Chapter 10: Salts

Question 1

State the solubility of salts of the acids

Answer 1

• All nitrates are solbule
• All chlorides are soluble except for SL
• All sulfates are soluble except for CLB
• All carbonates are insoluble

Question 2

State the requirement and the reactions involved in first method (Non-SPA salts)

Answer 2

1. Insoluble metal + Acid –> salt + hydrogen gas\
2. Insoluble carbonate + acid –> salt + water + carbon dioxide
3. Insoluble base + acid –> salt + water

Requirements: One of the reactants are insoluble

Question 3

Why is excess insoluble metal, salt, base used for?

Answer 3

To ensure all the acid is used up and reacted with

Question 4

What are the steps to obtain the non-SPA salts (insoluble metal)

Answer 4

1. Excess insoluble base/metal/carbonate is added into the dilute acid. Stir until the bubbles stop
2. Filtrate to obtain the filtrate (salt)
3. Heat the filtrate until it is saturated
4. Leave the solution to cool and crystallise
5. Filter to obtain the crystals and wash with distilled water and pat dry between pieces of filter paper

Question 5

Steps to obtain non-SPA salts (insoluble carbonate)

Answer 5

1. React excess carbonate with dilute acid. Stir until bubbles stop
2. Filter to obtain the filtrate
3. Heat the filtrate until saturation
4. Let the solution cool and crystallise
5. Filter, wash and dry

Question 6

What is method 2 called and the requirements (SPA salts) + reaction

Answer 6

Method: Titration (Alkali)
Requirements: Salt is soluble, reactants are both soluble
Reaction: Alkali + acid –> salt + water

Question 7

What is method 3 called and the requirements (insoluble salts)

Answer 7

Method: Precipitation
Salts: All insoluble salts

Question 8

Describe the test for precipitation

Answer 8

1) Add soluble acid with other in a beaker. A white precipitate of (salt produced) is formed
2. Filter to obtain the white precipitate
3. Wash the white precipitate with cold, distilled water to remove impurities and leave the precipitate of the salt to dry

Question 9

Describe all the test for oxygen, hydrogen, carbon dioxide, and ammonia

Answer 9

Oxygen
Test: Place a glowing splint at the mouth of the test tube
Observation: A glowing splint is relighted / rekindled

Hydrogen
Test: Place a lighted splint at the mouth of the test tube
Observation: A lighted splint extinguishes a ´pop´ sound

Carbon dioxide
Test: Bubble gas through limewater
Observation: A white precipitate is formed

Ammonia
Test: Place a moist red litmus paper at the mouth of the test tube
Observation: Moist red litmus paper turns blue