A student dried a wet crucible with a kimwipe. A piece of kimwipe was left clinging to the inside wall of the crucible. The student did not see the piece of kimwipe when adding the NaHCO3-KCl mixture to the crucible. The crucible and its contents were weighed and subjected to three heating cooling cycles.

Question

A student dried a wet crucible with a kimwipe. A piece of kimwipe was left clinging to the inside wall of the crucible. The student did not see the piece of kimwipe when adding the NaHCO3-KCl mixture to the crucible. The crucible and its contents were weighed and subjected to three heating cooling cycles.
Could this experimental error significantly affect the percentage of NaHCO3 in the mixture?
Justify your answer with an explanation.

DrBob222 · Answer

What were the heating/cooling cycles?

If heating was up to 100 to say 105 C, I don't think any error would be made because the piece of paper was weighed both before and after heating so any change in mass was not due to loss of the paper. If however, the temperature of at >150 C (I assume it was of the order of 250 C or do--probably changing NaHCO3 to Na2CO3 and I think that's about 270C) then the paper would be burned off. I doubt that the carbon left would be oxidized to CO2 so some carbon would remain BUT the loss in mass of the paper would add to the loss in mass due to the loss of CO2 from NaHCO3 and that would make the results for %NaHCO3 high.