Chem IA literature value

[xx_jellybeanz_xx]

I'm doing my practice energetics chemistry IA on the reaction between HCl and Sodium Carbonate. I can't seem to find the literature value to compare to for my percentage error...does anyone have a good source i could start looking at?

[IBelieveInUtopia]

Although I am not sure, but you could find the literature value using the delta H of formation.

[Tilia]

What exactly are you finding? The enthalpy change?

Anyway, the CRC Handbook of Physics and Chemistry usually contains all information you need.

[xx_jellybeanz_xx]

What exactly are you finding? The enthalpy change?

Anyway, the CRC Handbook of Physics and Chemistry usually contains all information you need.

Yeah I'm looking for the enthalpy change of the reaction

[Dzeb]

I suppose you're using the calorimeter to measure the enthalpy change. You can 'calibrate' your calorimeter. Mix 50ml of hot and 50ml of cold water (measure the temperatures). Then there will be three heat measures:

Hot water losing heat

Cold water receiving heat

Calorimeter receiving heat.

The sum of all three must be equal to 0 (1st law of thermodynamics - energy can not disappear nor be created). Thus, you will get the specific heat of the calorimeter. Add it to your calculations and your experiment will be very precise =]

[x___x]

You can use the bond enthalpies in order to get the enthalpy change value. This can be used to substitute the literature value, if you couldn't find it.

2H-Cl + Na2-CO3 --> 2NaCl + H2O + CO2

you have to subtract the sum of the bond enthalpies of the products from the sum of the bond enthalpies of the reactants.

now, the following data (average bond enthalpies) are taken from the IB Chemistry data booklet:

H-Cl: 431 KJ/mol

C=O: 743 KJ/mol

C-O: 360 KJ/mol

O-H: 463 KJ/mol

note that covalent compounds only have bond enthalpies.

The concept is correct, but i'm not quite sure whether it applies to this case, since the reaction includes ionic compound. So please ask your teacher before you actually do the calculations. If she/he said that the concept can be applied, then do please tell me so that i can help you with the calculations, if you have any problem or doubts.

[Tilia]

It works for ionic compounds, it's just bond enthalpies that only apply to covalent in gaseous state. So the calculation above ought to be correct.

[Daedalus]

I can't find any literature values either online, sorry. Either you will have to look it up in some massive lexicon-like book or you should just omit it altogether. The reason for this is that the average bond enthalpies are average bond enthalpies. When you calculate the enthalpy change of a reaction in that way you can end up with answers very different from the actual answer. You might have a 8% error from your experimental data to your calculation, but your calculation could have a 23% uncertainty itself...

(i deleted this for a bit because i wasn't sure this was right but i checked and i think its right)

edit: maybe 23% is excessive. i'm not sure how much it can vary though.. but i still think it might be too inaccurate to be useful

Edited December 9, 2010 by Daedalus

[Tilia]

I can't find any literature values either online, sorry. Either you will have to look it up in some massive lexicon-like book or you should just omit it altogether. The reason for this is that the average bond enthalpies are average bond enthalpies. When you calculate the enthalpy change of a reaction in that way you can end up with answers very different from the actual answer. You might have a 8% error from your experimental data to your calculation, but your calculation could have a 23% uncertainty itself...

(i deleted this for a bit because i wasn't sure this was right but i checked and i think its right)

edit: maybe 23% is excessive. i'm not sure how much it can vary though.. but i still think it might be too inaccurate to be useful

You're quite right, but it can be done using enthalpy change of formation, which still gives an uncertainty, but a much lower one.