Testing for Cation and Anions
• Determine the presence of a cation or anion by a chemical reaction • Determine the cation and anion in an unknown solution
All salt solutions have both positive (Cations) and negative (Anions) ions dissolved in it. In this experiment you will observe chemical reactions to determine the presence of specific anions and cations.
Compare your observations with the reactions of the known solutions and the unknown solution to determine the ions present in the unknown solution. You will use a flame test for the cations, Na+, K+, and Ca+2 Perform qualitative tests for Ca+2, NH4+, Fe+3.
Qualitative tests will be used to identify anions, Cl-, SO42-, PO43-, and CO32-. Expected results of the qualitative test and the reactions are included in your procedure. PROCEDURE:
Obtain from the stock room a solid unknown salt to be analyzed for the presence of both cation and anion.
HC1, HNO3 are strong acids and NaOH is a strong base so be careful when using them. Use the plastic pipettes on the center counter to dispense your unknown solution. Approx. 20 drops is equal to 1 mL,
All waste go in the waste jar labeled for your class.
Bunsen Burner Safety.
Make sure you are able to get a spark out of the striker consistently! Turn the gas needle valve counter clockwise completely.
Adjust the burner barrel so your are able to see through the air inlet Check the rubber tubing and place the rubber hose on the gas nozzle. Turn the gas jet 90 degrees.
Open the gas needle valve until you hear the gas and light.
If you are not successful in lighting the burner, turn the gas off and try again.
Al. Flame Test
• Label 3 test tubes, Na+, K+ and Ca+2. Bring the test tubes to the stockroom window to get your wood splint soaked in each of the solution. You will also be given an unused wood splint to use for your unknown. Get your solid unknown as well. • Soak the unused wood splint in water.
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