3.1.4 Testing For Ions Flashcards Preview

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Flashcards in 3.1.4 Testing For Ions Deck (16)
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1

Definition of Anions

Negative ions: Carbonate ions (CO3^2-), Sulfate ions (SO4^2-), Halide ions (Cl, BR, I,)

2

What do carbonate ions (CO3^2) react with?

Acid

3

Method for testing CO3^2-

>Add dilute strong acid
> Collect any gas formed and pass it through limewater

4

Positive test observations for CO3^2-

> Fizzing/ Bubbling
> Colourless gas produced
> Gas turns limewater cloudy

5

What do carbonate ions (SO4^2) react with?

Barium ions

6

Method for testing SO4^2

> Add dilute HCL acid and Barium chloride

7

Positive test observations for SO4^2-

A white precipitate is formed

8

Equation for sulfate ions

Ba^2 (AQ) + SO4^2- (AQ) --> BASO4 (AQ)

9

What do Halide ions (Cl, Br, I) react with?

Silver

10

Method for testing for hallide ions

Dissolve halide ions in water and add aqueous solution of silver nitrate
if colour hard to distinguish, ass aqueous ammonia (first dilute, then concentrated)

11

Positive test observations for Halide ions

AgCl - White precipitate, soluble in dilute Nh3
AgBr - Cream precipitate, soluble in conc NH3
AgI - Yellow precipitate, insoluble in NH3

12

Definitions of cations

Positive ions ( often containing metal ions)

13

What does Ammonium ions (NH4+) react with?

Hydroxide ions

14

Equation for testing for ammonium ions

NH4+ (AQ) + OH-(AQ) --> NH3 (AQ) + H2O (AQ)

15

Method for testing for ammonium ions (NH4+)

> Add sodium hydroxide solution and warm gently , then test any gas evolved with red litmus paper

16

Positive test observations for ammonium ions (NH4+)

NH4+ will turn red litmus paper blue and also will have a strong smell