2. You are provided with solid F. Carry out the following tests and write your observations and inferences in the spaces provided.
(a) Place half of solid F into a clean dry test tube. Heat it gently then strongly and test any gas produced using both blue litmus papers.
| Observations | Inferences |
|---|---|
| Colourless liquid forms at the cooler parts of the test tube. | Hydrates salt or Contains water of crystallization |
| Blue litmus paper changes to red | Acidic gas produced |
(1 mark) per row
b) Place the rest of solid F in boiling tube. Add about 15 cm³ of distilled water. Shake well. Divide the resultant solution into about 2 cm³ portions.
i) To about 2cm³ of solution F, add 2M sodium hydroxide drop wise until in excess
| Observations | Inferences |
|---|---|
| White precipitate soluble in excess NaOH | Zn2+, Al3+, Pb2+ present |
(1 mark) per row
(ii) To about 2cm³ of solution F, add 2M ammonia solution drop wise until in excess
| Observations | Inferences |
|---|---|
| White precipitate insoluble in excess ammonia solution | Al3+, Pb2+ present |
(1 mark) per row
(iii) To 2cm³ of solution F, add about 5 drops of sodium chloride
| Observations | Inferences |
|---|---|
| No white precipitate | Al3+ present |
(1 mark) per row
(iv) To 2cm³ of solution F, add 2-3 drops of aqueous barium nitrate followed by 3 cm³ of nitric (v) acid
| Observations | Inferences |
|---|---|
| White precipitate insoluble in the acid or White precipitate which persist on addition of nitric acid. |
SO42- present |
(1 mark) per row
3.(a) Dissolve solid G in about 10cm³ of distilled water in a boiling tube. Use the solution for tests a (i), (ii) and (iii).
(i) To 2cm³ of the solution G, add all of solid sodium hydrogen carbonate provided.
| Observations | Inferences |
|---|---|
| No effervescence/No bubbles/No fizzing/No bubbling | R-COOH absent |
(ii) Place 2cm³ of the solution G in a test tube and add 2 drops of acidified potassium dichromate (VI). Warm the mixture.
| Observations | Inferences |
|---|---|
| Orange acidified potassium dichromate changes to green | R-OH present |
(1 mark) per row
(iii) To 2cm³ of the solution G, add 2-3 drops of bromine water.
| Observations | Inferences |
|---|---|
| Bromine water is decolorized or Yellow bromine water changes to colorless. |
-C=C- or -C≡C- present (1 mark) |
(1 mark) per row