Chemical analysis Flashcards

1
Q

What is a pure substance?

A

something that only contains one compound or element

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2
Q

How can you test the purity of a substance?

A
  • chemically pure substance will melt or boil at a specific temperature
  • measure the melting or boiling point of a sample and comparing it to that of a pure substance
  • closer your measured value is to the actual melting or boiling point, the purer it is
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3
Q

What are formulations?

A

useful mixtures with a precise purpose that are made by a following ‘formula. Each component in it is present in a measured quantity, and contributes to the properties of the formulation so that it meets its required function

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4
Q

What is the formulation paint made of?

A
  • pigment
  • solvent
  • binder
  • additives
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5
Q

What are formulations used for?

A
  • pharmaceutical industry- formulations of pills
  • cleaning products, fuels, cosmetics, metal alloys and food and drink
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6
Q

What are the two different phases of chromatography?

A
  • mobile phase- molecules can move (liquid or gas)
  • stationary phase- where molecules can’t move (solid or really thick liquid)
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7
Q

What are some examples of greenhouse gases?

A
  • carbon dioxide
  • methane
  • water vapour
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8
Q

Why are greenhouse gases important for the earths atmospheres?

A

acts as an insulating layer to allow the earth to be warm enough to support life

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9
Q

What is the greenhouse effect?

A

Greenhouse gases absorb long wavelength radiation that gets reflected back off the earth. Then they re-radiate it in all directions. As the long wavelength radiation is thermal radiation it warms the earths surface

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10
Q

What human activities impact the amount of greenhouse gases in the atmosphere?

A
  • deforestation
  • burning fossil fuels
  • agriculture- farm animals produce methane through digestion
  • creating waste
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11
Q

What are the consequences of climate change?

A
  • can lead to polar ice caps melting- causing a rise in sea levels, increased flooding in coastal area and coastal erosion
  • changes in rainfall patterns may cause some regions to get too much or too little water- may affect regions ability to produce food
  • the frequency and severity of storms may increase
  • changes in temperature and the amount of water available in a habitat may affect wild species, leading to differences in their distribution
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12
Q

What are carbon footprints?

A

a measure of the amount of carbon dioxide and other greenhouse gases released over the full life cycle of something

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12
Q

Why is measuring carbon footprints difficult?

A

because there are so many different factors to consider:
emissions from sourcing raw materials
- production of the product
- use of product
- disposal of product

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13
Q

Why are carbon footprints useful?

A

helps identify the emitters so people can avoid them in the future

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14
Q

What are some ways of reducing carbon footprints?

A
  • using renewable energy sources or nuclear energy instead of fossil fuels
  • Using more efficient processes could converse energy and cut waste
  • government could tax companies or individuals based on the amount of greenhouse gases they emit
  • Government can also put a cap on emissions of all greenhouse gases that companies make
  • technology that captures CO2 produced by burning fossil fuels before it’s released into the atmosphere- stored deep underground in cracks of rocks
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15
Q

Why is reducing carbon footprints difficult?

A
  • still a lot of work to be done on alternative technologies that lower CO2 emissions
  • may impact the economic growth of some communities
  • Not everyone is onboard so it is difficult to make international agreements
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16
Q

What is a ceramic?

A

a non-metal solid with a high melting point that aren’t made from carbon-based compounds

17
Q

What are some examples of ceramics?

A
  • clay
  • glass
18
Q

What are clay’s properties?

A
  • soft material so can be moulded
    -high melting point
  • fired at high temperatures and hardens
19
Q

What is clay used to make?

A

pottery and bricks

20
Q

What are the properties of glass?

A
  • generally transparent
  • moulded when hot
  • brittle when thin
21
Q

What are two types of glass?

A
  • soda-lime glass
  • borosilicate glass
22
Q

How is soda-lime glass made?

A

heating a mixture of limestone, sand and sodium carbonate until it melts and when it cools it comes out as glass

23
Q

How is borosilicate glass made?

A

By heating a mixture of sand and boron trioxide

24
Q

What are composites made of?

A

One material embedded in another. Fibres of fragments of a material (reinforcement) surrounded by a matrix acting as a binder

25
Q

What are some different examples of composites?

A
  • fibreglass
  • carbon fibre
  • concrete
  • wood
26
Q

What are the properties of fibreglass, what is it used for and what is it made up of?

A
  • Consists of fibres of glass embedded in a matrix made of polymer.
  • low density
  • very strong
    -used for- skis, boats and surfboards
27
Q

What are the properties of carbon fibre, what is it used for and what is it made up of?

A
  • consists of carbon fibres embedded in a matrix made of polymer.
  • very strong
  • light
  • used in aerospace and sports car manufacturing
28
Q

What are the properties of concrete, what is it used for and what is it made up of?

A
  • made from aggregate embedded in cement
  • very strong
  • used for building materials
29
Q

What is wood made up of?

A

natural composite of cellulose fibres held together by an organic polymer matrix

30
Q

What are some examples of the properties of poly(ethene) being affected by the catalyst that was used?

A
  • LD poly(ethene)- made from ethene at a moderate temperature under a high pressure- flexible and used for bags and bottles
  • HD poly(ethene)- also made from ethene but at a lower temperature and pressure with a catalyst- more rigid and is used for water tanks and drain pipes
31
Q

What are some examples of the properties of polymers being affected by the bonding between the polymer chains?

A
  • Thermosoftening polymers- contain individual polymer chains entwined together with weak forces between the chains- you can melt and remould these plastics
  • Thermosetting polymers- contain monomers that can form cross-links between the polymer chains, holding the chains together in a solid structure- don’t soften when heated
32
Q

What are the properties of ceramics?

A
  • insulators of heat and electricity
  • brittle
  • stiff
33
Q

What are the properties of polymers?

A
  • insulators of heat and electricity
  • flexible
  • easily moulded
34
Q

What are the properties of metals?

A
  • malleable
  • good conductors of heat and electricity
  • ductile (can be drawn into wires)
  • shiny and stiff
35
Q

What do the properties of composites depend on?

A

the matrix/binder and the reinforcement used to make them

36
Q

What are some examples of alloys and what are they made up of?

A
  • bronze= copper+tin
  • brass= copper+zinc
  • gold alloys= gold and metals such as zinc, copper or silver
  • aluminium alloys
37
Q

What is corrosion?

A

where metals react with substances in their environment and are gradually destroyed

38
Q

What is the corrosion of iron called?

A

rusting

39
Q

What is rust?

A

the compound hydrated iron (III) oxide

40
Q

What is the word equation for the formation of rust?

A

iron+oxygen+water—> hydrated iron (III) oxide