Ch - 11 (Acids and Bases)

Question 1

What happens when acids are added to water?

Answer 1

Form positively charged hydrogen ions. (H+)

Question 2

What makes a solution acidic?

Answer 2

Presence of H+ ions.

Question 3

Give a word equation of acids reacting with metals?

Answer 3

Acid + Metal –> Salt + Hydrogen

Question 4

Which metals in the reactivity series will react with dilute acids?

Answer 4

Metals above hydrogen

Question 5

What can act as bases?

Answer 5

• Metal oxides
• Hydroxides (alkalis)

Question 6

Give a word equation of acid reacting with base.

Answer 6

Acid + base –> Salt + water

Question 7

Give an equation of the acid reacting with a metal carbonate.

Answer 7

Acid+ metal –> salt + carbon dioxide + water

Question 8

What is one common indicator?

Answer 8

Litmus extracted from lichens

Question 9

What are synthetic indicators?

Answer 9

Organic compounds that are sensitive to changes in acidity and appear different colours in acids and alkalis.

Question 10

What are 2 synthetic indicators frequently used in acid - alkali titrations?

Answer 10

Thymolphthalein and methyl orange

Question 11

What are synthetic indicators used for?

Answer 11

To show the endpoint in titrations as they have a very sharp change of colour when an acid has been neutralised by an alkali or vice versa.

Question 12

Is litmus suitable for tritration? why or why not?

Answer 12

colour change is not so sharp, colour in neutral solution makes it difficult

Question 13

What pH does a base have?

Answer 13

Above 7

Question 14

What is a base?

Answer 14

water soluble referred to as an alkali

Question 15

In basic (alkaline) what colour do the following change into:
- red litmus paper
- methyl orange
-thymolphthalein

Answer 15

• red litmus paper: blue
• methyl orange: yellow
  -thymolphthalein: blue

Question 16

What form are bases of metals?

Answer 16

Oxides or hydroxides

Question 17

What happens when alkalis are added to water?

Answer 17

Form negative (OH-) ions

Question 18

What makes a solution an alkali?

Answer 18

Presence of OH- ions

Question 19

Give a word equation of what happens when acid reacts with bases?

Answer 19

Acid + base –> salt + water

Question 20

What happens when acids are added to water?

Answer 20

Form positively charged H+ ions (acidic)

Question 21

What happens when alkalis are added to water?

Answer 21

Forms negative OH- ions (alkali)

Question 22

When does a neutralisation reaction take place?

Answer 22

When acid reacts with an alkali

Question 23

What happens when substances react together in a neutralisation reaction?

Answer 23

H+ ions reacts with OH- ions to produce water

Question 24

What is the net ionic equation of acid - alkali neautralisation reaction?

Answer 24

H+ + OH- –> H2O

Question 25

What is the pH of all acids?

Answer 25

Below 7

Question 26

What is the pH of all alkalis?

Answer 26

Above 7

Question 27

What does it mean when we have more hydrogen ions?

Answer 27

Stronger the acid but lower the pH

Question 28

What does it mean when we have a stronger concentration of hydroxide ions?

Answer 28

Higher pH

Question 29

How is the Ph scale calibrated?

Answer 29

Logarithmic, change of 1 on the scale represents a change in concentration by a factor of 10

Question 30

Define a universal indicator.

Answer 30

A universal indicator is a mixture of different indicators which is used to measure pH.

Question 31

Define acids

Answer 31

- Proton donors - Produce H+ protons

Question 32

Define bases.

Answer 32

- Proton acceptor

Question 33

How can an acid be weak or strong?

Answer 33

depending on how many H+ ions they produce

Question 34

What happens to strong acids?

Answer 34

Completely dissociate (ionise) in water, producing very low pH

Question 35

What are examples of strong acids?

Answer 35

Hydrochloric acid, Sulfuric acids, nitric acid

Question 36

What is an example of a weak acid?

Answer 36

Ethanoic acid (CH3COOH) - Vinegar

Question 37

What happens to weak acids in water?

Answer 37

Partially dissociate (ionise) in water and produce pH value closer to the middle lf pH scale below 7

Question 38

What does a concentrated solution mean?

Answer 38

An acid that contains a higher no. of acid molecules

Question 39

Define oxides.

Answer 39

Compounds made from one or more atoms of oxygen combined with another element.

Question 40

How can oxides be classified?

Answer 40

Based on their acid - base characteristic.

Question 41

What are the difference in properties of acidic and basic oxides?

Answer 41

- Difference in their pH depends on the bonding with a metal or non - metal - Metallic character of the element influences the acidic or basic behaviour

Question 42

What are properties of acidic oxides?

Answer 42

- Non - metal combines with oxygen - React with bases to form salt and water - When dissolved in H2O, they produce an acidic solution with low pH Example - CO2, SO2, NO2

Question 43

What are the properties of basic oxides?

Answer 43

- Metal element combines with oxygen - React with acids to form salt and water - When dissolved in H2O, they produce a basic solution with a High pH. Example: CuO, CaO

Question 44

what are neutral oxides?

Answer 44

- Do not react with acids or bases - Example: N2O, NO and CO

Question 45

Define amphoteric oxides.

Answer 45

- Curious group of oxides tht behave both acidic and basic, depending on reactant being an acid or base

Question 46

What are properties of an amphoteric oxide?

Answer 46

- Salt and water is formed - common example: ZnO, Al2O3 - Hydroxides are also amphoteric