what is the number of ions in 2 moles of Ca(NO3)2?

what is the number of ions in 2 moles of Ca(NO3)2 ?
avogadro's constant = 6.02 x 10^23

i did
2 x 6.02 x 10^23 x 3
2 moles x the constant x 3 ions

my teacher said x 4 not 3 because Ca+2 and ((NO3)-)2 and we should multiply the charge by the number of the ions so (2x1)+(1x2)= 4

i asked on a school grp and they did what i did but my exam is tomorrow and i don't know who to follow, pls help is the grp or my teacher right?

Reply 1

AriatenNathan

the group and yourself are correct
Ca(NO3)2 -> Ca^(2+) + 2NO3^(-)
this is a 1:2 ratio, meaning there is 3 moles overall in one mole of Ca(NO3)2. since we have two moles, you do 3 x 2 = 6 moles total, and then multiply by avogadros constant.
the charge is useful for balancing the equation, but it doesnt impact how many ions are there.