In: Chemistry
How much heat is released when 28.0 g of lithium metal reacts as shown below? (Answer should come out to 448 kJ)
2 Li (s) + 2 H2O (ℓ) → 2 LiOH (s) + H2 (g) ΔHº = −222 kJ
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 222 kJ heat is released
2 x 6.94 g = 13.88 g 222 kJ heat is released
28 g ?
Then,
? = ( 28 g/ 13.88 g) x 222 kJ heat is released
= 448 kJ heat is released
Therefore,
448 kJ heat is released when 28.0 g of lithium metal reacts.