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

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SUMMARY

The discussion centers on calculating the number of O2 molecules from a given number of moles, specifically 1.82 moles. The correct calculation involves using Avogadro's number (6.022 x 10^23) directly with the number of moles, leading to the conclusion that the number of O2 molecules is 1.82 moles multiplied by Avogadro's number, resulting in approximately 1.10 x 10^24 molecules of O2. The initial confusion arose from incorrectly multiplying the moles by 2, which pertains to the number of oxygen atoms rather than O2 molecules.

PREREQUISITES
  • Understanding of moles and Avogadro's number (6.022 x 10^23)
  • Basic knowledge of molecular composition (e.g., O2 consists of 2 oxygen atoms)
  • Familiarity with stoichiometry in chemical equations
  • Ability to perform basic arithmetic operations with scientific notation
NEXT STEPS
  • Study the concept of Avogadro's number in detail
  • Learn about stoichiometric calculations in chemical reactions
  • Explore the differences between moles, molecules, and atomic mass
  • Practice problems involving conversions between moles and molecules
USEFUL FOR

Chemistry students, educators, and anyone involved in chemical calculations or stoichiometry will benefit from this discussion.

axer
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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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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.
 
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?
 
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?
 
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
 
axer said:
Oh.. so the number of molecules is just no. of moles times molar mass?
no need to multiply by 2?
Right.
 
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.
 
mfb said:
Right.

Beware: part of the OP answer was plainly wrong.
 

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