Question

1.0g of mg is burnt with 0.28g of o2 in a closed vessel, which ractant is left in excess n how much

Answer 1

Answer:

2Mg+O  

2

​  

→2MgO

∴1 mole of O  

2

​  

 reacts with 2 moles of Mg

∵ Moles of O  

2

​  

=  

32

0.28

​  

=0.00875

0.00875 mole of O  

2

​  

 reacts with  

1

2

​  

×0.00875 moles of Mg

=0.0715 Moles of Mg

Hence, mass of magnesium that reacts  =moles×molar mass

 

                                                                   =0.0715×24=0.42 g

That means, out of the 1 g of Mg, only 0.42 g is used.

Therefore magnesium is in excess  by (1−0.42)=0.58 g.

Hence, option B is correct.

Explanation: