Re: combustion of alcahols (1 Viewer)

[Pyramid]

What would one say about validity? And how to improve it?

I was thinking:

--> soot formed at bottom of can shows that combustion is incomplete. Since the aim is to find molar heat of combustion, which by definition requires complete combustion --> INVALID?

To improve validity to this effect: fan air (ie. oxygen) toward wick so an excess of oxygen encourages complete combustion.

Is this a "valid" judgment and solution for validity?

 

[Trans4M]

i dont think so. I cant remember but didnt the syllabus dot point say something about temperature and pressure? If so then your experiment was carried out at room temperature and probably at at different pressure so not valid for that experiment.

i think wat your saying is more like reliability. Validity is like did you set out what you aimed to do. You did everything that was required.

 

[Ishynooshy]

Validity is a measure of how close your observations/quantitative results are to empirical data. Your experiment would only be invalid, if you are unable to come up with an explaination as to why your data does not match said empirical data. In effect, it is related to the accuracy and reliablity of the data obtained from your experiment.

In your case, the experiment is valid. There were factors such as the occurrence of incomplete combustion and loss of heat to the surrounding, which caused the calculated molar heat capacity of the alcohol to the lower than the correct value.