[Lather]

Hey guys, I'm hoping for help with an assignment I have.

We conducted a lab experiment to find the enthalpy of decomposition for sodium hydrogencarbonate using Hess's law.

I have a question that asks 'Why did you find the enthalpy change indirectly?'. Well.. I'm really not sure.. As far as I know sodium hydrogen carbonate is baking soda, and we regularly heat it to the level it needs to decompose in our ovens, so I can't imagine why we couldn;t just do it directly.

Maybe it's worth mention that we were originally meant to be using potassium hydrogencarbonate, but we run out so myself and others had to use sodium hydrogencarbonate instead. Does this make a big difference?

Also, I've been researching enthalpy level diagrams, and I think I just about understand them, but I don't get how I'm meant to fit 3 different chemical equations on one?

Reaction A: K2CO3 + 2HCl    2KCl + CO2 + H2O
Reaction B: KHCO3 + HCl    KCl + CO2 + H2O
Reaction C: 2KHCO3    K2CO3+ CO2 + H2O
(Using A and B to find C)

[mjc123]

I have a question that asks 'Why did you find the enthalpy change indirectly?'. Well.. I'm really not sure.. As far as I know sodium hydrogen carbonate is baking soda, and we regularly heat it to the level it needs to decompose in our ovens, so I can't imagine why we couldn;t just do it directly.

What is the difference between reactions A and B and reaction C in how they are physically carried out?
How did you measure the enthalpy change for A and B?
How do you think you would measure the enthalpy change for C? Would it be easy?

[Lather]

Well with A + B we measured the temperature of the HCL before, and then the temperature of the solution afterwards to get our ΔT. Then we used (mcΔT)/n to find the ΔH. The only issue with doing this to directly find C is that mixing HCL and NaHCO^3- would potentially be dangerous, but then why couldn't we just do it with water?

[Lather]

I have a question that asks 'Why did you find the enthalpy change indirectly?'. Well.. I'm really not sure.. As far as I know sodium hydrogen carbonate is baking soda, and we regularly heat it to the level it needs to decompose in our ovens, so I can't imagine why we couldn;t just do it directly.

What is the difference between reactions A and B and reaction C in how they are physically carried out?
How did you measure the enthalpy change for A and B?
How do you think you would measure the enthalpy change for C? Would it be easy?

Sorry, just quoting you so you'll get a notification I've replied. Forgot to in my above post.