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Urgent! Need some help figuring out uncertainties for my IA please!

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Hi everyone, this IA which involves me figuring out the following uncertainties is due tomorrow, but I'm not sure how to do it correctly, I'd really appreciate some help. So here it is:


We were diluting 3.0M HCl to various concentrations for a reaction with magnesium ribbon. Our method is terrible I know that, but what I need help with is figuring out my uncertainties.


The steps taken to dilute 3.0M HCl to 0.5M were this:


  • With a pipette (uncertainty of ±0.3mL), 3mL of 3.0M HCl was put, with one squirt, into a test tube.
  • Then, to dilute it to 0.5M, we put 15mL of water into the same test tube (which took 5 squirts, pipette with the same uncertainty).
  • We shook the test tube a bit to mix them up and then removed enough of this new solution to leave 3mL of now 0.5M HCl in the test tube. It took 5 squirts (not sure what the term is for squirt) of the pipette to remove enough solution to only leave 3mL of 0.5M HCl in the test tube. 

The issue: I have no idea what the uncertainty for the concentration of HCl is.


We did not use measuring cylinders at all, and the test tube where the dilution took place did not have any measurements on it. Our measurements of volume rely entirely on the pipette. I need to calculate the percentage uncertainty for this 3.0mL of 0.5M HCl, but I am completely lost. If someone could help me I would highly appreciate it. I didn't mean to leave this until the night before, I thought I did not have to consider the concentration of HCl's uncertainty, but now it seems I do. 

Thanks again!



Solved the issue myself never mind haha. If anyone else is stuck on similar questions, this website really helped me. http://lawrencekok.blogspot.com.au/p/ib-chemistry.html 

Edited by thedudeo

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