Page 232 - Chemistry eBook

Challenging Balancing Equations Example:
The coefficient applies to the entire NH3 molecule. Write these changes on the chart:
a. N: 1 x 2 = 2 (no subscript, so we do 1 × coefficient) b. H: 3 x 2 = 6 (subscript × coefficient)
Element
LEFT SIDE: Ca(OH)2 + (NH4)2 SO4
RIGHT SIDE: CaSO4+ NH3 + H2O
Ca
1
1
O
6 (O2+O4=O6)
6 (O4+O2=O6)
H
10 (H2 +H8)
10 (H3×2=6+H4=H10)
N
2
1×2=2
S
1
1
d. Now let’s check that the values on both sides are equal.
Element
LEFT SIDE: Ca(OH)2 + (NH4)2 SO4
RIGHT SIDE: CaSO4+ NH3 + H2O
Are both sides equal?
Ca
1
1

O
6 (2+4=6)
6 (4+2=6)

H
10 (2+8=10)
10 (6+4=10)

N
2
2

S
1
1

Answer: Ca(OH)2 + (NH4)2 SO4 CaSO4+ 2NH3 + 2H2O
231 © UNIT 6: MATH IN CHEMISTRY