Qualitative Analysis on Compound X in order to identify cations and anions present
Aim / Objective:
To perform qualitative analysis tests on compound X in order to identify cations and anions present.
Qualitative analysis is a technique that is used to separate and detect cations and anions in a sample. Anions are atoms or groups of atoms that have gained an electron or electrons. The atoms that form ions most easily are the Group 17 or VII atoms, also called halides: Fluorine (F), Chlorine (Cl), Bromine (Br) and Iodine (I). These form anions with a -1 charge. Oxygen (O), Sulphur (S), Nitrogen (N) and Phosphorus (P) also form anions. Most anions are composed from multiple atoms, and are called polyatomic ions.
Cations are atoms that have lost an electron to become positively charged. For example: Sodium (Na) has one valence electron, one electron in its outer energy level, so it tends to lose one electron, and to become an ion with a +1 charge
Bunsen burner, red litmus paper, blue litmus paper, distilled water, test tube rack, test tubes, glass stirring rod, metal test tube holder, dilute nitric acid (HNO3), sodium hydroxide (NaOH), potassium iodide (KI), barium chloride (BaCl2), ammonia solution, lead nitrate (Pb(NO3)2), silver nitrate (AgNO3), dilute hydrochloric acid (HCl), splint, dropper, compound X.
Method / Procedure:
- Heat solid compound X in a dry test tube.
- Test the gas evolved with red and blue litmus paper and a glowing splint.
- Record the observations.
- To a solution of compound X in a test tube add distilled water and dilute HNO3, then add AgNO3 and note observations.
- In a test tube mix solution X with distilled water, then add dilute HNO3 and BaCl2 to the mixture. Record the observations.
- In a test tube mix solution X with distilled water and heat the test tube moderately. Add dilute HNO3 and Pb(NO3) to the heated mixture. Record the observations.
- Mix a small portion of solution X with distilled water in a test tube. Use a dropper to add NaOH in excess to the mixture and heat test tube moderately. Record your observations.
- Mix a small portion of solution X with distilled water in a test tube. Add excess ammonia to the mixture and note the results.
- Half fill a test tube with solution X and add KI(aq). Record the observations.
- Half fill a test tube with solution X, add NaOH(aq) and heat the test tube moderately. Dip the glass stirring rod with the mixture in a beaker of HCl. Test the gas evolved with litmus paper. Record the observations.
- Tabulate results
- The cations present In compound X were Al3+ and NH4+
- The anions present were SO42- and Cl–