Credit will be given for strict adherence to the instructions, for observations precisely recorded and accurate inferences. All tests, observations and inferences must be clearly entered in your als book, in ink, at the time they are made.
C is a mixture of an inorganic and organic compounds. Carry out the following exercises on C: Record your.observations and identity any gases evolved. State the conclusion you draw from the result of each test.
(a) Put all of C into a beaker and add 10 cm\(^3\) of distilled water: Stir the mixture thoroughly and filter. Keep both the filtrate and residue.
(b)(i) Test the filtrate with litmus paper.
(ii) To about 2 cm\(^3\) of the filtrate, add BaCI\(_{2(aq)}\) followed by dilute HCI:
(iii) To another 2 cm\(^3\) portion of the filtrate add NaOH and heat.
(c) Transfer the residue into a boiling tube and add few drops of iodine solution
Explanation
| Test | Observation | Inference |
| C + water and filter | Partially soluble in water. Colourless filtrate and white residue | C is a mixture of soluble and insoluble salt |
| Filtrate + litmus paper | Turned blue litmus paper red |
Filtrate is acidic |
|
Filtrate + BaCl\(_2\) ppt + dill. HCl |
White precipitate precipitate insoluble |
CO\(_3^{2-}\), SO\(_4^{2-}\) or SO\(^{2-}_3\) present SO\(_4^{2-}\) present |
| Filtrate + NaOH\(_{(aq)}\) + heat | Gas evolved with irritating or choking or pungent smell fumed with conc. HCl or turned red litmus paper blue | Gas is NH\(_3\) from NH\(_4^+\) |
| Residue + few drops of I\(_2\) solution | Blue-black or dark blue colouration | starch present |