Test For Anions (chpt. 6)

Question 1

Chemical reaction

Answer 1

When elements react together to form a compound
A new substance is always formed

Question 2

Evidence of chemical reactions

Answer 2

Colour change
Temperature change
Light or sound given off
Effervescence (gas given off)

Question 3

Anions

Answer 3

Negative ions

Question 4

Law of conservation of mass

Answer 4

States that the total mass of the products of a chemical reaction is same as the total mass of the reactants

Question 5

Law of conservation of matter

Answer 5

States that in any chemical reaction, matter is neither created nor destroyed but merely changes from one form into another

Question 6

Test for chloride ions

Answer 6

Dissolve the salt in deionised water to obtain a clear solution
Add a few drops of AgNO3 (silver nitrate)
The clear solution will turn cloudy and a white precipitate will form that is soluble in dilute ammonia solution

Question 7

Test for sulfate or sulfite ions

Answer 7

• Barium chloride BaCl2
↳ white precipitate forms

• add dilute HCl
↳ remains = sulfate
↳ dissolves = sulfite

Question 8

Test for nitrate ions

Answer 8

Brown ring test

• freshly prepared iron sulfate solution
• concentrated sulfuric acid
→ a brown ring will form at the junction of the two liquids

Question 9

Test for phosphate ions

Answer 9

• ammonium molybdate
• concentrated nitric acid (using dropper)
• place solution in warm water
• yellow precipitate forms
↳ phosphate ions are present

Question 10

Test for carbonate or hydrogencarbonate ions

Answer 10

• add dilute HCl
↳ fizzing

• add magnesium sulfate
↳ white precipitate forms = carbonate
↳ no precipitate forms = hydrogencarbonate