Question

pls help me...
chlorophyll contains 2 % by mass of Mg . The number of Mg atoms in 2 g chlorophyll is
a. 10 ^ 21
b. 10 ^ 23

how to do this??
i got 2= mass of Mg /mass of chlorophyll * 100
is that right? i dont know 2 continue...help.

Answer 1

You need to calculated 2% of 2g - that will give you the mass of magnesium.
Then calculate the moles of magnesium (mass/atomic mass).
The number of atoms is moles of magnesium x the number of particles in 1 mole