Impure Samples and Percentage Purity Worksheet
1.  An impure sample of Na2SO4 has a mass of 1.56 grams. This sample is dissolved and allowed to react with BaCl2 solution. The precipitate has a mass of 2.15 grams. Calculate the percentage of Na2SO4 in the original sample.
2. An impure, 0.500 grams sample of NaCl was dissolved in 20.0 mL of water. The chloride ions were precipitated completely by addition of a AgNO3 solution. The dried AgCl precipitate has a mass of 1.15 
grams.

a) How many moles of AgCl formed?

b) How many moles of NaCl were in the sample?

c) How many grams of NaCl were in the sample?

d) What was the percentage of NaCl in the impure sample?
3. An impure sample of Na2SO4 has a mass of 1.65 grams and is dissolved in water. Addition of BaCl2 solution produced a precipitate of barium sulphate with mass 2.32 grams. What is the percentage of Na2SO4 in the impure sample?
4. A sample known to contain only NaCl and KCl has a mass of 1.08 grams. The sample is dissolved and treated with AgNO3 until precipitation is complete. The precipitate of AgCl has a mass of 2.32 grams. What is the percentage of NaCl in the mixture?
5. A mixture of Na2SO4 and K2SO4 having a total mass of 0.500 grams, was dissolved in water. Barium chloride was added as a precipitating agent. The dried BaSO4 resulting from the reaction has a mass of 0.715 grams. What is the percentage of each component in the original mixture?
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