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22 votes
22 votes
Show the conversions required to solve this problem and calculate the grams of Al2O3 .

User Wewals
by
2.6k points

1 Answer

23 votes
23 votes
This problem is an example of a gram-to-gram stoichiometry problem. You are given the mass of
Al
Al
in grams and you are asked to find the mass of
Al

2
O

3
Al
2


O
3

in grams. For questions such as this, the strategy is to convert from grams of
Al
Al
to moles of
Al
Al
, then to moles of
Al

2
O

3
Al
2


O
3

, and finally to grams of
Al

2
O

3
Al
2


O
3

.

grams Al⟶moles Al⟶moles
Al

2
O

3
⟶grams
Al

2
O

3
grams

Al

moles

Al

moles

Al
2


O
3



grams

Al
2


O
3


To convert grams of
Al
Al
to moles of
Al
Al
, you use the molar mass of
Al
Al
,
26.98 g/mol
26.98
g/mol
. The balanced chemical equation is used to relate the moles of
Al
Al
to the moles of
Al

2
O

3
Al
2


O
3

. There are 2 moles of
Al

2
O

3
Al
2


O
3

formed for every 4 moles of
Al
Al
that react. To convert moles of
Al

2
O

3
Al
2


O
3

to grams of
Al

2
O

3
Al
2


O
3

, you use the molar mass of
Al

2
O

3
Al
2


O
3

,
101.96 g/mol
101.96
g/mol
. This can be done one conversion at a time, or you can string the conversions together.

30.6 g Al×
1 mole Al
26.98 g Al

×
2 moles
Al

2
O

3
4 moles Al

×
101.96 g
Al

2
O

3
1 mole
Al

2
O

3

=57.8 g
Al

2
O

3


Hopefully the picture will show up this time.
Show the conversions required to solve this problem and calculate the grams of Al-example-1
User Alex Povar
by
3.0k points