Chemistry Acids, bases, and salts

Question 1

Mention all 3 of neutralisation reactions

Answer 1

• acid + base = salt + water
• acid + metal = salt + hydrogen
• acid + metal carbonate = salt + water + carbon dioxide

Question 2

Mention the common alkalis (4)

Answer 2

• sodium hydroxide solution
• potassium hydroxide solution
• calcium hydroxide solution
• ammonia solution (ammonium hydroxide)

Question 3

Mention common bases (2)

Answer 3

• calcium oxide

- magnesium oxide

Question 4

Difference of alkalis and base

Answer 4

• All alkalis are base but not all base are alkalis
• Base does not dissolve in water, bases that dissolves in water are alkalis.
• Base neutralize acid, alkali releases OH- ions and accepts a proton

Question 5

Examples of indicators and it’s colors in acidic, neutral and alkaline

Answer 5

• Red litmus: Red in acidic, red in neutral, blue in alkaline
• Blue litmus: Red in acidic, blue in neutral, blue in alkaline
• Methyl orange: Red in acidic, yellow in neutral, yellow in alkaline
• Litmus: Red in acidic, purple in neutral, blue in alkalis
• Universal indicator: Red in strongly acidic, green in neutral, violet in strongly alkaline

Question 6

Difference of acids and bases with protons

Answer 6

Acids are proton donors and bases are proton acceptors

Question 7

Meaning of weak and strong acid

Answer 7

• Strong acid completely dissociates to release H+ ions in aqueous solution.
• Weak acid partially dissociates to release H+ ions in aqueous solution.

Question 8

Meaning of weak and strong base

Answer 8

• Strong base fully dissociates to release OH- ions in aqueous solution.
• Weak base partially dissociates to release OH- ions in aqueous solution.

Question 9

What do acid and base release in aqueous solution

Answer 9

Acid releases H+ ions, base releases OH- ions in aqueous solution

Question 10

What does concentrated and dilute means

Answer 10

When dissolved in water, large amount of water is dilute while small amount of water is concentrated

Question 11

What is pH scale

Answer 11

Measures the acidity and alkalinity of a solution, H+ or the OH- ion concentrations present

Question 12

Why is it important to control acidity in soil

Answer 12

If the pH of soil is too low, or too acidic, this would mean the plants would be unable to grow in these acidic soils. Farmers use calcium oxide to neutralize.

Question 13

Explain oxides

Answer 13

Oxides has non-metal oxide and metal oxide. Non-metal oxide has acidic properties and can be neutral oxide that does not neutralize any acid or base. Metal oxide has basic properties and can be amphoteric that neutralize both acid and base.

Question 14

What are amphoteric

Answer 14

Neutralize both acid and bases to form salt and water.

Question 15

What can we use to make an oxide

Answer 15

Sulfur

Question 16

Prepare salts from insoluble base

Answer 16

Excess base is added to the acid, filter our to remove any unreacted base that’s been added, heat solution or leave in warm place to evaporate the water, allowing crystals of salts to form

Question 17

Prepare salts from soluble base

Answer 17

Use an acid-base titration to find the exact volume of the soluble base that reacts with the acid, mix these correct proportions which will produce salt and water only, warm solution to evaporate the water and leave crystals of salt

Question 18

Suggest the method of making salt where reactants are soluble

Answer 18

Titration

Question 19

Suggest the method of making salt where the base is insoluble

Answer 19

Add excess of base to ensure complete neutralization