Credit will be given for strict adherence to 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 is a mixture of two simple salts. Carry out the following exercises on C. Record your observations and identify any gases evolved. State the conclusion you draw from the result
(a)(i) Put all C in a boiling tube or beaker and add about 10cm\(^{3}\) of distilled water Stir the mixture thoroughly and tilter Keep both the residue and the filtrate
(ii) Test the filtrate with litmus paper.
(b) Divide the filtrate of two portions
(i) To the first portion of the filtrate. add about 2cm\(^3\) of dilute trioxonitrate (v) acid and then silver trioxonitrate (v) solution
(ii) To the second portion of the filtrate, add sodium hydroxide solution in drops until it is in excess.
(c) Put half of the residue in a test tube and heat strongly. Allow to cool
(d)(i) Put the remaining half of the residue in a test tube and add about 2cm\(^3\) of dilute hydrochloric acid.
(ii) To the resulting solution from (d(i)) above, add aqueous ammonia in drops until it is in excess.
Explanation
| Test | Observation |
Inference |
| (a)(i) C + water filtration | Partly soluble white milky suspension. White residue. colourless filtrate | Filtrate is neutral |
| (ii) Filtrate + litmus | No effect on litmus | Filtrate is neutral |
| (b)(i) Filtrate + dil HNO\(_3\) + AgNO\(_{3(aq)}\) |
No visible reaction White precipitate |
Cl\(^{-}\) present |
| (ii) Filtrate + NaOH\(_{(aq)}\) in drops and in excess |
White precipitate precipitate insoluble |
Ca\(^{2+}\) present |
| (c) Residue + heat | Residue turns yellow and white when cold | ZnO present |
| (d)(i) Residue + dil HCl | Effervescence/gas - evolved, odourless gas turns lime water milky |
Gas is CO\(_2\) CO\(_3^{2-}\) |
| (ii) Soln. from d(i) + NH\(_{3(aq)}\) in drops until in excess | white ppt. which is soluble gives a colourless soln. | Zn\(^{2+}\) confirmed |