A 1.85 mole sample of the ionic compound Al2(SO4)3 contains how many moles of the following? A) Al atoms B) S atoms C) Al3^+

1 Answer
Jul 18, 2017

Answer:

(a) #3.70# #"mol Al"#

(b) #5.55# #"mol S"#

(c) #3.70# #"mol Al"^(3+)#

Explanation:

We're asked to find the number of moles of some species in #1.85# #"mol Al"_2"(SO"_4")"_3#.

(a)

The moles of #"Al"# atoms:

There are #2# atoms of #"Al"# per unit of #"Al"_2"(SO"_4")"_3#, so there are two moles of #"Al"# per mole of #"Al"_2"(SO"_4")"_3#:

#1.85cancel("mol Al"_2"(SO"_4")"_3)((2color(white)(l)"mol Al")/(1cancel("mol Al"_2"(SO"_4")"_3))) = 3.70# #"mol Al"#

(b)

The moles of #"S"# atoms:

There are #3# atoms of #"S"# per units of #"Al"_2"(SO"_4")"_3#, so there are #3# moles of #"S"# per mole** of #"Al"_2"(SO"_4")"_3#:

#1.85cancel("mol Al"_2"(SO"_4")"_3)((3color(white)(l)"mol S")/(1cancel("mol Al"_2"(SO"_4")"_3))) = 5.55# #"mol S"#

(c)

The moles of #"Al"^(3+)# ions:

The number of ions of #"Al"^(3+)# will be the same as the number of atoms of #"Al"#, so the answer will be the same as that for (a) (assuming I understand the question correctly).