be called fairly precise and therefore creating reliable and accurate results.
However, with taking the anomalous result and other factors into consideration, it shows that the experiment was not completely precise.
One main area of concern which would make the experiment less accurate is the factor of measurements.
Errors or uncertainties related to the precision of the equipment used need to be identified to therefore indicate if the titration result was accurate.
The equipment used in the experiment for measuring, was the burette and the pipette. By calculating the percentage error of each piece of equipment will give a maximum and minimum value, which could have been obtained from the experiment.
Burette Error %: 0.05 x 100 / Average Titre
= 0.05 x 100 / 23.6
= + or – 0.21 %
-Although, because during the experiment, an initial and final reading of the burette was taken, this figure needs to be doubled.
0.21 x 2 = + or – 0.42
Therefore, burette error % = + or – 0.42 %
Pipette Error % : Tolerance x 100 / size of pipette. When tolerance = 0.06 cm3
When pipette size = 25 cm3
= 0.06 x 100 / 25
= + or – 0.24 %
Therefore, pipette error % = + or – 0.24 %
- By adding all errors, an overall percentage error for the experiment can be obtained.
- Overall percentage error = + or – 0.66 %
Therefore, to work out the maximum and minimum values that could have been obtained from the titration:
0.66 % of 23.6 = 0.0066 x 23.6 = + or – 0.15576
Minimum Value = 23.6 - 0.15576 = 23.44424
Maximum Value = 23.6 + 0.15576 = 23.75576
Therefore the range for an accurate titration is between 23.44424 cm3 and 23.75576 cm3. So, achieving a result between this scale is accurate. The result which was achieved in the experiment was 23.6 cm3 and the method used was therefore precise and reliable.
The size of the errors is quite significant and therefore had some impact on the titration. This error percentage is extremely important, as it cancels out the error by producing a maximum and minimum value.
The possible sources which inflicted error on the experiment were, during the experiment if the funnel used for pouring the Sulphuric Acid was left in the top of the burette, this would have affected the results if excess Sulphuric Acid had dropped into the burette, causing an incorrect titre reading. Also, the reading of the burette caused difficulty, to read the exact volume and also if excess acid had dropped in, then this would have affected the reading, which would affect the calculations.
Carelessness of apparatus would have caused errors, not rinsing out the pipette with distilled water before the experiment, if a substance was left in the equipment then the final reading would be affected. The measuring of the solutions using the equipment also caused errors, however, these were cancelled out by working out a possible range of results that could have been obtained. After taking into consideration the errors, the experiment procedure and the calculations of the molarity, I can say that the experiment was accurate and therefore it produced reliable results.
By working out the maximum and minimum values that cancel out the errors from measurements, it shows that the final result is fairly accurate. By following all procedures with exact precision, the experiment produced a reliable titration.
The procedure might have been improved with more precision in every step of the experiment. If the equipment used for measuring had a larger scale and a lower volume capacity, the reading from off of this would have been more precise because fewer mistakes would have been made. Due to the fact that if too much or too little of a solution was used due to incorrect reading from the equipment then the incorrect volume from the titration would have affected the overall results. Therefore using equipment with larger more visible scales would have improved the experiment.
By repeating the initial ‘rough’ titration several times would have made the results more reliable, identifying anomalous results. This aspect was used in the procedure and contributed to producing accurate results; it is an important stage in gaining more reliable results. Another possible improvement would be to add more drops of the indicator solution into the conical flask. By doing this the colour in the conical flask would have been stronger and the colour change, due to the titration would have been made more apparent and easier to identify the exact turning point. This would have given more reliable titration volumes and producing more accurate results. If the burette was positioned exactly vertical during the procedure then it would have been easier to read measurements and the exact amount of Sulphuric Acid would have been used, whereas if the burette was slanted then drops of acid would have clung to the side of the burette due to adhesive properties, and so the titration reading would have been incorrect.
By rinsing all of the equipment thoroughly with distilled water after every titration, then the exact quantities required would have been used. This would produce more reliable results due to it being more accurate.
If more care was taken during the procedure then the results would have been more reliable. By titrating drop by drop towards the turning point of the experiment, the exact moment of colour change would have been identified. Whilst titrating, rinsing the neck of the conical flask washed all the particles of the acid that were on the side into the reaction, helping to achieve accurate results during the experiment because all intended acid was used. By swirling the conical flask during the titration, the solution was agitated and so all particles were evenly distributed. This helped to make the experiment more accurate.
When reading the value from a burette, if a piece of paper is held behind the burette then it stops the light from interfering with the reading off of it. This makes it easier to read exact measurements. The procedures during the experiment that were necessary to ensure that the results were accurate, were, repeating the titration, by rinsing out the conical flask and using fresh amounts of Sodium carbonate solution after every titration. This would have cancelled out the possibility of error if some of the solution remained in the conical flask. By finding maximum and minimum values it shows how reliable the measurements were. This is key in gaining accurate results.
These factors were essential in producing results that are accurate and reliable.
Methods that would improve the experiment, all increase the accuracy and reliability of the titration if it was done again.
