Question

Consider a mixture of the two solids BaCl2 * 2H2O (FW=244.26 g/mol) and KCl (FW=74.551 g/mol). When the mixture is heated to 160 C for 1 hour, the water of crystallization is driven off:
BaCl2 * 2 H2O (s)  BaCl2(s) + 2 H2O(g)
A sample originally weighing 1.7839 g is found to weigh 1.5623 g after heating. Calculate the weight percent of Ba, K, and C1 in the original sample

Answer 1

1.7839g = mass BaCl2.2H2O + KCl
-1.5623g = mass after heating
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0.2216g = mass H2O driven off.
mass BaCl2.2H2O = 0.2216 x (molar mass BaCl2.2H2O/2*molar mass H2O) = ?
Then 1.7839-mass BaCl2.2H2O = mass KCl.
I will leave it for you to finish the problem. Post your work if you get stuck.