heat of combustion questions??? (1 Viewer)

[Topher15]

i need to know:

Safety issues withthe heat of combustion prac
Explain the difference between the accepted literature values and your experimental values
Suggest some improvements you could make to make your experiment improve its accuracy and reliably
Explain the difference between reliability (reproducibility) and accuracy of an experiment? How would u assess the reliability of this experiment

 

[xiao1985]

you burn things ... burning = dangerous
also, you might use glasswares... glasswares = cut danger

lit value should usually be higher than exp result, majorly because energy lose to the surrounding

use insulators to insulate your expmt from surround to minimise heat loss, repeat expmt, use better equipment

...

 

[Forbidden.]

incomplete combustion of hydrocarbons will give off a different temperature to the complete combustion of hydrocarbons and it works.

 

[mmmk]

accuracy - how close the result is from the accepted value. it can be improved by avoiding measuremental errors
reliability - results are considered reliable if repeated measurements give the same value

 

[lunavixen]

a literature value is assumption of no heat loss under perfect labratory conditions.
experimental values should be self explanatory, it's what you get in the experiment. Accuracy errors are mostly measuremental, so using precise equipment, having the spirit burner going for the same time each time, accuracy is also dependant on the amount of combustion of the combustible liquid used, as forbidden said. to improve the reliability of the experiment, it should be repeated several times.

 

[misbahf]

i need to know:

Safety issues withthe heat of combustion prac
Explain the difference between the accepted literature values and your experimental values
Suggest some improvements you could make to make your experiment improve its accuracy and reliably
Explain the difference between reliability (reproducibility) and accuracy of an experiment? How would u assess the reliability of this experiment

Safety issues:

1. Basic stuff: hair tied back. enclosed shoes, sfaety goggles....self explnatory stuff
2. We used methanol, ethanol and propanol.
3. Methanol is toxic: avoid skin contact
4. Meth: toxic by inhalation and if swallowed, irritant to eyes and skin
5. Same goes for the other two alkanols
6. all are highly flammable: keep a extingusher at hand

Experiemtal values:

1. this experiment is prone to an error of about 53%
2. Due to : HEAT LOSS! --> HUUUge factor. Heat is lost to the external environment through numerous ways (i.e. heating up the air molecules surrounding the flame)

Improvements:

1. COntrolled atmosphere (vacum?)
2. Data loggers to measure temp etc.
3. testing more alkanols
4. repeating tests for each alkanol and getting averages of the results

Reliability/accuracy:

1. You could repaet the same test using crappy equipment and a bad method and get the same results but if you use precise equipment, keep all your variables the same. and use a good method you could do the experiment once and get more valid results.

Hope i've helped. Good luck with whatever you need this for!
Take care.