Question

What molar quantity is associated with `19.32*g` mass of magnesium metal?

Answer 1

Well, we know that `1*mol` of magnesium has a mass of `24.31*g`...so..............

Explanation:

.......so we take the quotient....

`"Moles of Mg"=(19.32*g)/(24.31*g*mol^-1)~=0.80*mol`....

....which of course is dimensionally consistent...........in that we get `cancelg/(cancelg*mol^-1)=1/(1/(mol))=mol` as required.........i.e. `1/(1/x)=x`

What is the physical significance of this quantity? It tells us that there are `0.8*molxxN_A=0.80*molxx6.022xx10^23*mol^-1` individual particles of magnesium in the sample......

By this reasoning, there are `N_A` individual particles of magnesium in the sample whose mass is `24.31*g`. How did I know these numbers?