MODULE 3 Qualitative analysis of sample X SKILLS TESTED: ORR,A&I

PROCEDURE:

Carry out the following tests on the sample X. Carefully record all observable changes. Complete the table below. Do not write a full lab report.

Tests Observations Inferences1. Add a heaped spatula load of the solid X to 10 cm3 of distilled water in a boiling tube and stir thoroughly. Keep the contents of the tube for the following tests.2. To approximately 1 cm3 of solution, add NaOH(aq) slowly until in excess.

Ion(s) possibly present

…………………………………

3. To approximately 1 cm3 of solution, add NH3 (aq) until in excess.

Ion(s) possibly present

…………………………………

4. To approximately 1 cm3 of solution, add dilute hydrochloric acid. Ion present ..………….

Write an ionic equation for the reaction

…………………………………5. Add a spatula load of Devarda’s alloy, then add NaOH (aq) and warm the mixture. Test gases evolved with moist red and blue litmus.

Acid-base nature of the gas evolved

…………………………

Formula of gas evolved ………….

Ion(s) possibly present

……………………………….

6. Add solid or aqueous FeSO4, then pour conc. H2SO4 slowly down side of tube.

Formula of compound formed

……………………………

Ion present ………………

TREATMENT OF RESULTS

1. What is the likely identity of sample X? [1]2. Write a balanced equation for the action of strong heat on the solid sample.[2]3. Suggest two reasons why the solid sample should not be strongly heated in the school laboratory.[2]4. Comment on the extent to which this sample can contaminate a potable water supply.[2]5. Explain why the solid sample has been sometimes used in pyrotechnics, for example, fireworks. [1]