Question

CLASS 11 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:

C

Explanation:

mass of C2H6=90g

complete combustion equation:

C2H6+O2=CO2+H2O

Balancing equation:

2C2H6+7O2=4CO2+7H2O

Mr of C2H6=30

no of mole=mass/realtive molecular mass

No of moles of C2H6=90/30

no of mol=3

Mole Ratio:

C2H6. O2

2. :. 7

no mole. 3. x

no of mole of Oxygen=10.5

Mr of O2=32

mole=mass/Mr

10.5=mass/32

mass=32*10.5

mass=336

Answer 2

Given - Mass of C2H6 - 90 gram

Find - Mass of oxygen required for complete combustion of 90 g of C2H6.

Solution - The complete reaction of combustion of C2H6 is -

2C2H6 + 7O2 --> 4CO2 + 6H2O

Moles of C2H6 given = 90/30 = 3 moles.

2 moles of C2H6 require 7 moles of oxygen

3 moles of C2H6 will require oxygen = (7/2)*3 = 10.5 moles.

Mass of oxygen required = 10.5*32 = 336 gram.

Hence, mass of oxygen required for complete combustion of 90 g of C2H6 is (C) 336 g.