2C 13. An ionic compound (salt) is composed of one positive ion called cation an

Question

2C 13. An ionic compound (salt) is composed of one positive ion called cation and one negative ion called anion. A student was given an unknown sample of a salt to be analyzed. The ions that were analyzed in this unknown sample are: Na", K', Ca2, Fe*, Cu,Cr and CO. (5 pts) Complete the following table. Reagent added to Ion the sample Na CO AgNO a) Observations Result (lon present or not) A cloudy solution White precipitate Clear, colorless solution Clear, colorless solution No gas was released KSCN NH OH HCL (4 pts) After interpreting the results of the analysis given above, answer the following questions: b) The anion present is: The cation present is: The formula for the salt is: 14, (3 pts) Describe what happens when a few drops of iodine reagent are added to a solution that contains starch particles.

Explanation / Answer

a) A cloudy solution on addition of Na2CO3 confirms the presence of Ca2+

A white precipitate on addition of AgNO3 confirms the presence of Cl-

The other reagents have no effect, therefore we can safely conclude that the identification is correct.

b) Anion Present: Cl-

Cation Present: Ca2+

Formula of Salt is: CaCl2

14. When iodine is added to a solution containing starch particles, it turns very dark blue-black color. In absence of starch, the solution retains its brown color.

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