Calculate the number of molecules of O2 when given the number of moles

In summary, after balancing an equation, there are 1.82 moles of O2. To calculate the number of molecules of O2, you simply multiply the number of moles by Avogadro's number, 6.02×10^23, resulting in 2.19×10^24 molecules of O2. It is important to remember that the number of molecules is not affected by the number of atoms in each molecule, as one mole of any substance contains 6.02×10^23 molecules.
  • #1
axer
35
4

Homework Statement


After balancing an equation, there are 1.82 moles of O2.

Calculate the number of molecules of O2. given moles.

Homework Equations

The Attempt at a Solution


in every O2 molecule, there are 2 moles of O.
so if the number of moles of O2 molecule is 1.82. then 1.82*2= 3.65 moles.

number of molecules= 3.65*6.022*10^23= 2.19*10^24.
Correct?
 
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  • #2
axer said:
in every O2 molecule, there are 2 moles of O.
In every single molecule?
axer said:
number of molecules= 3.65*6.022*10^23= 2.19*10^24.
Correct?
That is the number of oxygen atoms. The question asked about the number of O2 molecules.
 
  • #3
mfb said:
In every single molecule?That is the number of oxygen atoms. The question asked about the number of O2 molecules.
Oh.. so the number of molecules is just no. of moles times molar mass?
no need to multiply by 2?
 
  • #4
axer said:
Oh.. so the number of molecules is just no. of moles times molar mass?

Number of moles times molar mass is a sample mass.

Think about a mole as of an overgrown dozen, with 6.02×1023 objects instead of 12. You have two dozens of molecules - how many molecules? You have two moles of molecules - how many molecules?
 
  • #5
Borek said:
Number of moles times molar mass is a sample mass.

Think about a mole as of an overgrown dozen, with 6.02×1023 objects instead of 12. You have two dozens of molecules - how many molecules? You have two moles of molecules - how many molecules?
2*6.02×1023

the question included no of moles
 
  • #6
axer said:
Oh.. so the number of molecules is just no. of moles times molar mass?
no need to multiply by 2?
Right.
 
  • #7
Maybe you have go the question confused with the other possible similar kind of questions.
Forget everything you know about oxygen - it's irrelevant here.
Calculate the number of molecules of anything in 1.82 moles of that thing.
Is the same for anything.
 
  • #8
mfb said:
Right.

Beware: part of the OP answer was plainly wrong.
 

1. How do you calculate the number of molecules of O2 when given the number of moles?

The number of molecules of O2 can be calculated using Avogadro's number, which is equal to 6.022 x 10^23 molecules/mol. Simply multiply the given number of moles by Avogadro's number to get the number of molecules of O2.

2. What is Avogadro's number?

Avogadro's number is a constant that represents the number of particles (atoms, molecules, or ions) in one mole of a substance. It is equal to 6.022 x 10^23 molecules/mol.

3. Can the number of molecules of O2 be calculated using any other method?

Yes, the number of molecules of O2 can also be calculated using the ideal gas law, which relates the number of moles of a gas to its pressure, volume, and temperature. However, this method requires additional information about the gas's properties.

4. What is the relationship between moles and molecules?

Moles and molecules are related by Avogadro's number. One mole of a substance contains the same number of particles as Avogadro's number, regardless of the substance's molecular weight. Therefore, the number of molecules can be calculated by multiplying the number of moles by Avogadro's number.

5. Why is it important to calculate the number of molecules of O2?

Calculating the number of molecules of O2 is important in various scientific fields, such as chemistry and biology. It allows us to accurately measure and understand the amount of a substance present in a given sample, which is crucial in chemical reactions and biological processes.

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