a)
2 Li + Se ==> Li2Se
To balance the reaction we must have the same number of atoms on both sides of the reaction.
Answer a): 2 Li + Se ==> Li2Se
b) 2 Li + Se ==> Li2Se
25 g of Li react with Se, 75 g of Li2Se are formed.
We need the molar masses for Se and LiSe
For Se) 79 g/mol
Li2Se) 93 g/mol
79 g Se ---- 93 g Li2Se
X ---- 75 g Li2Se
X = 63.7 g Se
Answer b): 63.7 g Se
