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Answer (Continued)
3. Now let’s work on the S and O. If we add a coefficient of 3 to CuSO4, the S and O values will match. 2Al + 3CuSO4 Al2(SO4)3 + Cu
The coefficient of 3 applies to the Cu, S, and O4. Let’s multiply each atom by three.
4. Everything matches now, except Cu. If we add a coefficient of 3 to the right side of the equation, the values will match.
2Al + 3CuSO4 Al2(SO4)3 + 3Cu
Cu
1 x3 = 3
1
S
1x 3 = 3
1 x3 = 3
O
4 x 3 = 12
4 x 3 = 12
Element
LEFT SIDE: Al + CuSO4
RIGHT SIDE: Al2(SO4)3 + Cu
Al
2
2
Cu
3
1x 3 = 3
S
3
3
O
12
12
Answer: 2Al + 3CuSO4 Al2(SO4)3 + 3Cu Check to see if both sides are equal.
Element
LEFT SIDE: 2Al + 3CuSO4
RIGHT SIDE: Al2(SO4)3 + 3Cu
Are both sides equal?
Al
2
2

Cu
3
3 (1 x 3)

S
3
3 (1 x 3)

O
12 (4 x 3)
12 (4 x 3)

229 © UNIT 6: MATH IN CHEMISTRY