Question

how many grams of oxygen gas will be
required to completely react with 3 moles of C3H8.
​

Answer 1

C

3

H

8

+5O

2

→3CO

2

+4H

2

O

The molar masses of C

3

H

8

,O

2

,CO

2

are 44g/mol, 32g/mol and 44g/mol respectively.

The number of moles is the ratio of mass to molar mass.

The number of moles of C

3

H

8

=

44g/mol

88g

=2mol

Number of moles of O

2

=

32g/mol

160g

=5mol

2 moles of propane will react with 2×5=10 moles of oxygen, however, only 5 moles of oxygen are present.

Hence, oxygen is the limiting reagent and propane is the excess reagent.

5 moles of oxygen will give 3 moles of CO

2

.

Mass of CO

2

=3 mol×44 g/mol=132 g

HOPE THIS HELPS U