## Conversion of grams to moles

duverge_maciel
Posts: 21
Joined: Fri Sep 28, 2018 12:16 am

### Conversion of grams to moles

If an element given contains a subscript of 2,3, etc, does the molar mass of the element need to be multiplied by that subscript in order to find the moles of the element?

Yvonne Du
Posts: 64
Joined: Fri Sep 28, 2018 12:23 am

### Re: Conversion of grams to moles

Yes. For example, if the question asks you to convert 2.0g of CO2 to moles. What you do is first add up the molar mass for CO2 which is 12.011(C)+15.999*2(O)=44.009grams. Then you use 2/44.009 to get the moles. You always consider the subscripts.

LedaKnowles2E
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

### Re: Conversion of grams to moles

Yes, if I understand what you're asking.
For example, the molar mass of plain oxygen, O, is 16 g/mol.
But the molar mass of oxygen gas, O2, is 2x16= 32 g/mol.
Hope that helps.

Ethan Nishikawa 4D
Posts: 36
Joined: Fri Sep 28, 2018 12:16 am

### Re: Conversion of grams to moles

Yes, the molar mass of the element needs to be multiplied by the subscript in order to find the chemical formula.

Furthermore, the subscript indicates the number of moles.

Sarah_Kang_2K
Posts: 72
Joined: Fri Sep 28, 2018 12:23 am

### Re: Conversion of grams to moles

Yes, you need to take into account subscripts when finding the molar mass of a compound.
For example, in order to find the molar mass of CO2, you would add the molar mass of carbon plus twice the molar mass of oxygen. This gives you the molar mass of CO2. You can then use the molar mass of CO2 and the amount in grams of CO2 to determine the moles of CO2 present.