(ii) Number of molecules of CH4 in 80.0 g of it
Answers
Answer:
There are
1.8021
⋅
10
24
molecules of
C
H
4
in 48 grams of
C
H
4
.
Explanation:
To answer this question, you must understand how to convert grams of a molecule into the number of molecules. To do this, you have to utilize the concepts of moles and molar mass.
A mole is just a unit of measurement. Avogadro's number is equal to
6.022
⋅
10
23
molecules/mole. This number is the number of molecules of a specific compound in which when you multiply the compound by it, it converts atomic mass into grams.
For example, one mole of hydrogen gas (
H
2
) or
6.022
⋅
10
23
molecules of
H
2
weighs 2.016 grams because one molecule of
H
2
has an atomic weight of 2.016.
So the overall solution for this problem is to use molar mass of
C
H
4
(methane) to convert grams of methane into moles of methane. Then, use Avogadro's number to convert moles of methane into molecules of methane.
One mole of methane equals 16.04 grams because a molecule of methane has an atomic weight of 16.04. The conversion factor will be 16.04 grams/mole.
48
g
C
H
4
⋅
1
m
o
l
C
H
4
16.04
g
C
H
4
⋅
6.022
⋅
10
23
m
c
l
s
C
H
4
1
m
o
l
C
H
4
When you multiple and divide everything out, you get
1.8021
⋅
10
24
molecules of
C
H
4
Notice this is a modified T-chart so the grams
C
H
4
cancels out when you do the first conversion, and the moles
C
H
4
cancels out when you do the second conversion. This leaves you with the unit molecules of
C
H
4
which corresponds to what the question asks.
Answer:
ch4=80.0g
molecules =12+4=16
=80/16
=5
ch4 molecules =5