Question

Aluminum sulfate, Al2(SO4)3, is a compound used in sewage treatment plants.a) Select a pair of conversion factors that relate moles of Al to moles of S.b) Construct a pair of conversion factors that relate moles of S to moles of Al2(SO4)3.c) How many moles of Al are in a sample of this compound if the sample also contains 1.97 mol S?d) How many moles of S are in 1.71 mol Al2(SO4)3?

Answer 1

1) Convert moles of Al to moles of S (a).

The ratio of Al to S in the compound is 2 Al: 3 S.

`\frac{2molAl_{}}{3molS_{}}`
`\frac{3molS_{}}{2molAl_{}}`

2) Convert moles of Al2(SO4)3 to S (b).

The ratio of S to the Al2(SO4)3 is 3 S: 1 Al2(SO4)3.

`\frac{3molS_{}}{1molAl_2(SO_4)_3}_{}`
`\frac{1molAl_2(SO_4)_3}{3molS_{}}`

3) Moles of Al in the sample if the sample contains 1.97 mol S (c).

Convert moles of S to moles of Al.

`molAl_2(SO_4)_3=1.97molS\cdot\frac{2molAl_{}}{3molS_{}}_{}=1.31molAl_{}`

There is 1.31 mol Al in the sample.

4) Moles of S in 1.71 mol Al2(SO4)3

Convert moles of Al2(SO4)3 to moles of S

`molS_{}=1.71molAl_2(SO_4)_3\cdot\frac{3molS_{}}{1molAl_2(SO_4)_3}=5.13molS_{}`

There is 5.13 mol S in the sample