Acids, Bases and Salts

Question 1

What is an acid?

Answer 1

A substance that dissolves in water to produce hydrogen ions (H+). This solution:

• Contains an excess of H+ ions
• Turns litmus red
• Has a pH lower than 7

Question 2

What is an alkaline?

Answer 2

A substance that dissolves in water to produce hydroxide ions (OH-). This solution:

• Contains an excess of OH- ions
• Turns litmus blue
• Has a pH higher than 7

Question 3

Indicator

Answer 3

A indicator allows to detect whether a solution is acidic or not. (litmus, methyl orange)

Question 4

Indicator (Litmus) Color change

Answer 4

Acid - Turns blue litmus red

Base - Turns red litmus back to blue

Question 5

Universal indicator

Answer 5

a mixture of dyes that changes color gradually over a range of pH and is used (especially as indicator paper) in testing for acids and alkalis

Question 6

pH scale rules

Answer 6

• Acids have a pH less than 7
• The more acidic a solution the lower its pH
• Neutral substances such as pure water has a pH of 7
• Alkalis have a pH higher than 7

Question 7

Corrosive

Answer 7

A corrosive material is a highly reactive substance that causes obvious damage to living tissue.

Question 8

The characteristics of oxides

Answer 8

• Non metals generally form acidic oxides that dissolve in water to form acidic solutions
• Metals form oxides that are solids. If they dissolve in water, these oxides give alkaline solutions. These metal oxides neutralize acids and basic oxides

Question 9

Amphoteric hydroxide

Answer 9

A hydroxide or metal oxide that reacts with both acid and an alkali to give salt and water.

Question 10

Neutralization

Answer 10

A neutralization reaction occurs when a salt is formed during an reaction. equation - acid + base = salt + water

Question 11

Base

Answer 11

A substance that reacts with acid to form salt and water only

Question 12

Alkali

Answer 12

A base that is soluble in water. They are mostly in aqueous form.

Question 13

Common alkalis

Answer 13

• Sodium hydroxide (NaOH)
• Potassium hydroxide (KOH)
• Calcium hydroxide (Ca(OH)₂)
• Ammonium hydroxide (NH₄OH)

Question 14

Base Characteristics

Answer 14

• Neutralizes acids to give salt and water only
• are the oxides and hydroxides of metals
• are mainly insoluble in water

Question 15

Alkalis Characteristics

Answer 15

• Feel soapy to the skin
• turn litmus blue
• gives solution with pH greater than 7
• gives solutions that contain OH- ions

Question 16

Antacids examples

Answer 16

• Magnesium oxide (MgO)
• Magnesium hydroxide (Mg(OH)2)
• Sodium carbonate (Na2CO3)
• Sodium hydrogencarbonate (NaHCO3)
• Calcium carbonate (CaCO3)
• magnesium carbonate (MgCO3)

Question 17

Salt

Answer 17

A compound made from a acid when a metal takes the place of hydrogen in the acid

Question 18

Acid with metal

Answer 18

Metal + Acid = salt +hydrogen

Question 19

Salt made in hydrochloric acid

Answer 19

Salt made in hydrochloric acid is chloride

Question 20

Salt made in nitric acid

Answer 20

Salt made in nitric acid is nitrate

Question 21

Salt made in Sulfuric acid

Answer 21

Salt made in Sulfuric acid is sulfate

Question 22

Salt made in Ethanoic acid

Answer 22

Salt made in Ethanoic acid is ethanoate

Question 23

Acid with carbonate

Answer 23

Acid + metal carbonate = salt + water + CO2

Question 24

Test for carbonates using acids

Answer 24

Carbon dioxide gas bubbles if carbonate ions are present.

Question 25

Precipitation

Answer 25

The sudden formation of a solid, either:

• when two solutions are mixed
• When gas is bubbled into a solution

Question 26

Acid with base

Answer 26

Acid + Base = Salt + Water