DATA: 2 g Unknown number. 2/, O 1 Mass of crucible lid 2 Mass of crucible and hy
ID: 531408 • Letter: D
Question
Explanation / Answer
1)Mass of crucible and hydrate+lid=21.9607g
Mass of crucible +lid=21.0278g
mass of hydrate=0.9329g
mass of anhydrous compound(residue)`=Mass of crucible and residue+lid(2nd heating)-mass of crucible and lid=21.5580g-21.0278g=0.5302g
Mass of crucible and hydrate+lid=21.9607g
Mass of crucible and residue+lid(2nd heating)=21.5580g
mass of water lost=21.9607g-21.85580g=0.4027g
2)% water (by mass)=(mass of water lost/mass of hydrate)*100=0.4027/0.9329*100=43.1665%
3)mass of sample=0.815g
mass of water=43.1665% of 0.815g=43.1665/100 *0.815=0.3518g
4)mass of water#1=0.4027g
moles of water=0.4027g/molar mass of water=0.4027g/18g/mol=0.0223 moles
moles of MgSO4=mass of residue/molar mass of MgSO4=0.5302g/120.366g/mol=0.00440mol
moles of water=0.0223 moles/0.00440mol=5.0
formula=MgSO4.5H2O
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