Chemistry...the mole concept?

Question

Calculate the no. of moles in 4.6g of Sodium. (Formula mass Na=23) How would this be done? Can u show working to help me understand it better?

Answer 1

have you previously been introduced to the mole triangle?

   m

n     M

where:

m=mass

n=moles

M=molar mass

To use the molar triangle, cover which one you are looking for and calculate. In this case, you are finding the number of moles. So, cover the "n" and you will get n= m/M.  You know that m(mass) is 4.6g and you also know that M(molar mass) is 23. So, now divide them. n= 4.6/23

you get 0.2 moles.

Hope this helps!

Answer 2

4.6gNa(1mol/23gNa)

when you do this the unit g cancels out and you are left with moles.

you would use this equation because the formula mass means that for every one mole of Na there are 23 grams so you want to calculate how many moles will be in 4.6 g.  you will divide 4.6 by 23 and be left with 0.2

the concept can be a bit challenging but I hope I helped.