Calculate the number of particles in each of the following: (a) 78 g of nitrogen atom (b) 88 g of water molecules (c) 9.2 moles of oxygen atom
Answers
Answer:
Explanation:
You can solve this problem by using Dalton's Law of Partial Pressures, which states that the partial pressure of a component of a gaseous mixture depends on the mole ratio of said component and the total pressure of the gaseous mixture.
∣
∣
∣
∣
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
a
a
P
i
=
χ
i
×
P
total
a
a
∣
∣
−−−−−−−−−−−−−−−−−−
, where
P
i
- the partial pressure of component
i
χ
i
- its mole fraction in the mixture
P
total
- the total pressure of the mixture
Since you already know the total pressure of the mixture, focus on finding how many moles of each gas you get in the mixture.
To do that, use the molar masses of the two gases. You will have
54.5
g
⋅
1 mole O
2
32.0
g
=
1.703 moles O
2
68.9
g
⋅
1 mol CO
2
44.01
g
=
1.566 moles CO
2
The total number of moles present in the mixture will be
n
total
=
n
O
2
+
n
C
O
2
n
total
=
1.703 moles
+
1.566 moles
=
3.269 moles
Now, to get the mole fraction of a gas
i
that's part of a mixture, simply divide the number of moles of that gas by the total number of moles present in the mixture