Calculating Heat Released in Ba(s) + O2(g) → 2BaO(s) Reaction

[geffman1]

The value of H° for the reaction below is -1107 kJ:
2Ba(s) + O2(g) --> 2BaO(s)

How many kJ of heat are released when 5.75 g of Ba(s) reacts completely with oxygen fo form BaO(s)?


i worked out the moles of Ba which was 0.0412 then times by -1107 whcih is 46.4 however the answer is 23.2, i don't understand why becasue the is a 2 to 2 relationship between Ba and BaO? any help would be good

Homework Equations

The Attempt at a Solution

 

[bucher]

The specific enthalpy of reaction would be -1107 kJ per 2 moles of Ba consumed (or per mole of oxygen consumed or per 2 moles of BaO produced). This would give the 23.2 kJ of heat released.

 

[geffman1]

thanks, but how do u no you have to use the coeffecient of the oxygen, when the Ba is limiting?

 

[Borek]

Value is given not per mole of Ba, but per so called 'mole of reaction'.

That's not always the case.