Question

volume of co2 liberated at STP on the complete combustion of 7.8g of benzene in presence of oxygen is

Answer 1

Chemical combustion equation for Benzene:

2C₆H₆ + O₂  ------> 12Co₂ + 6H₂O

The molar mass of Benzene is :

12 × 6 + 6 = 78 g /mol

moles of Benzene :

7.8/78 = 0.1 moles

Molar ratio of benzene to Carbon (iv) oxide liberated is :

2 : 6 = 1 : 3

moles of Co₂ is thus ;

0.1 × 3 = 0.3 moles

molar gas volume at stp is :

1 mole = 22400 cm³

0.3 × 22400 = 6720 cm³

Answer 2

Given:

STP

Complete combustion of 7.8g of benzene

Presence of oxygen

To find:

The volume of Co2 liberated

Solution:

The reaction takes place as,

2C₆H₆ + O₂  -> 12Co₂ + 6H₂O

Benzene + oxygen -> Carbon dioxide + water

To find the molar mass of Benzene,

12 × 6 + 6

Molar mass of Benzene is 78 g / mol

To find the number of moles,

7.8/78

The number of moles is 0.1 moles

Molar ratio between Benzene and carbon dioxide,

2 : 6 = 1 : 3

To find the number of moles on Co2,

0.1 × 3

The number of Co2 moles is 0.3 moles

At STP,

The volume is given by,

0.3 × 22400  

The volume of co2 liberated at STP on the complete combustion of 7.8g of benzene in presence of oxygen is 6720 cm^3