Question

1) The number of molecules present in 80g methane is ​

Answer 1

Explanation:

To find the number of moles, all we have to do is use the following relationship:

Number of moles

=

Mass

Molar mass

And the molar mass of methane may be read straight off your Periodic Table:

Molar mass of methane,

C

H

4

=

(

12.011

+

4

×

1.00794

)

⋅

g

⋅

m

o

l

−

1

Mass

Molar mass

=

80

⋅

g

16.0

⋅

g

⋅

m

o

l

−

1

=

?

?

m

o

l

.

Note that this calculation is consistent dimensionally:

1

m

o

l

−

1

=

1

1

m

o

l

=

m

o

l