Titration - sources of error (1 Viewer)

[with-chu]

What are some sources of error in the extremely accurate quantitative analysis of titration?

Other than incompetency please ><"


Also, what's the difference between reliability and accuracy? How do you relate these terms to titration?


Thanks! Any help appreciated

 

[ibbi00]

What are some sources of error in the extremely accurate quantitative analysis of titration?

Other than incompetency please ><"


Also, what's the difference between reliability and accuracy? How do you relate these terms to titration?


Thanks! Any help appreciated

Well there incompetency to start with. /jks.

I can tell you how to improve accuracy.

- Rinse the burette with the solution about to be added in order to reduce risk of contamination.
- Read measurements from the bottom of the meniscus. Especially when preparing the standard solution.
- Don't round off till the end whilst doing the calculations.

Reliability refers to the constancy of your results. i.e when you repeat the titration (3 times not including your rough) you get very close titre values that also agree with classmates' results.

Accuracy is the 'closeness' of the obtained results to accepted or typical results. I.e, Does the concentration of the unknown solution match with your results

Hope this helps

 

[js992]

• Indicator itself may be slightly acidic and can affect results especially if too much is used.
• Using a white card to sharpen the meniscus when reading it, improves reliability
• Using a pH meter and data logger increases accuracy
• To improve reliability, repeat titration until 3 concordant values are achieved (within 0.1mL of each other) and take an average
• Air bubbles in burette/pipette are another source of error

 

[with-chu]

thanks to both of you!

about the air bubbles in the burette and pipette, aren't they built to count for those bubbles?

 

[nat_doc]

thanks to both of you!

about the air bubbles in the burette and pipette, aren't they built to count for those bubbles?

the pipette can;'t control how many bubbles are present or even the volume of the bubble in the pipe. it does however, take into account that little bit that is stuck inside of it.

also, wiping down the pipette from any extra acid/ base that is on the outside due to you dipping it in the beaker makes sure that u have only exactly 12 mLs

 

[js992]

thanks to both of you!

about the air bubbles in the burette and pipette, aren't they built to count for those bubbles?

Nah. When you perform a titration you must ensure there are 0 air bubbles yourself. The pipette is only calibrated to ensure that 25ml is delivered whilst that last drop remains, hence the reason you never blow out the last drop.