## E23 (6th Edition)

Claudia Luong 4K
Posts: 59
Joined: Fri Sep 28, 2018 12:25 am

### E23 (6th Edition)

Hello! This may seem like a dumb question, but for all parts of this problem, we are finding the moles of the units specified in each part, so it is unnecessary to use Avogadro's number for any of these parts right?

The problem is: Calculate the amount (in moles) of (a) Cu2+ ions in 3.00 g of CuBr2; (b) SO3 molecules in 7.00 x 10^2 mg of SO3; (c) F- ions in 25.2 kg of UF6; (d) H2O in 2.00 g of Na2CO3x10H2O

Hovik Mike Mkryan 2I
Posts: 95
Joined: Fri Sep 28, 2018 12:25 am

### Re: E23 (6th Edition)

Hello,
Yes you do not need to use Avagadro's number to solve any of the parts in this question, just need to convert the molar masses to moles.

Katherine Grillo 1B
Posts: 69
Joined: Fri Sep 28, 2018 12:28 am

### Re: E23 (6th Edition)

Yes, you're right. You would only have to use Avagadro's number if it asked you to calculate the number of molecules or formula units as it did in question E21. In this case, the question is just asking for the number of moles so no need to use Avagadro's number.

Nathan Mariano 2G
Posts: 68
Joined: Fri Sep 28, 2018 12:29 am

### Re: E23 (6th Edition)

The use of Avogadro's number is only necessary when the problem is asking for the atoms of a molecule or formula units of a compound. In this case, the question is asking you to find the moles of each unit; therefore, it is unnecessary to multiply by Avogadro's number. Simply, convert the mass of the substance to moles by dividing by the atomic mass of the element or compound.

Hannah Pham 1D
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Re: E23 (6th Edition)

You don't need to use avogadro's number in this problem because it says calculate in moles.