Question

How many molecules would 3.45 moles of methane (CH4)

Answer 1

How to answer the question? ⬇️
(Btw this is an example on how to solve it so just letting you know)

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.

This is something else and is not connected with the one above this comment.

The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles CH4, or 16.04246 grams.

Or

Therefore 3.4 grams of ammonia is equal to 0.1996359579590159 moles of ammonia. Multiplying this by 6.022 * 1023 we get 120220773882919374980000 molecules (or 1.2022 * 1023 molecules). ...