Empirical Formula of a Hydrate. In addition to this presentation, before coming to lab or attempting the prelab quiz you must also:
To name a hydrate, name the ionic compound, then indicate the amount of water of hydration by adding…
…a greek prefix to indicate the number of waters…
1 = mono; 2 = di; 3 = tri; 4 = tetra; 5 = penta; etc...
…and then the word hydrate
e.g., CuSO45H2O = copper (II) sulfate pentahydrate
Note: There is no way to predict the number of waters of hydration for a given ionic compound This must be obtained from experiment
Open flame heat source
Air mixes with gas here.The collar is adjustable to let more or less air in.
Gas goes in here
Use this valve to adjust gas flow
Don’t adjust from nozzle on bench
A hot blue flame can be obtained by raising the Bunsen Burner collar to allow more air in
A cooler, yellow flame can be obtained by lowering the Bunsen Burner collar to allow less air in
This type of flame is good if you need a low temperature, but is harder to control
This is generally an easier type of flame to control
Heating removes 0.438 g of H2O from a hydrate, leaving behind 0.562 g dry salt. If the salt has a molar mass of 161.26 g mol-1, what is the hydrate empirical formula?
0.562 g = 0.00349 mol salt
0.438 g = 0.0243 mol H2O
(0.0243 mol H2O) / (0.00349 mol salt) = 6.96
It would seem safe to say that there are 7 mol water for each mol salt