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 centered in your answer book, at the time they are made.
C is a mixture of two salts. Carry outline following exercises on C. Record your observations and identify any gas(es) evolved. State the conclusion you draw from the result of each test.
(a) Put C into a beaker and add about 10 cm\(^3\) of distilled water, stir the mixture, and filter. Test the filtrate with litmus paper. Keep the residue and the filtrate.
(b)(i) To about 2 cm\(^3\) of the filtrate, add few drops of aqueous HNO\(_3\) followed by AgNO\(_{3(aq)}\)
(ii) Add excess NH\(_3\) solution to the resulting mixture.
(c) To about half of the residue from (a) above, add about 5cm\(^3\) of dilute HNO\(_3\) in drops. Divide the resulting solution into two equal portions.
(d)(i) To the first portion add ammonia solution in drops and then in excess.
(ii) To the second portion add dilute hydrochloric acid.
Explanation
| Test | Observation | Inference |
|
(a) C + water Mixture filtered Filtrate 1 litmus |
Partly dissolves Colourless filtrate white residue No effect on litmus |
C contains solution and insoluble salts Filtrate is neutral |
|
(b)(i) Filtrate + dil. H\(_2\)SO\(_4\) + AgNO\(_{3(aq)}\) (ii) Mixture in (b)(i) + excess NH\(_3\) soln |
No reaction white ppt ppt dissolves |
Cl\(^-\) present
Cl\(^-\) confirmed |
| (c) Residue + dil. HNO\(_3\) | Effervescence occurs, gas turns lime water milky |
CO\(_2\) CO\(_3^{2-}\) present |
|
(d)(i) First portion + dil. NH\(_3\) in drops then in excess (ii) Second portion + dil. HCl |
White ppt ppt insoluble White chalky ppt |
Pb\(^{2+}\) may be present Pb\(^{2+}\) present Pb\(^{2+}\) confirmed |