Thinking hard about errors in titration

In summary, the conversation discusses potential errors in a titration experiment involving citric acid and NaOH. These errors include splashing of the citric acid, contamination in the burette, inaccurate readings, residual water in the burette, and imprecise measurements of the original solution. The group also mentions the importance of inverting the solution and potential errors related to bubbles and improper positioning of the titration nozzle. Additionally, they suggest checking for sample contamination and ensuring proper cleaning of the burette for accurate measurements.
  • #1
dagg3r
67
0
hi guys assistance in this area would be great just see what i have written and comment on them please thanks! all.


im thinking about the errors in titration from doing a typical acid-base titration to talk about in my experiment and these are the errors i came up with. First of all my class got a higher average titre required to titrate NaOH against citric acid so I am thinking why my titre + concentration of citric acid is low. These are what i came up with.

My experimental procedures were given 50ml of lemon juice, get 20ml into conical flask, dilute to 200ml with water, add ethanol near the end to get rid of bubbles, invert the solution 40 times. get 20ml aliquots from the dilute solution, titrate against NaOh and observe the end point turning to pink from the indicator.

* citric acid liquid was lost to splashing before the end point was reached.
* buret may have been contaminated with some other solution other than the one being tested.
* reading of the buret may have been off.
* distilled water remained in the buret before analysis
* maybe did not get exact 20ml from the 50ml original


My friends told me these notes below but i don't know what they mean someone care to explain:
* bubble appeared during titration in the tip of the buret. " the buret contained NaOH so what bubbles are they talking about?/ what error is that?"
* Titration nozzle was not flush with the mouth titration tube." no idea what they are talking here heh"

So can some one read the experimental procedures and determine some errors / add to my existing one/ tell me if my errors are wrong :p and btw what does the inverting do? and also how does it change ur results? and lucky last question does adding too much ethanol do anything to the results thanks!
 
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  • #2
You could always have my personal favourite: 'Substance X was not actually substance X'. But back to stuff you will want to use:

dagg3r said:
* bubble appeared during titration in the tip of the buret. " the buret contained NaOH so what bubbles are they talking about?/ what error is that?"
* Titration nozzle was not flush with the mouth titration tube." no idea what they are talking here heh"
I think these are when you are meant to run the burrette through with the substance to stop air bubbles making the experiment inaccurate.

Others errors can include the funnel (if used) being left in the burrette causing inaccuracies in the measurement from the burrette.

Hope this might help a bit.

The Bob (2004 ©)
 
  • #3
Other possible errors would be sample contamination, since you mentioned that your results were a little low. Could there be something else present in your sample other than citric acid?

The burette could be dirty, thus affecting volume measurements. Reading of burette should be to 2 decimal places approximation for higher accuracy. Burette should be washed thoroughly with distilled water and rinsed with the solvent you are going to fill the burette with to titrate. If there are droplets adhering onto the inner surface, it means that the burette is dirty.

Air bubbles at the tip would affect the volume of NaOH read from the burette. E.g. with the air bubbles, would it still be 20ml you're reading or less?

Was the stock sample well mixed before taking out 20ml aliquots?

Hope this helps! :smile:
 

1. What is titration and why is it important in scientific experiments?

Titration is a laboratory technique used to determine the concentration of a substance in a solution. It involves the gradual addition of a known solution (titrant) to a known volume of the solution being analyzed until an endpoint is reached. This helps scientists accurately measure the amount of a specific substance in a solution, which is crucial in experiments involving chemical reactions, quality control, and medical diagnostics.

2. What are some common sources of errors in titration?

Some common sources of errors in titration are human error, equipment error, and environmental factors. Human errors can include incorrect measurements, misreading the burette or flask, or not recording data accurately. Equipment errors can be caused by improperly calibrated instruments or leaky apparatus. Environmental factors, such as temperature and humidity, can also affect the accuracy of titration results.

3. How can we prevent or minimize errors in titration?

To prevent or minimize errors in titration, it is important to follow proper laboratory techniques and procedures. This includes calibrating equipment before use, using accurate measurements and recording data carefully. It is also important to control environmental factors, such as temperature and humidity, and to repeat experiments multiple times to ensure consistency in results.

4. What is the significance of understanding and analyzing errors in titration?

Understanding and analyzing errors in titration is crucial for ensuring the accuracy and reliability of experimental results. By identifying and addressing potential sources of errors, scientists can improve the precision and validity of their data. This is important for drawing accurate conclusions and making informed decisions based on the results of titration experiments.

5. How can we calculate the percentage error in a titration experiment?

The percentage error in titration can be calculated by taking the absolute value of the difference between the measured value and the true value, dividing it by the true value, and then multiplying by 100. This value can then be interpreted as the percentage difference or deviation from the true value. It is important to note that a small percentage error does not necessarily indicate a more accurate result, as systematic errors can result in consistently incorrect measurements.

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