Credit will be given for strict adherence to the instructions, for observations precisely recorded and for accurate inferences. All tests, observations, and inferences must be clearly entered in your answer book, in ink, at the time they are made.
C and D are inorganic salts. E is a solution of an organic compound. Carry out the following exercises on C, D and E. Record your observations and identify any gas(es) evolved. State the conclusion you draw from the result of each test.
(a) To all of C, add about 2 cm\(^3\) of distilled water in a boiling tube. Shake to dissolve and test the solution with litmus paper.
(b)i) Test E with litmus paper.
(ii) Add all of E to the solution obtained in (a).
(c)(i) Add about 5 cm\(^3\) of distilled water to D in a test tube and shake thoroughly. Divide the resulting solution into two portions.
(ii) To the first portion, add few drops of BaCl\(_{2(aq)}\) followed by excess dil. HCl.
(iii) To the second portion, add HNO\(_{3(aq)}\) in drops and then in excess.
Explanation
| TEST | Observation | Inference |
| (a) C\(_{(s)}\) + H\(_2\)O + litmus paper | Red litmus paper turned blue | Alkaline/Basic solution |
| (b)(i) E\(_{(aq)}\) + litmus paper | Blue Litmus paper turned red | Acidic solution |
| (ii) E\(_{(aq)}\) + C\(_{(aq)}\) |
Effervescence occurred Colourless and odourless gas which turned water milky was evolved |
CO\(_2\) gas from HCO\(_3^-\)/CO\(_3^2\) |
| (c)(i) D\(_{(s)}\) + H\(_2\)O | D dissolved to give a colourless solution | D is a soluble salt |
|
(ii) D\(_{(aq)}\) + BaCl\(_{2(aq)}\) + dil HCl(\(_{excess}\)) |
White precipitate Precipitate insoluble |
SO\(^{2-}\) or SO\(_3^{2-}\) or CO\(_3^2\) or SO\(_4^{2-}\) SO\(_4^{2-}\) present |
|
(iii) D\(_{(aq)}\) + NH\(_{3(aq)}\) in drops then in excess |
White gelatinous precipitate Precipitate dissolved |
Zn\(^{2+-}\) or AL\(^{3+}\) Zn\(^{2+-}\) confirmed |