chemistry cwk help

any ideas what i can mention for:

What were the main sources of error in the experiment?

this is for an investigation for the enthalpy of decomposition of sodium hydrogencarbonate.

thanks.

Reply 1

bono_3

ShOcKzZ

any ideas what i can mention for:

What were the main sources of error in the experiment?

this is for an investigation for the enthalpy of decomposition of sodium hydrogencarbonate.

thanks.

Come on someone, help Shockzz out. :mad:

Reply 2

MadNatSci

12

ShOcKzZ

any ideas what i can mention for:

What were the main sources of error in the experiment?

this is for an investigation for the enthalpy of decomposition of sodium hydrogencarbonate.

thanks.

You could mention loss of heat to the surroundings, assumptions in calculations (like the specific heat capacity is assumed not to vary with temperature, that sort of thing). Ummm... Limitations of the equipment used... Can't think of any more right now (just woke up!!) but tell me if that's the sort of thing you're looking for!

Reply 3

ShOcKzZ

OP

7

MadNatSci

You could mention loss of heat to the surroundings, assumptions in calculations (like the specific heat capacity is assumed not to vary with temperature, that sort of thing). Ummm... Limitations of the equipment used... Can't think of any more right now (just woke up!!) but tell me if that's the sort of thing you're looking for!

hey

thanks, that was exactly the sort of stuff i was looking for - heat lost to surroundings and limitations of equipment..but i was not too sure what you meant by SHC not varying? i thought it was just a fixed 4.18/4.2?

Reply 4

Barny

17

Also, not all of it may decompose? Just like enthalpy of combustion, not all of it is completely combusted. Im not sure though, this is just a guess.

Reply 5

xskater

6

If you did the experiment you probably did it in two steps:

by adding HCL to NaHCO3 and Na2CO3.

A source of error would be that the NaHCO3 and Na2CO3 did not fully react when it was added causing the results to vary. This could be used as another error but HEAT LOSS was the main error !

Hope this helps

Reply 6

MadNatSci

12

ShOcKzZ

hey

thanks, that was exactly the sort of stuff i was looking for - heat lost to surroundings and limitations of equipment..but i was not too sure what you meant by SHC not varying? i thought it was just a fixed 4.18/4.2?

It does vary a bit but even at degree level you tend to assume it doesn't... also you'd be assuming that the substances you're using have the specific heat capacity of water, which is maybe a better assumption to mention?

i don't know...

ShOcKzZ

any ideas what i can mention for:

What were the main sources of error in the experiment?

this is for an investigation for the enthalpy of decomposition of sodium hydrogencarbonate.

thanks.

we did this under timed conditions last week. I didn't do well on the number crunching, the hess cycle on that, kinda sad, as it was such an easy piece of coursework

Errors are the equipment, they arn't accurate, instead of using the measuring cylinder, you should use, the pippette filler and burette

Also weighing the solids, instead of weighing in a bottle, you should measure on a weighing boat.

chemistry cwk help

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