Question

Academic Year 2019-2020 Chemical Reactions and Writing Chemical Equations Post Lab Questions (10 Points). Answer the following question on this sheet or in your laboratory notebook. In lab you are given 4 bottles, each containing about 5 grams of a white substance. Near the bottles are four labels indicating each bottle contains a high purity substance. Assume these labels belong to the bottles and that each bottle contains a single substance. The four bottles contain glucose (C6H1206), sodium chloride (NaCl), aluminum oxide (Al2O3), and zinc sulfate (ZnSO4). Using your knowledge of solubility rules and electrolytic behavior, describe tests that you could conduct to determine which label belongs to which bottle. For these tests you may only use DI water, an aqueous solution of barium nitrate, and a conductivity tester to identify the substance in each of the bottles. Give the results you would expect for each test.

Answer 1

given compounds are

glucose
NaCl
Al2O3
ZnSo4
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firstly we can conduct solubility test
take little bit of each sample in 4 test tube
Add water to it and shake well
All salts except Al2O3 will be soluble in water .
So insoluble salt can be labelled as Al2O3
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above 3 salt solution in water can be tested for conductivity.
NaCl,ZnSO4 salt solution will conduct electricity, because they are ionic compounds

where as glucose water will not conduct electricity ,since it is a molecular compound
Thus the sample which will not conduct electricity can be labelled as glucose
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To the unknown salt solution add Ba(NO3)2 ,if precipitate formation happens
the salt is ZnSO4
NaCl will not form precipitate with Ba(NO3)2

ZnSO4 + Ba(NO3)2 ---> Zn(NO3)2 (aq) + BaSO4 (s) precipitate formed

NaCl (aq) + Ba(NO3)2 ----> No precipitate formation
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Thank you