Question

Find mass of oxygen require for complete combustion of 90 g of C2H6?
(A) 136 g (B) 236 g
(C) 336 g (D) 436 g

Answer 1

Answer:

Option C

336 gram

Explanation:

Combustion of carbohydrates follows this eqtn:

CxHy + (x+y/4) O2 -------> xCO2 + y/2 H2O

x = no. of carbon

y= no. of hydrogen

here,

C2H6 + 7/2 O2 -------> 2CO2 + 3H2O

mass of 1 mol C2H6 = 2x 12+ 6x1

=24+6= 30 gram

for complete combustion of 1 mole C2H6 require 7/2 mol O2

in qstn, 90 g of C2H6 is given.so

number of moles= 90/30= 3 mol

3 mol C2H6 require 3x 7/2 mol O2

21/2 mol O2 is needed.

mass of 1 mol O2= 32 gram

mass of 21/2 mol O2= 21/2 x 32

= 21x 16

= 336 gram