Question

When 8 moles of lithium metal react with excess oxygen gas, how many moles of lithium oxide can be produced? 4Li + O2 → 2Li2O

Answer 1

Answer: Option (b) is the correct answer.

Explanation:

The given reaction is as follows.

        $4Li + O_{2} \rightarrow 2Li_{2}O$

Also, it is given that 8 moles of lithium metal on reaction with excess of oxygen results in the formation of lithium oxide.

Let the number of moles of lithium oxide is x. 4 lithium atoms give 2 atoms of lithium oxide, therefore, divide the number of moles of lithium by half as follows.

   Number of moles of lithium = number of moles of lithium oxide

                                               8 = 2x

 or,                                         x = $\frac{8}{2}$

                                              x = 4

Thus, we can conclude that when 8 moles of lithium metal react with excess oxygen gas, then 4 moles of lithium oxide can be produced.

Answer 2

4li + o2 ----> 2li2o
8      x

cross multiply 8x2 ÷ 4x 
                       x=4 
  
 the answer is 4