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Chemistry > Chem Analysis and Using Recourses > Flashcards

Chem Analysis and Using Recourses Flashcards

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1
Q

Pure substances

A
  • single element/ compound with no mixed substances

- to see if pure they should boil at exact boiling point (eg, water at 100)

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2
Q

Formulations

A
  • mixture designed for a useful product

- carefully measure quantities for desired properties

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3
Q

Examples of formulations

A
  • fuels
  • cleaning agents
  • paints
  • medicines
  • alloys
  • fertilisers
  • food
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4
Q

Chromatography definition

A
  • the separation of mixtures that gives information to indentify substances
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5
Q

Rf =

A

Distance moved by substance / distance moved by solvent

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6
Q

Mobile and stationary phase

A
  • molecules can move (liquid/ gas) and they are molecules with higher solubility and less attraction to the paper
  • molecules that can’t move (thick liquid/ solid)
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7
Q

How to test for pure substances with chromatography

A
  • pure sample run it along the tested and if Rf value is = the tested is pure
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8
Q

Tests for gases

A
  • hydrogen, burning splint held at open end of tube makes ‘squeaky pop’ sound
  • oxygen, relights a glowing splint
  • Carbon Dioxide, passed through limewater it turns cloudy
  • chlorine, damp litmus paper bleaches
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9
Q

Flame tests reasons

A

To identify cations

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10
Q

Results of the flame test

A
  • lithium, crimson-red
  • sodium, yellow
  • calcium, orange- red
  • potassium, lilac
  • copper, green
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11
Q

Reasons for metal hydroxide precipitate test

A

To identify cations

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12
Q

Precipitate test results

A
  • Calcium, White
  • copper, blue
  • Iron (II), green
  • Iron (III), brown
  • Aluminium, White -> colourless
  • magnesium, white
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13
Q

Carbonates reaction

A
  • react with dilute acid to form CO2 gas
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14
Q

Halide reactions

A
  • produce precipitates with silver nitrate in dilute acid
  • silver chloride, white
  • silver bromide, cream
  • silver iodide, yellow
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15
Q

Instrumental methods + advantages

A
  • how compounds detected

- sensitive (detect small amounts), fast, accurate

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16
Q

Flame emission spectroscopy

A
  • example of instrumental method
  • metal ions analysis
  • put through and light travels through spectroscope
  • output line identifies ion and can measure conc
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17
Q

Proportion of gases in the atmosphere

A
  • 80% nitrogen
  • 20% oxygen
  • small properties of CO2, water vapour and noble gases
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18
Q

Evolution of the atmosphere

A
  • started 4.6 billion years ago, Early on there was intense volcanic activity that released gases plus water vapour
    – atmosphere mostly CO2, water vapour condenses to form oceans. Volcanoes also produce nitrogen
    – the oceans dissolved CO2 in water and carbonate will precipitated producing sediments reducing CO2 in yet
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19
Q

How Oxygen increase during evolution

A

– Algae first produce oxygen through photosynthesis plus plants produced more
– as they involved oxygen levels slowlt increase alone evolution of animals

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20
Q

Greenhouse gases

A

– Maintain temperature high
– include methane, water vapour, CO2
– allow short wavelengths from sun but absorb longer wavelengths from earth

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21
Q

Reasons for climate change

A

– Scientist believe it is from human activity

– but, difficult to model complex systems at least to simplified models and speculation

22
Q

Consequences of climate change

A

– Polar caps melting leading to rise of sea levels
– change of rainfall patterns
– increase severity of storms
– amount of water changes

23
Q

Carbon footprint

A

Total amount of CO2 or other greenhouse gases emitted in lifecycle of a product

24
Q

Ways to reduce carbon footprint

A

– Renewable energy
– tax emissions
– cap emissions
– calturw CO2

25
Q

Why the reduction of carbon footprint is difficult

A

– Tax Impax economy
– not everyone on board
– change lifestyles

26
Q

What are atmospheric pollutants

A

– Combustion of fuels (coal, carbon, hydrogen)

– incomplete combustion (soot)

27
Q

Properties of Atmospheric Pollutants

A

– Carbon monoxide replaces O2 in humans
– sukphur dioxide creates respiration problems
– acid rain from sulphur dioxide kills plants
– particulates lead to global dimming and health problems

28
Q

Sustainable development

A

– We use the earths resources for warmth, shelter, food, transport
– natural resources are supplemented by agriculture
– finite resources from, earth ,ocean, atmosphere
Does chemistry allow sustainability and needs for future generations

29
Q

Potable water

A

Water thats treated for humans to drink but not pure

30
Q

Methods to produce post for water

A

– From freshwater is passed through a mash then three sand/gravel is a filter solids
– sterilisation is used to kill harmful microbes

31
Q

Desalinisation of water

A

– Use membranes (reverse osmosis)
– the water passes through membranes that sort his tracks
– but needs a lot of energy and it cost a lot

32
Q

Distilling water required practical

A

– Test pH with pH meter
– test for sodium ions (still) with flame test and test for chlorine few drops of nitric acid plus silver nitrate to form white precipitative
– to distil pour salt water in apparatus and water evaporates and then condenses
– the test if it is pure PH should be 7

33
Q

Stages of waste water treatment

A

– Screening, removing large materials
– sedimentation in a tank, heavy objects sink
– effluent removed and treated book through aerobic digestions, the airbrakes down the matter
– the slides releases methane gas used for energy for fertilisation
– the waste water with toxic substances use UV light or membranes

34
Q

Alternative methods of extracting metals (copper is finite)

A

– Bioleaching, uses bacteria to produce leachate solutions that contain metal pole compounds
– phytomining, plants absorb metal compounds plants harvested and burnt to produce ash that contains it

35
Q

Problems with these alternative methods

A

– Extracting requires a lot of energy plus fossil feuls

36
Q

Life-cycle assessment

A

– Raw materials that can damage the local environment
– manufacturing plus packaging, energy plus pollution produce
– uses of the products (burning)
– product disposal, landfill plus energy use for transport

37
Q

Comparing life-cycle assessments

A

– Plastic bag uses crude oil, fractional distillation, it is reused, recyclable but not biodegradable
– timber, process with a lot of energy, are usually used once, biodegradable but non-toxic and recycled

38
Q

Problems with LCAs

A
  • Effects of pollutants hard to give value

– could be biased in order to support claims of companies

39
Q

Reducing the use of resources

A

– Recycling plus reuse

– glass can be crushed or melted to produce other products

40
Q

What is corrosion?

A

– Destruction of materials by chemical reactions (rusting with Air water)

41
Q

How to prevent corrosion?

A

– Painting/coating with plastic
– electroplating (electrolysis)
– oil/creases for moving parts
– galvanising (spraying with zinc)

42
Q

Alloys

A

– Most metals today
– gold measured by carrots
– high carbon steel (strong but brittle), low carbon steel (easily shaped)

43
Q

Ceramics

A

– Clay ceramics shaped by wet clay and heat in furnace

44
Q

Composites

A

– Fibreglass, low density, high strength
– carbon fibre, light, strong
– concrete buildings
– wood

45
Q

Properties of polymers (ceramics, polymers)

A

– Low density poly (ethene) moderate temp under high-pressure plus catalyst (bags)
– high density poly (E 15) at low temperature in low pressure with different catalyst more rigid

46
Q

Two types of polymers

A

– Thermo softening, individual chains with weak forces

– thermosetting, monomers from cross links and solid structure and don’t soften when heated

47
Q

Stages of the haber process (nitrogen plus hydrogen goes to ammonia)

A

– Hydrogen and nitrogen ratio 3 to 1
– put it into a reaction vessel with iron catalyst, 450°C, 200 ATM
– condenser for liquid ammonia
– unuse H/N recycled

48
Q

compromises for the haber process

A

– For a max yield plus speed
– increase pressure means more ammonia produce but it costs a lot of money and is dangerous
– iron catalyst increases speed

49
Q

NPK fertilisers

A

– Compounds of nitrogen, phosphorus, potassium to increase the growth of plants and the yield

50
Q

How to obtain Nitrogen, Potassium and Phosphorus

A
  • nitrogen from ammonia
    – Potassium obtained by mining
    – phosphate rock can not be directly used as a fertiliser in brackets treated
51
Q

Ammonia in industry

A

– giant Vats, increased concentration, exothermic

– he evaporates water to produce concentrated ammonium nitrate

52
Q

Ammonia in the lab

A
  • Small-scale titration or crystallisation
    – current lower concentration which is safer
    – ammonium nitrate crystals are formed
    – slower process than the industry

Chemistry (13 decks)

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