Page 251 - Chemistry eBook

Percent Composition of Hydrates Problem
Find the percent composition of water in the hydrate: MgSO4  10H2O. Answer:
1. Mass of water:
H: 1 x 2 x 10 = 20 (atomic mass × subscript × coefficient) O: 16 x 10 = 160 (atomic mass × subscript)
20 + 160 = 180
2. Mass of hydrate: Mg: 24
S: 32
O: 16 x 4 = 64 (atomic mass × subscript) 10H2O = 180 (calculated in step 1)
24 + 32 + 64 + 180 = 300
3. Mass of water Mass of hydrate
180 × 100
× 100
300 60% 0.6 x 100 =
UNIT 6: MATH IN CHEMISTRY © 250