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

1 Answer
Sep 6, 2017

Answer:

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?