Ch.8 Reactivity Trends

Question 1

Test for Carbonate ions (CO3) 2-

Answer 1

1) Add dilute HCl acid
carbonate + acid-> carbondioxide + water

Positive result = carbon dioxide released ->test by bubbling gas through limewater = goes cloudy

Question 2

Test for sulfate ions (SO4)2-

Answer 2

1) Add HCl
2) Then Barium chloride (BaCl2)
Positive result = white precipitate (barium sulfate)

Question 3

Test for Halide ions

Answer 3

1) Add nitric acid
2) Then silver nitrate solution
Positive results: precipitates
silver CHLORIDE = WHITE
silver BROMIDE = CREAM
silver IODIDE = YELLOW

Question 4

Testing solubility of halides to tell them apart

Answer 4

Dilute NH3:
AgCl dissolves but AgBr and AgI do not
Conc NH3
AgCl and AgBr dissolve but AgI does not

Question 5

Test for ammonium ions (NH4+)

Answer 5

-add NaOH
-warm the mixture
Pos = ammonia gas (NH3) given out -> used damp red litmus paper -> turns blue

Question 6

Order of qualitative tests

Answer 6

1) Carbonate
2) Sulfate
3) Halides

this is to avoid false positives

Question 7

How to get rid of any lurking anions

Answer 7

add dilute acid