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Chemistry > Chemistry 4 - Analysis and the Earth's resources (C12 - C15 Not chronological) > Flashcards

Chemistry 4 - Analysis and the Earth's resources (C12 - C15 Not chronological) Flashcards

1
Q

What formed the Earth’s early atmosphere?

A

Volcanic activity

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2
Q

What was the most abundant gas in the earth’s early atmosphere?

A

Carbon Dioxide.

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3
Q

What changed the amount of Carbon dioxide and increased the amount of Oxygen?

A

The evolution of green, photosynthetic plants.

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4
Q

What are the stages of Sewage Treatment?

A
  • Passed through pumping station
  • Screened
  • Primary sedimentation
  • Biological treatment
  • Secondary sedimentation
  • Water is disinfected/sterilised at this point
  • Added to river
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5
Q

What is the Anode?

A

The positive electrode

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6
Q

What is the Cathode?

A

The negative electrode

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7
Q

What is the difference between a pure and impure substance?

A

A pure substance can be a compound, but it must contain only one substance. An impure substance is a mixture of two or more different elements or compounds.

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8
Q

What can be used to identify pure substances?

A

The fact that they each have a specific boiling and melting point.

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9
Q

What can melting and boiling point data be used for in pure substances?

A

Identifying and distinguishing them.

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10
Q

What are formulations?

A

Useful mixtures made up in different proportions.

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11
Q

What can scientist use to analyse unknown substances in solution?

A

Paper chromatography.

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12
Q

What is an Rf value?

A

A retention factor, it can be measured and matched against databases to identify specific substances.

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13
Q

What is the equation for an Rf value?

A

Rf = distance moved by substance / distance moved by solvent.

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14
Q

What does hydrogen gas do when you apply a lighted splint?

A

Burns rapidly with a pop.

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15
Q

What does oxygen do to a glowing splint?

A

Relights it.

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16
Q

What does Carbon dioxide gas do to limewater?

A

Turns it milky

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17
Q

What does chlorine gas do to damp blue litmus paper?

A

Turns it white.

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18
Q

Name two ways that some positive ions (Cation) can be identified.

A
  • Some metal ions (including Group 1 and 2 cations) can be identified in their compounds using FLAME TESTS.
  • SODIUM HYDROXIDE solution can be used to identify metal ions that form insoluble hydroxides in precipitation reactions.
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19
Q

How can you identify carbonates?

A

By adding dilute ACID, which produces CARBON DIOXIDE GAS. The gas turns limewater milky.

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20
Q

What is a carbonate?

A

A compound containing carbonate ions (-2 charge)

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21
Q

What is a halide ion?

A

A halogen atom bearing a negative charge.

22
Q

How is the presence of halides identified?

A

Adding NITRIC ACID to the solution, then SILVER NITRATE SOLUTION. This produces a precipitate of silver halide.

23
Q

When a halide is identified resulting in the production of a silver nitrate precipitate, what colour will this precipitate be in the presence of chloride, bromide or iodide ions respectively?

A

If chloride ions are present (Cl-) - White
If bromide ions are present (Br-) - Cream
If iodide ions are present (I-) - Yellow

24
Q

Name an instrumental method of analysing chemical substances.

A

Flame emission spectroscopy

25
Q

What does flame emission spectroscopy identify?

A

Which metal ions are present from their characteristic line spectra, and also the concentration of the metal ions in a solution.

26
Q

Name 3 renewable sources of energy.

A

Biofuels, wind energy, hydroelectricity

27
Q

Name 3 non-renewable sources of energy.

A

Crude oil, uranium and natural gas

28
Q

What is potable water?

A

Water that is safe to drink

29
Q

Name 3 ways that water can be made fit to drink specifically by sterilising it.

A
  • Adding chlorine
  • Adding ozone
  • Passing UV light through
30
Q

Why is water rarely purified by distillation?

A

Expense due to energy requirement.

31
Q

Name and explain a desalination method that does not include sterilisation or distillation.

A

Reverse osmosis uses membranes to separate dissolved salts from salty water.

32
Q

How is copper extracted from ore most commonly?

A

Smelting.

33
Q

How can copper be extracted from solutions of copper compounds?

A

Electrolysis.

34
Q

What is a Life Cycle Assessment? (LCA)

A

An assessment carried out to identify environmental impact of products, processes or services.

35
Q

How can the 4 stages of an LCA be summarised?

A

Raw material extraction - > Manufacture - > Use/Reuse/Maintenance - > Recycle/Waste management

36
Q

What two things are needed to cause iron to oxidise (Rust)

A

Oxygen and Water

37
Q

What can prevent iron from rusting?

A

Creating a barrier between the air/water and the iron.

38
Q

What is sacrificial protection?

A

When rusting is prevented by attaching the iron to a more reactive metal.

39
Q

What are alloys?

A

Combinations of metals that are harder than pure metals.

40
Q

Why are alloys harder than pure metals?

A

Because the regular layers in a pure metal are distorted by differently sized atoms in an alloy.

41
Q

What are polymers?

A

A substance made up of very large molecules made up of many repeating units.

42
Q

What are monomers?

A

Small reactive molecules that react together to form large molecules.

43
Q

What affects the properties of a polymer? Two things.

A
  • The monomers that produces the polymer.

- Changing reaction conditions

44
Q

What are thermosoftening polymers?

A

Polymers that will soften or melt easily when heated because their intermolecular forces are relatively weak.

45
Q

What are thermosetting polymers?

A

Polymers that do not melt when heated because their covalent bonds are strong forming cross links between polymer chains.

46
Q

What is soda glass made of?

A

Sand, limestone, and sodium carbonate

47
Q

What is borosilicate glass made of?

A

Sand and boron trioxide

48
Q

What are the conditions under which the Haber process is most frequently executed and why?

A

450 degrees celsius and 200 atmospheres using an iron catalyst. These are the most efficient conditions economically for the process.

49
Q

Why are higher pressures not used in the Haber process?

A

Because despite the higher ammonia yield, it is too expensive.

50
Q

Why are lower temperatures not used in the haber process despite yielding more ammonia?

A

Because this would make the process less efficient due to the slower speed.

Chemistry (19 decks)

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