2f-Acids, bases and salt preparations

Question 1

Question: What is an acid?\

Answer 1

Answer: An acid is a substance that releases hydrogen ions (H⁺) when dissolved in water. Acids have a pH of less than 7.

Question 2

Question: What is an alkali?

Answer 2

Answer: An alkali is a soluble base that releases hydroxide ions (OH⁻) when dissolved in water. Alkalis have a pH greater than 7.

Question 3

Question: What is a neutral solution?

Answer 3

Answer: A neutral solution has a pH of 7 and contains equal concentrations of H⁺ and OH⁻ ions.

Question 4

Question: What is the pH scale?

Answer 4

Answer: The pH scale measures how acidic or alkaline a solution is, ranging from 0 (strong acid) to 14 (strong alkali), with 7 being neutral.

Question 5

Question: What is a salt?

Answer 5

Answer: A salt is a compound formed when the hydrogen ions (H⁺) in an acid are replaced by metal ions or ammonium ions.

Question 6

Question: What are the general reactions of acids?

Answer 6

Answer:

Acid + Metal → Salt + Hydrogen

Acid + Base → Salt + Water

Acid + Carbonate → Salt + Water + Carbon dioxide

Question 7

Question: Give examples of acids and their corresponding salts.

Answer 7

Answer:

Hydrochloric acid (HCl): Forms chlorides (e.g., Sodium chloride - NaCl)

Sulfuric acid (H₂SO₄): Forms sulfates (e.g., Copper sulfate - CuSO₄)

Nitric acid (HNO₃): Forms nitrates (e.g., Potassium nitrate - KNO₃)

Question 8

Question: How do you prepare a soluble salt from an acid and an insoluble base?

Answer 8

Answer:

Add the base to the acid until no more reacts.

Filter the solution to remove excess base.

Heat the solution to evaporate water and crystallize the salt.

Question 9

Question: What is titration, and how is it used to make a salt?

Answer 9

Answer: Titration is used to neutralize an acid with an alkali. The exact amount of alkali needed is measured, and the solution is evaporated to form crystals of the salt.

Question 10

Question: How do you test for hydrogen and carbon dioxide gases?

Answer 10

Answer:

Hydrogen: A lit splint produces a squeaky pop.

Carbon dioxide: Turns limewater milky.

Question 11

Practical: Preparing Copper Sulfate Crystals

Method:

Answer 11

Add copper oxide to warm sulfuric acid until no more dissolves.

Filter the solution to remove excess copper oxide.

Heat the solution gently and leave it to cool, allowing blue copper sulfate crystals to form.

Question 12

Practical: Preparing Copper Sulfate Crystals
Results & conclusion

Answer 12

Result:

Blue copper sulfate crystals are formed.

Conclusion:

The reaction between copper oxide and sulfuric acid produces copper sulfate and water.