## Avagrado's Number [ENDORSED]

Natalie_Martinez_1I
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Joined: Mon Feb 26, 2018 3:00 am

Can 6.022x10^23 be used in calculations to represent both the number of molecules in a mole and atoms in a mole of a substance? Like can you use 6.022x10^23 atoms to represent a mole or only 6.022x10^23 molecules to represent a mole?

sylvie_1D
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Joined: Fri Apr 06, 2018 11:04 am

### Re: Avagrado's Number

I had this question as well! In the solutions manual they use atoms/molecules interchangeable with Avogadro Number so I assume yes, however that is an assumption.

Posts: 31
Joined: Fri Apr 06, 2018 11:03 am

### Re: Avagrado's Number

It's usually for the number of molecules or atoms, depending on the question, but if you have something that asks for the number of molecules AND then the number of atoms, you can do the following. You would first use Avogadro's constant for the number of molecules, then you multiply that by the literal number of atoms. So if the molecule is H2O, where there are three atoms, 2 H and 1 O, you would multiply the number of molecules you got with 3, which is the number of atoms.

Sonia Aronson 1B
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### Re: Avagrado's Number  [ENDORSED]

6.022x10^23 represents the number of objects per mole. It can be used to calculate the number of atoms or molecules in a given number of moles. So atoms and molecules are used interchangeably for Avogadro's Number.

Paywand Baghal
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Joined: Fri Apr 06, 2018 11:01 am

### Re: Avagrado's Number

joannehaddad wrote:It's usually for the number of molecules or atoms, depending on the question, but if you have something that asks for the number of molecules AND then the number of atoms, you can do the following. You would first use Avogadro's constant for the number of molecules, then you multiply that by the literal number of atoms. So if the molecule is H2O, where there are three atoms, 2 H and 1 O, you would multiply the number of molecules you got with 3, which is the number of atoms.

So would you have to multiply Avogadro's number by 3 if you are trying to find the mass of H20 in your calculations?

Posts: 31
Joined: Fri Apr 06, 2018 11:03 am

### Re: Avagrado's Number

Paywand Baghal wrote:
joannehaddad wrote:It's usually for the number of molecules or atoms, depending on the question, but if you have something that asks for the number of molecules AND then the number of atoms, you can do the following. You would first use Avogadro's constant for the number of molecules, then you multiply that by the literal number of atoms. So if the molecule is H2O, where there are three atoms, 2 H and 1 O, you would multiply the number of molecules you got with 3, which is the number of atoms.

So would you have to multiply Avogadro's number by 3 if you are trying to find the mass of H20 in your calculations?

You would multiply Avogadro's number by 3 if you are trying to find the number of atoms of H2O from a given mass, not the mass of H2O. To clarify, here's an example below that should help to explain what I was trying to say more clearly.

How many atoms of oxygen are in 5g of HNO3?

Step 1: Find the number of moles of HNO3 (using its molar mass)
Step 2: Use Avogadro's constant to find the number of molecules of HNO3
Step 3: Multiply the result from step 2 by the number 3 (because in this compound, you have 3 atoms of oxygen)

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### Re: Avagrado's Number

Avagadros number can be used to represent the number of molecules, atoms, and formula units. It is just the number we use to find out how much of one of those three is in what we are looking at.

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