ΔHº = −ve = exothermic reaction = heat will be released
Molar mass of Li = 6.94 g/mol
2 Li (s) + 2 H2O (ℓ) → 2 LiOH (s) + H2
(g)       ΔHº = −222 kJ
2
mol                                                         Â
222 kJ heat is released
2 x 6.94 g = 13.88
g                                    Â
222 kJ heat is released
28
g                                                                      Â
?
Then,
                   Â
? = ( 28 g/ 13.88 g) x 222 kJ heat is released
                      Â
= 448 kJ heat is released
Therefore,
448 kJ heat is released when 28.0 g of lithium metal reacts.
