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Chemistry 1, 2 + 3 > Chemistry 2: Material Choices > Flashcards

Chemistry 2: Material Choices Flashcards

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1
Q

Elastic

A

A material that returns to its original shape and size after a deforming force is removed

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2
Q

Fibres

A

A long thin thread or filament

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3
Q

Plastics

A

A compound produced by polymerisation, capable of being moulded into various shapes or drawn into filaments or used as textile fibres

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4
Q

Which property is described her material behaves

A
  • melting point
  • tensile strength
  • compressive strength
  • stiffness
  • hardness
  • density
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5
Q

Melting point

A

Temperature at which a solid changes to a liquid

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6
Q

Tensile strength

A

A measure of the resistance of a solid to pulling or stretching a force

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7
Q

Compressive strength

A

A measure of resistance to squeezing or crushing forces

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8
Q

Stiffness

A

A measure of the resistance of a solid to bending forces

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9
Q

Hardness

A

A measure of resistance to change the shape of a solid, four example by scratching or by impact

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10
Q

Density

A

The mass of the substance per unit volume

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11
Q

What is density measured in

A

g/cm3 or kg/m3

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12
Q

How is the effectiveness and durability of a product depend on the materials used to make it

A
  • some materials can be drawn into thin filaments with greater tensile strength. They can be spun into fibres and woven into cloth
  • ropes are made by winding fibres together. The more there wound, the greater the strength
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13
Q

What are the properties of rubber

A
  • and elastic material that bounces back when a force is removed
  • different types of rubber have different compressive strength and hardness
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14
Q

How do we treat errors

A
  • A single result may vary, so repeats are needed
  • A result which is very different might be an outlier – an incorrect result
  • calculating the mean (average) is a good way to estimate the true value
  • Errors in measurement produce variations in data
  • outliers can only be discarded if an error occurred in the measurement
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15
Q

True value

A

A theoretically accurate value that could be found if measurements could be made without errors

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16
Q

How do we find the true value

A
  • many measurements need to be taken to find the true value
  • The range is the smallest to largest result, excluding outliers
  • we can never be sure if a set of measurements gives the true value
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17
Q

Materials we use that are chemicals or mixtures of chemicals

A
  • metals are chemicals which are shiny, malleable and electric conductors
  • ceramics include play, glasses cement. They are hard and strong
  • polymers are large molecules are used to make rubbers, plastics and fibres
  • concrete is a mixture of sand and cement
  • bronze is a mixture of copper and tin
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18
Q

Metals

A

A group of materials (elements or mixtures of elements) with broadly similar properties, such as being hard and shiny, able to conduct heat in that electricity able to form thin sheets (malleable) and wires (ductile)

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19
Q

Ceramics

A

Nonmetallic solids made by heating and cooling a material, such as clay to make pottery

20
Q

Malleable

A

Able to be beaten into a thin sheet; a common property of metals

21
Q

Polymers

A

Large molecule made up of a chain smaller molecules (monomers)

22
Q

Natural materials

A

Materials made from plant and animal products. For example cotton and paper

23
Q

Where are the natural raw materials extracted from

A

The earths crust are limestone, iron ore and crude oil

24
Q

Crude oil

A

Black substance extracted from the earth, from which petrol are many other products are made

25
Q

Synthetic materials

A

Material manufactured from chemicals and are alternatives to natural materials from living things

26
Q

Why have synthetic materials replaced natural materials?

A
  • some natural materials are in short supply
  • they can be designed to give particular properties
  • they are often cheaper and can be made in the quantity
27
Q

What is crude oil made of

A

Crude oil (petroleum) is a mixture of thousands of hydrocarbons

28
Q

hydrocarbon

A

Compound containing only carbon and hydrogen

29
Q

What are hydrocarbons

A
  • most hydrocarbons from crude oil are used as fuels

* when fuels burn in oxygen, carbon dioxide and water are made

30
Q

What happens if you burn a fuel like methane

A

is a chemical reaction so atoms are rearranged into new products

31
Q

Give the word equation and describe what happens when propane reacts with oxygen

A

Propane + oxygen -> carbon dioxide + water

  • carbon from propane joins from the oxygen atoms in the oxygen to form carbon dioxide
  • hydrogen atoms in the propane reacts with the oxygen’s oxygen atom to form water
32
Q

What does crude oil consist of and how long are they

A
  • Crude oil mainly consists mainly of enough mixture of hydrocarbons, which are chain molecules of varying length up to 100 carbon atoms long.
  • As crude oil is a mixture, it’s composition varies from place to place
33
Q

What percentage of crude is used for fuels and synthetics

A
  • nearly 90% of crude oil is used as fuels
  • around 3% of crude oil, mainly smaller hydrocarbon molecules, is used to synthesise other chemicals. Examples of synthesised chemicals from oil are ethanol and plastics
34
Q

How is crude oil separated

A

Fractional distillation

35
Q

Describe the process of fractional distillation

A
  1. The oil is heated up which turns it into gases
  2. The Distillation tower gets cooler as it gets higher
  3. Gas molecules condense into liquids when they cool
  4. Liquids with similar boiling points collect together. These are called fractions
36
Q

Fractional distillation

A

Process that separates the hydrocarbons in crude oil according to the size of their molecules

37
Q

How are each substance is affected at each fraction

A
  • hydrocarbons in each fraction ha a range of temperatures
  • molecule chain lengths are similar sizes within each fraction
  • the smaller the molecule chain length, the lower the boiling point
  • the smaller the molecule chain length, the smaller the forces between molecules
38
Q

How does attractive forces vary between molecules

A
  • attractive forces exist between molecules in crude oil, holding them together
  • as the hydrocarbon chain length increases, the force between these larger molecules increases
  • larger molecules need more energy to break them out of a liquid to form a gas, so have higher boiling points
39
Q

Polymer

A

Large molecule made up of a chain smaller molecules (monomers)

40
Q

Monomers

A

Small molecules that become chemically bonded to one another to form a polymer chain

41
Q

How is a polymer made

A

By polymerisation

42
Q

Polymerisation

A

Chemical process tags combines monomers to form a polymer

43
Q

How have polymers been replaced and give examples

A
  • polymers with better properties mean some older materials have been replaced
  • for example plastic bucked and carbon fibre tennis rackets
44
Q

Give an example of what a monomers is and what it is used for

A

Ethene is a monomers used to make polyethylene

45
Q

What are the properties of PET

A
  • PET (polyethylenetetraphthalate) is a polymer used to make drinks bottles.
  • PET is clear, strong, has a low density and doesn’t shatter
  • this makes it a superior material to glass
46
Q

How can new polymers be made

A
  • polymer chains can be altered by replacing hydrogen atoms with other atoms or groups of atoms
  • each new polymer has its own set of properties and uses
  • materials such as Kevlar have advantages over alternatives, but can also have disadvantages
  • material choice will depend on comparing properties for different jobs, with cost of being a factor
47
Q

Name some materials and the properties

A
  • rubber is used for car tyres because it is hard and elastic
  • fibres are used to weave cloth into clothes
  • plastics keep their shape when moulded into objects like washing up bowls

Chemistry 1, 2 + 3 (3 decks)

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