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GCSE Chemistry > paper 2 memorise > Flashcards

paper 2 memorise Flashcards

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1
Q

how does concentration of the reactants affect rate?

A
  • more reacting particles in the same volume of liquid
  • particles will collide more frequently
  • more successful collisions
  • if conc increases then rate increases
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2
Q

how does pressure affect rate?

A
  • more reacting particles in the smaller volume
  • particles will collide more frequently
  • more successful collisions
  • if pressure increases then rate increases
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3
Q

how does the surface area of the reactants affect rate?

A
  • if oslid id broken down inot smaller pieces or powder then surface area increases
    -more particles are exposed to reactant
  • more frequent collisions per unit time
  • more successful collisions
  • if surface area increases then rate increases
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4
Q

how does temperature affect rate?

A
  • at higher temp then particles gain more kinetic energy so they move faster
  • so they collide with more force / energy
  • more frequent collisions and more collisions with energy greater than or equal to activation energy
  • so more frequent successful collisions
  • so as temp increases, rate increases
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5
Q

how does the presence of a catalyst affect rate?

A
  • provides an alternative route for the reaction with a lower activation energy needed for a successful reaction
  • but more successful collisions even if the frequency of the collisions stays the same
  • catalyst increases rate
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6
Q

what does the collision theory say?

A

chemical reactions can occur only when reacting particles collide with each other and with sufficient energy

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7
Q

define activation energy

A

The minimum amount of energy that particles must have to react

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8
Q

what is Le Chateliers principle?

A

if a system is at equilibrium and a change is made to any of the conditions, then the system responds to correct the change.

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9
Q

what happens If the concentration of a reactant is increased?

A

more products will be formed until equilibrium is reached again

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10
Q

what happens If the concentration of a product is decreased?

A

more reactants will react until equilibrium is reached again.

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11
Q

what happens If the temperature of a system at equilibrium is increased?

A
  • amount of products increases for an endothermic reaction
  • amount of products decreases for an exothermic reaction
    EQUILIBRIUM SHIFTS IN ENDOTHERMIC REACTION
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12
Q

what happens If the temperature of a system at equilibrium is decreased?

A

EQUILIBRIUM SHIFTS TO EXOTHERMIC
- amount of product increases for exothermic reaction
- amount of products decreases for endothermic

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13
Q

what happens if the pressure increases in a system thats at equilibirum?

A

the equilibrium position to shift towards the side with the smaller number of molecules as shown by the symbol equation for that reaction
LOOK AT BIG NUMBERS ONLY

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14
Q

what happens if the pressure decreases in a system thats at equilibirum?

A

the equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction
LOOK AT BIG NUMBERS ONLY

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15
Q

define a pure substance

A

a single element or compound, not mixed with any other substance.

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16
Q

define formulation

A

a mixture that has been designed as a useful product

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17
Q

how are formulations made?

A

by mixing the components in carefully measured quantities to ensure that the product has the required properties

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18
Q

give examples of formulations?

A

fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods

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19
Q

what is the test for hydrogen?

A

a burning splint held at the open end of a test tube of the gas. Hydrogen burns rapidly with a pop sound.

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20
Q

what is the test for oxygen?

A

a glowing splint inserted into a test tube of the gas. The splint relights in oxygen.

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21
Q

what is test for carbon dioxide?

A

bubbled through limewater the limewater turns milky (cloudy).

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22
Q

what is the test for chlorine?

A

damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white.

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23
Q

what is flame for lithium?

A

crimson

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24
Q

whats the flame for calcium?

A

orange red

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25
whats the flame for sodium?
yellow
26
whats the flame for potassium?
lilac
27
whats the flame for copper?
green
28
what happens to colours during a flame test if its a compound?
some colours may be masked
29
what is the test for aluminium ions?
add sodium hydroxide solution, it forms a white precipitate and dissolves in excess sodium hydroxide.
30
what is the test for calcium ions?
add sodium hydroxide solution, it forms a white precipitate
31
what is the test for magnesium ions?
add sodium hydroxide solution, it forms a white precipitate
32
what is the test for copper(II) ions?
add sodium hydroxide solution, it forms a blue precipitate
33
what is the test for iron(II) ions?
add sodium hydroxide solution, it forms a green precipitate
34
what is the test for iron(III) ions?
add sodium hydroxide solution, it forms a brown precipitate
35
what do carbonates react with?
Carbonates react with dilute acids to form carbon dioxide gas
36
what is the test for chloride ions?
add dilute nitric acid, add silver nitrate solution, precipitate is white
37
what is the test for bromide ions?
add dilute nitric acid, add silver nitrate solution, precipitate is cream
38
what is the test for iodide ion?
add dilute nitric acid, add silver nitrate solution, precipitate is yellow
39
what is the test for sulphate ions?
add dilute hydrochloric acid, add barium chloride solution, a white precipitate forms
40
what are the advantages of instrumental methods over chemical methods?
rapid, sensitive, accurate
41
how does flame emission spectroscopy work?
The sample is put into a flame and the light given out is passed through a spectroscope. The output is a line spectrum that can be analysed to identify the metal ions in the solution and measure their concentrations.
42
what is the percentage of gases in the air today?
80% nitrogen 20% oxygen small number of other gases
43
how did the atmosphere of earth first happen?
- early atmosphere consisting of mainly carbon dioxide with little or no oxygen gas - intense volcanic activity that released nitrogen which gradually built up in the atmosphere - there may have been small proportions of methane and ammonia. - water vapour condensed to form the oceans. At the start of this period the Earth’s atmosphere consisted of mainly carbon dioxide with little or no oxygen gas. - When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere.
44
how did the atmosphere of earth develop?
- Algae and plants produced the oxygen by photosynthesis - Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve. - Algae and plants decreased the percentage of carbon dioxide in the atmosphere by photosynthesis. so CO2 decreased - Carbon dioxide was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon.
45
how is crude oil and natural gas formed?
- CO2 is taken up by algae in the ocean - when they die it falls to the seabed - they are layered in layers of sediment, mud and sand - caprock traps natural gas - compressed under extreme heat and pressures over millions of years - crude oil and gas is extracted from the seabed
46
how is coal formed?
- plants in swaps die and land in muddy surfaces - covered in layers of mud - compressed over millions of years to form coal
47
describe the greenhouse effect
- the sun emits short wavelength radiation - the earth absorbs this and heats up - the earth emits long wavelength radiation - the layer of greenhouse gas traps the radiation so it cannot go back into space - so the temperature of the earth increases
48
what are 2 human activities that release carbon dioxide into the air?
burning fossil fuels, driving petrol or diesl cars
49
what are 2 human activities that release methane into the air?
- raising livestock like cows - decay of organic waste in landfill sites
50
describe briefly four potential effects of global climate change
- extinction of species - raising sea levels due to melting of polar ice caps - migration from areas that suffer from droughts and flooding - decreasing crop yield for all major world crops
51
define carbon foootprint
the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
52
what actions can reduce the carbon dioxide emitted by humans?
use less fossil fuels, use renewable energy, save energy, using public transport, plant more trees
53
why are the actions that can be done to prevent carbon dioxide emissions limited?
its more difficult, expensive, planting trees removes land for crops
54
how is soot formed?
due to incomplete combustion because of insufficient oxygen
55
how is carbon monoxide formed?
due to incomplete combustion because of insufficient oxygen
56
how is the oxides of nitrogen formed?
due to high pressures and temperatures, nitrogen in the air binds to the oxygen in the air
57
what are the properties of carbon monoxide gas?
a toxic gas. It is colourless and odourless and so is not easily detected.
58
what does sulphur dioxide and oxides of nitrogen cause?
respiratory problems in humans and cause acid rain.
59
what do particulates cause?
global dimming and health problems for humans
60
define potable water
Water that is safe to drink, but the water is not pure water in the chemical sense because it contains dissolved substances.
61
how is potable water produced?
- choosing an appropriate source of fresh water - passing the water through filter beds; to remove different sized insoluble solids - sterilising, sterilising agents used for potable water include chlorine, ozone or ultraviolet light; done to kill microbes
62
how is desalination done?
by distillation or by processes that use membranes such as reverse osmosis
63
what is the method to treat sewage?
- sewage is screened by passing it through a mesh, this removes solids and pieces of grit - sewage is settled in a large sedimentation tank which produces liquid effluent and a semi-solid sludge which sinks - the sludge is removed and digested by anaerobic bacteria. these produce biogas which can be used for electricity - the digested sludge can be used as a fertiliser for farming - the liquid effluent contains large amounts of organic molecules and harmful microorganisms. these need to be reduced before the water return to the environment. - air is bubbled through the liquid effluent which allows the aerobic bacteria to multiply - this bacteria digests harmful microorganisms and organic molecules - after this the liquid effluent can be discharged to nearby seas
64
what is the easiest way to produce potable water?
use ground water from aquifers which is safe to drink once its treated with chlroine
65
what are the cons of desalination?
uses a lot of energy and is expensive
66

GCSE Chemistry (17 decks)

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