Washing soda is Na₂CO₃ · 10H₂O: each formula unit of sodium carbonate holds 10 molecules of water.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Washing soda is : each formula unit of sodium carbonate holds molecules of water.
- Find its formula unit mass. Use and .
- What percentage of washing soda is water?
Need a reminder? The key ideaShow
Molecular mass (or formula unit mass, for an ionic compound) is the sum of the atomic masses of all the atoms in the formula, in u. The molar mass in g/mol has the same number.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) .
Step 2. (b) .
Answer: (a) . (b) : well over half of each crystal is water.
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