ApchemWiki | RecentChanges | Preferences
Showing revision 2
Percent By Mass of a Hydrate
What does that mean?
Some compounds have water included in their compound, and they are called hydrates.
The formula has the coumpound, like Zinc Nitrate and then the moles of water that are in the compound. (ex. Zn(NO3)2*6H2O)
However, on some problems the information given does not unclude the number of moles of water in the hydrate. The problem will give the percent by mass of the compound in the entire hydrate.
Problem: A student weighs 200g of the hydrate ZnSO4?*XH2O. The compound is 75% ZnSO4? by mass. How many moles of water are in the hydrate?
Steps for the Math:
- First of all, make sure you understand what the problem wants. The X befpre the water in the compound is the variable the problem asks for.