how much energy is released during the reaction of 2.5l diboron hexahydride with 5.65l chlorine gas?

Answer 1

Do you have an equation?
B2H6 + 6Cl2 ==> 2BCl3 + 6HCl

Convert 2.5 L B2H6 to mols
Do the same for 5.65 L Cl2.
These are gases. What's the pressure? the T?

Determine which is the limiting reagent.

See if this will help you.
https://socratic.org/questions/according-to-the-following-reaction-how-much-energy-is-evolved-during-the-reacti