What is the molar mass of #Al_2(SO_4)_3#?

1 Answer
Tajadoru · Ernest Z.
May 31, 2016

#"342.13 g/mol"#

Explanation:

The molar mass of #Al_2(SO_4)_3# can be determined by adding the individual masses of each atom. These masses can easily be obtained from a periodic table.

Start with #Al_2#

The atomic mass is #"26.982 g/mol"#.

But there are two #Al# so multiple by 2 and get #"53.964 g/mol"#
Leave this number here for now. We will revisit this later.

Now we have to calculate for #(SO_4)_3#

Same thing! Add the atomic masses from the periodic table. Remember there are 4 oxygens per sulfur! Add all those and you should get an answer close to #"96.062 g/mol"#.

Wait! There are three sulphates so multiply by 3. The answer should be #"288.186 g/mol"#

The question asks for the molar mass of the two ions I just calculated for. Simply add the two results for your answer :-)

#"(53.946+288.186) g/mol" = "342.132 g/mol"#

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