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. Sate the conclusion you draw from the result of each test.
(a) Put all of C into a beaker of boiling tube and add about 10cm\(^3\) of distilled water. Stir well and filter. Keep the residue and keep the residue and the filtrate. Test the filtrate with litmus
(b) Add about 1 cm\(^3\) of dilute hydrochloric acid to the residue in a test tube and warm gently Divide the reaction mixture into two portions.
(c)(i) To the first portion from (b) add saturated sodium trioxocarbonate (V) solution in excess.
(d) To about 2cm\(^3\) of the filtrate from (a) add a few drops of barium chloride solution followed by excess dilute hydrochloric acid.
Explanation
| Test | Observation | Inference |
| (a) C + water and filtered | Part or samples dissolves colourless filtrate salt. The filtrate is neutral to litmus | C is a mixture of a soluble salt |
| (b) The residue + dil. HCl and warmed | Effervescence occurs, a colourles, odourless gas is given off which turns lime water milky |
The filtrate is neutral. The gas is CO\(_2\). CO\(_3^{2-}\) present |
| (i) A portion from (b) + NaOH solution dropwise and in excess | A light blue precipitate insoluble in excess of the NaOH solution |
CU\(^{2+}\) are present |
| (ii) The other portion of the solution from b, saturated solution or Na\(_2\)CO\(_3\) is added | Effervescence occurs, a colourless odourless gas evolved | CO\(_2\). HCl are suspected |
| (d) To the filtrate from (a) BaCl\(_2\) and dilutes HCl were added | A white insoluble precipitate was formed |
CO\(_3^{2-}\), SO\(_3^{2-}\) SO\(_4^{2-}\) present |