Question

12. When 120g of carbon is completely burnt in the presence of oxygen at 0°C and I atm
then find the mass of O2 required in kg.
b) 0.320
c) 3.2
d) 0.0320
​

Answer 1

Explanation:

Correct option is

A

27.49g

Given, C+O

2

⟶CO

2

;ΔH=−94.05kcal

C+

2

1

O

2

⟶CO;ΔH=−26.41kcal

Let a mole of carbon reacts to form CO

2

and b mole of carbon reacts to form CO.

Since, only 12 g carbon; i.e., 1 mole is used up, thus,

a+b=

12

12

=1 ...(i)

Also, a×94.05+b×26.41=75 ...(ii)a=0.718,i.e.,moleofCO

2

formed

b=0.282,i.e.,moleofCOformed

Also,moleofO

2

usedforthischange=0.718+

2

0.282

=0.859

Thus,massofO

2

used=0.859×32=27.49g