Did I Calculate the Enthalpy of MgO and HCl Correctly?

[Raza]

Using Hess's Law in 2 Questions

Hi, can someone just check my work and see if I did something wrong?
The answers seems strange.

And someone tell me where I can get the enthalpy values of molecules?

Thanks.

 

[Raza]

Please, can someone answer me?

 

[ksinclair13]

Looks good, but your second answer should have one more significant figure. Try looking for a table or appendix somewhere in your book to find the standard enthalpies of certain substances. Or you could check out this link:

http://www.psigate.ac.uk/newsite/reference/chemdata/3.html

 

[Raza]

Thank you very much, Ksinclair!