Metals and nonmetals

Question 1

What are reactants?

Answer 1

Reactants are the starting substances in a chemical reaction.

Question 2

What are products?

Answer 2

Products are the substances formed as a result of a chemical reaction.

Question 3

What is an indicator?

Answer 3

An indicator is a chemical substance that changes colour when it reacts with an acid or an alkali.

Question 4

What does the pH scale measure?

Answer 4

The pH scale measures the acidity or alkalinity of a solution.

Question 5

What happens when an indicator reacts with an acid?

Answer 5

The indicator changes colour, indicating the presence of an acid.

Question 6

What happens when an indicator reacts with an alkali?

Answer 6

The indicator changes colour, indicating the presence of an alkali.

Question 7

What is the color of red litmus paper in acid?

Answer 7

Red

Question 8

What is the color of blue litmus paper in acid?

Answer 8

Red

Question 9

What is the color of bromothymol blue in acid?

Answer 9

Yellow

Question 10

What is the color of phenolphthalein in acid?

Answer 10

Colorless

Question 11

What is the color of universal indicator in acid?

Answer 11

Red, orange, yellow

Question 12

What is the color of red litmus paper in base?

Answer 12

Blue

Question 13

What is the color of blue litmus paper in base?

Answer 13

Blue

Question 14

What is the color of bromothymol blue in base?

Answer 14

Blue

Question 15

What is the color of phenolphthalein in base?

Answer 15

Pink

Question 16

What is the color of universal indicator in base?

Answer 16

Blue, purple, violet

Question 17

What is the color of red litmus paper in neutral medium?

Answer 17

Purple

Question 18

What is the color of blue litmus paper in neutral medium?

Answer 18

Purple

Question 19

What is the color of bromothymol blue in neutral medium?

Answer 19

Green

Question 20

What is the color of phenolphthalein in neutral medium?

Answer 20

Colorless

Question 21

What is the color of universal indicator in neutral medium?

Answer 21

Green

Question 22

What are examples of colored water used for pH testing?

Answer 22

Red onion water and turmeric water.

Question 23

What colors are associated with the pH scale?

Answer 23

Pink, yellow, yellow-green, red.

Question 24

What is the pH scale?

Answer 24

The pH scale is a number (0 to 14) indicating the extent of acid or base properties of a substance.

Question 25

What is the pH value of an acid solution at room temperature?

Answer 25

An acid solution has a pH value lower than 7.

Question 26

What is the pH value of an alkaline solution?

Answer 26

An alkaline solution has a pH value greater than 7.

Question 27

What is the pH value of a neutral solution?

Answer 27

A neutral solution has a pH equal to 7.

Question 28

What is a quick fact about litmus?

Answer 28

Litmus is not very accurate in low and high pH ranges.

Question 29

What is a quick fact about universal indicators?

Answer 29

Universal indicator produces accurate results across the whole pH scale.

Question 30

What does the diagram of a universal indicator show?

Answer 30

The color change of a universal indicator across the pH scale from very strong acid to very strong base.

Question 31

What is formed when a metal reacts with oxygen?

Answer 31

The product that forms is called an oxide.

Question 32

What is the composition of air in terms of oxygen?

Answer 32

Air consists of approximately 21% oxygen.

Question 33

What is a combustion reaction?

Answer 33

When a substance burns in air, it is called a combustion reaction.

Question 34

What is the general reaction formula for a metal reacting with oxygen?

Answer 34

metal + oxygen → metal oxide

Question 35

What is corrosion?

Answer 35

Corrosion is the process where the exposed surface of a metal reacts with oxygen to form metal oxide.

Question 36

What does the term 'corrosion' mean?

Answer 36

Corrosion means 'eating away'.

Question 37

Provide an example of a metal reacting with oxygen.

Answer 37

Sodium + oxygen → sodium oxide.

Question 38

Provide another example of a metal reacting with oxygen.

Answer 38

Zinc + oxygen → zinc oxide.

Question 39

Provide a third example of a metal reacting with oxygen.

Answer 39

Magnesium + oxygen → magnesium oxide.

Question 40

What are metal oxides also known as?

Answer 40

Metal oxides are also known as basic oxides.

Question 41

What is rust?

Answer 41

Rust is iron oxide that forms due to the slow chemical reaction of iron with oxygen that combines with water.

Question 42

Where does rusting occur?

Answer 42

Rust can only take place on the exposed surface of the iron.

Question 43

What metals are widely used in modern construction?

Answer 43

Iron and steel are widely used for equipment, apparatus, and structures.

Question 44

What happens to iron when it rusts?

Answer 44

When equipment or structures rust, it is weakened due to the corrosion of the iron.

Question 45

What is the main component of steel?

Answer 45

Steel consists mainly of iron.

Question 46

What is the chemical equation for rust formation?

Answer 46

4Fe + 3O2 + xH2O → 2Fe2O3·xH2O

Question 47

What is required for iron to rust?

Answer 47

Iron requires water and oxygen to rust.

Question 48

What is rust a form of?

Answer 48

Rust is a form of corrosion.

Question 49

What factors determine the rate of rusting?

Answer 49

The rate of rusting is determined by: - Salts in the water (faster near the sea) - Low pH (more acidic conditions, faster) - Impurities in iron (slower) - Amount of oxygen and other ions in contact with iron (faster).

Question 50

Why does rust occur more easily near the sea?

Answer 50

Close to the sea, rust occurs more easily and faster due to the presence of salts.

Question 51

What materials are commonly used for doors and window frames to prevent rust?

Answer 51

It is common practice to use doors and window frames made from wood or aluminium.