Mole Conversion

Recall: 1 mol = 6.022 E 23 units of substance

Conversion between particles and mole

1. Particles to mole

• multiplied particle/ formula units/ molecules by 1 mol/6.022 x 10^23
• Example:   How many moles of barium nitrate (BaNO3) contain 6.80 x 10^24 formula units?

• Well, to do this, divide 6.80 x 10^24 by Avagadro's number, 6.022 x 10^23, to get 11.29 moles. 

     2.  Mole to particle

• multiplied mole by 6.022 x 10^23/ 1 mol
• Example:  Determine the number of atoms that are in 0.58 mol of Se

• If you're thinking you multiply .58 moles by 6.022 x 10^23 atoms/mol, you're absolutely right. This yields the answer of 3.49 x 10^23 atoms of Se.

Conversion between moles and grams 

To do this type of questions, you have to know the molar mass of the substance.  Using the periodic table we can find the molar mass, or the mass of a mole of a substance.  The unit of the molar mass is grams/ mol

1. Moles to grams

•  multiply moles by _grams / 1mol
• Example:  how many grams are there in 2.04 moles of Carbon?

•  To do this question, first you have to find the molar mass of C and it is 12.0g/ mol. Then, you multiply 2.04 mole by 12.0g/ 1 mol and get the answer of 24.5g of C

     2. Grams to moles

• multiply grams by 1 mol/ _grams
• Example:  how many moles are in 3.45 g of Carbon?

• Well, the molar mass of Carbon is 12.0 g/ mol so you multiply 3.45 g by 12.0g/ mole and get the answer of 0.288 mol.

Harder mole conversion

the following question is more difficult and a mole map can help you understand it.

1. Particles to mass

• To do this type of question:
• Find the moles of the item you wish to convert
• Determine the molar mass of the item you wish to convert. (set up the conversion factor - this time moles are on the bottom)
• Set up the equation and solve  
• Example: what is the mass of 2.78 x 10^ 22 Fe atoms?

• To do this, we multiply 2.78 x 10^ 22 by 1 mol/6.022 x 10^23 and times the molar mass: 55.8 g/ 1 mole to the answer and get 2.58 g Fe

     2. Mass to Particles

• The rules for this type of questions are
• Find the mass of the item you wish to convert
• Determine the molar mass of the item you wish to convert.
• Set up the equation and solve.
• Example:  how manu atoms of Iron in 20.0 g of Iron?

• For this question, we time 20.0 g by the molar mass of the Iron : 1 mol/ 55.8 g, then we multiply the result 6.022 x 10^23/ 1 mol and get the result of the number of atoms, which is 2.16 x 10^ 23 atoms of Fe

Finally, this is a cool story about mole conversion. Watch it!