Chemistry

Question 0

What do thermoplastics go soft when heated

Answer 0

Because of the weak forces of attraction between chains

Question 1

What is a difference between thermosets and thermoplastics

Answer 1

Thermoset stays hard when heated

Thermoplastic soften when heated

Question 2

Why do thermosets stay hard when heated

Answer 2

Because the string forces of attraction between the polymer chains

Question 3

Why are group 1 metals stored in oil

Answer 3

They react instantly with the oxygen in the air

Question 4

What are smart materials

Answer 4

Material that has properties that change shape reversible based on its surroundings

Question 5

What are thermochromic pigments

Answer 5

Change colour reversibly depending on the temperature

Question 6

What are the uses for thermochromic pigments

Answer 6

Drinks cans
Clothing
Thermometer strips

Question 7

What is temporary hard water caused by

Answer 7

Dissolved calcium carbonate or magnesium carbonate

Question 8

What is temporary hard water removed by

Answer 8

Boiling

Question 9

What type of reaction does boiling the temporary hard water cause

Answer 9

A thermal decomposition reaction

Question 10

What causes permanent hard water

Answer 10

Dissolved calcium sulfate or magnesium sulfate

Question 11

Explain how ion exchange resin colomns works

Answer 11

Hard water is passed through column which contains beads that exchange the mg2+ or ca2+ ions for sodium ions

Question 12

How is permanent hard water removed

Answer 12

Ion exchange resin or adding sodium carbonate solution

Question 13

What is a disadvantage of using ion exchange

Answer 13

Sodium ions can cause health problems

Question 14

Why do thermosets not change shape when heated

Answer 14

Strong covalent bonds between the polymer chains

Question 15

Why do thermoplastics soften and change shape when heated

Answer 15

There are weak forces of attraction between the polymer chains

Question 16

What are the processes of water purification

Answer 16

Sedimentation
Filtration
Chlorination
Screening

Question 17

What happens during sedimentation

Answer 17

Water is stored in setting tanks where large insoluble particles settle out at sludge

Question 18

What happens during filtration

Answer 18

Small insoluble particles are removed by passing through sand beds

Question 19

What is chlorination

Answer 19

Chlorine is added to kill bacteria

Question 20

What is screening

Answer 20

The water is passed through screens to remove unwanted objects like sticks litter and leaves

Question 21

What is the chemical name for CH4

Answer 21

Methane

Question 22

What is the chemical name for C2H6

Answer 22

Ethane

Question 23

What is the chemical name for C3H6

Answer 23

Propene

Question 24

What is the chemical name for C4H10

Answer 24

Butane

Question 25

What is the chemical name for C2H4

Answer 25

Ethene

Question 26

What is the chemical name for C3H6

Answer 26

Propene

Question 27

What are alkanes

Answer 27

Saturated hydro carbons that contain only C-C bonds

Question 28

What are alkenes

Answer 28

Unsaturated hydro carbons that have a c=c bond present

Question 29

What colour is sodium chloride solution

Answer 29

Colourless

Question 30

What colour is chlorine

Answer 30

Colourless

Question 31

What colour is bromine

Answer 31

Orange

Question 32

What colour is sodium bromide

Answer 32

Colourless

Question 33

What colour is iodine

Answer 33

Brown

Question 34

What colour is sodium iodide

Answer 34

Colourless

Question 35

What type of reaction is used to show the trend of a group 7 element

Answer 35

Displacement reaction

Question 36

What happens in a displacement reaction

Answer 36

The more reactive group 7 halogen displaces the less reactive group 7 halogen from its compound

Question 37

What is photochromic pigments

Answer 37

Change colour reversibly depending on the conditions

Question 38

What are the uses of photochromic pigments

Answer 38

Lenses in a pair of glasses

Question 39

What are the uses of hydrogel/polymergel

Answer 39

Nappies Clean up chemical spills Used to water plants

Question 40

What are the uses of shape memory polymers

Answer 40

Car body parts | Medical stitches

Question 41

What is and example of a shape memory alloy

Answer 41

Nitinol

Question 42

What is a use of a shape memory alloy

Answer 42

Temperature control on coffee pots

Question 43

What is hydrogel

Answer 43

Absorbs water and expands to many times it's original volume | Contracts and releases water to reduce it's original volume

Question 44

What is chromatography

Answer 44

Used to separate different coloured pigments

Question 45

What is gas chromatography

Answer 45

Used to ident the substances present and measure the about

Question 46

How do you work out the RF value

Answer 46

Distance moved by pigment divided by distance moved by solvent

Question 47

What is the metallic bond

Answer 47

The force of attraction between the positive metal ions and the sea of delocalised outer shell electrons

Question 48

Why are simple covalent molecules gases at room temperature

Answer 48

Because they have low boiling points

Question 49

Why do simple covalent molecules have low boiling points

Answer 49

Because there are weak forces of attraction between the molecules

Question 50

Why can metals conduct electricity when a voltage is applied

Answer 50

Because the sea of free outer shell electrons will move towards the positive potential

Question 51

Why are metals malleable and ductile

Answer 51

Because when a force is applied the layers can slide over each other

Question 52

Why does graphite have a high melting point

Answer 52

Because the carbon atoms are held together by strong covalent bonds

Question 53

Why won't diamond conduct electricity

Answer 53

No free electrons in the outer shell

Question 54

What are the uses of diamond

Answer 54

Cutting tools

Question 55

What are the uses of graphite

Answer 55

Lubricant and pencils

Question 56

What are the uses of carbon nanotubes

Answer 56

Micro electronics

Question 57

What is a similarity of thermosets and thermoplastics

Answer 57

Made up of long chain polymers

Question 58

What are the advantages of hard water

Answer 58

Reduces the risk of heart disease | Strengthens teeth and bones

Question 59

What are the disadvantages of hard water

Answer 59

Form limescale which makes boilers less efficient and waste energy