Use heats of formation data bellow to calculate ΔH° for the reaction:?
Use heats of formation data bellow to calculate ΔH° for the reaction:
Ca(OH)2 (s) + H2SO4 (l) → CaSO4 (s) + 2H2O (l).
ΔH°f(Ca(OH)2 (s)) = -986.59 kJ/mol
ΔH°f(2H2O (l)) = -285.9 kJ/mol
ΔH°f(H2SO4 (l)) = -811.32 kJ/mol
ΔH°f(CaSO4 (s)) = -1432.7 kJ/mol
I tried answering this both with the information provided (and got +79.31) and with the correct H2O heat of formation (-285.9/1mol, therefore -571.8 for 2H20) and got -206.6, both of my answers the homework website said were wrong but I don't get why. Anybody know?
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Answers & Comments
Your -206.6 kJ answer should be correct. Does the website require units, or simply a numerical answer? You've used the correct number of significant figures, but you might try entering -206.59 kJ and see if it likes that better.