Question

0.7 mol of metal M reacts completely with excess of fluorine to form 45 g of MF₂, how many moles of F are present in it. 

•  1.4 moles 
•  2.4 moles 
•  2 moles 
• 1.2 moles 

Answer 1

Using conceptual stoichiometry : 

Appling POAC on metal

\(\because \) 1 mole of metal formed one mole Mf₂ molecule

 \(\therefore\) 0.7 mole of metal formed = 0.7 mole Mf₂ molecule

\(\because \) Each molecule of Mf₂ contain = 2 f atom 

\(\therefore\) 0.7 mole of Mf₂ molecule contain = 2 x 0.7 moles of f atom

= 1.4 mole of f atom

Hence, 45 g of Mf₂ molecule contain 1.4 moles ' f ' atom.