20. When 0.560 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (H°f) of NaF(s)?
(A) 24.8 kJ/mol
(B) 570 kJ/mol
(C) –24.8 kJ/mol
(D) –570 kJ/mol

相關試題

相關試卷