22. The value of ∆H for the reaction below is -1107 kJ.
2 Ba(s)+ O2 (g)→2 BaO(s)
How many kJ of heat are released when 5.75 g of Ba(s) reacts with 21.0g oxygen gas to form barium oxide?
First you must determine which is the limiting reagent (LR).
mols Ba = grams/molar mass = 5.75/137 = about 0.042
mols O2 = 21.0/32 = about 0.66
So Ba is the LR is Ba.
The equation tells you that 2*137 = 274 g Ba produces 1107 kJ. You want to know how much heat will be produced when 5.75 g is used.
1107 x (5.75/274) = ? kJ = heat released. dH then is = -??