Anions: Test and characteristics of Anions

Test for Anions,

Identification of gases e.g CO₂, SO₂ and O₂.

Characteristics test for anions e.g SO₄^2-,SO₃^2-,CO₃^2-,NO^-3, Cl^–, etc.

The anions are negatively change ions examples of anions are SO₄^2-,SO₃^2-,CO₃²-,S^2- etc.

Identifications of gases:

H2	It gives a ‘pop’ sound when the gas is contact with a lighted splint.
O2	It rekindles a glowing splint.
CO2	It is colourless and odourless. It turns lime water milky.
Cl2	A green wish yellow gas, it turns moist iodide paper black.
SO2	Colourless gas with irritating smell. It turns damp blue litmus paper to red. That is acidic gas.

EVALUATION

1. State two (2)  examples of anions with their gases.
2. Identify Cl₂ and NH₃ gases.

GENERAL EVALUATION

1. Give the common reagents for confirmatory test of anions
2. State how you would confirm/test for NO^3-
3. Name three gases that are colourless and acidic to litmus.
4. Sodium chloride and silver trioxonitrate(V) crystals are separately soluble in water to give colourless solutions. Explain what happens when their solutions are mixed together.

READING ASSIGNMENT

School Chemstry by O.Y Ababio pages 165 – 183

Practical Chemistry by R. I Makanjuola pages 27-33.

Practical Chemistry for Schools and Colleges by Godwin O. Ojokuku pages 30 – 98.

WEEKEND ASSIGNMENT

1. Brown ring test is used to confirm (a) S^2- (b)NO^3- (c) SO₄^2- (d) SO₃^2-
2. The presence of SO₃^2- change the colour of acidified K₂Cr₂)⁷ from (a) green to red    (b) purple to colourless  (c) orange to green  (d) green to orange
3. A greenish yellow gas that change moist iodide paper black is (a) Cl₂   (b) SO₂ (c) H₂  (d) O₂
4. Sometimes in the presence of  conc HsSO₄, copper turning and heat NO^3- gives (a) brown ring reaction  (b) pure brown fume   (c ) reddish brown   (d) effervescence        
5. The gas that turns lime water milky is (a) H₂ (b) SO₂ (c) NH₃ (d) CO₂.

THEORY

1. State the colour of these solutions a. KMnO₄ b. K₂Cr₂O₃ c. HOBr d. CuSO₄.5H₂O e. Ca(OH)₂
2. Carry out the following exercises on sample K. add about 10cm3 of distilled water to K in a test tube. Divide the solution into four.
3. To the 1^st portion add NaOH  drop wise and in excess.
4. To the 2^nd portion add NH₃ solution drop wise and then in excess.
5. To the 3^rd portion, add it drops of BaCl2 follow by the addition of dil HCl
6. To the 4^th portion, add dil HCl follow by the addition of BaCl₂.

Record your observation and inferences then name the salt K.