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N5 Chemistry > Unit 3 > Flashcards

Unit 3 Flashcards

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1
Q

why do metals conduct electricity?

A

because the outer electrons are delocalised (free to move)

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2
Q

what is a metallic bond?

A

the electrostatic force of attraction between positively charges ions and their delocalised electrons

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3
Q

complete the equation

metal + oxygen =

A

metal oxide

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4
Q

complete the equation

metal + water =

A

metal hydroxide + hydrogen

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5
Q

complete the equation

metal + acid =

A

salt + hydrogen

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6
Q

how can metals be used to make soluble salts?

A

excess metal is added to the correct acid
mixture is filtered to remove unreacted metal
filtrate is evaporated to dryness

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7
Q

what is reduction?

A

gain of electrons

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8
Q

what is oxidation?

A

loss of electrons

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9
Q

what is a redox reaction?

A

when both oxidation and reduction take place at the same time

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10
Q

when a metal is extracted from its ore is a metal being oxidised or reduced?

A

reduced

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11
Q

what is an ore?

A

a compound containing useful amounts of metal ions

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12
Q

what happens to a metal ion when they are being extracted from metal ores?

A

they gain electrons to change from ions to atoms

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13
Q

how are very reactive metals obtained from their ores?

A

electrolysis

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14
Q

how can very unreactive metals be obtained from their ores?

A

by heat alone

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15
Q

how are most metals extracted from their ores?

A

heating with carbon or carbon monoxide

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16
Q

what is electrolysis?

A

the breaking of an ion compound into its elements using electricity

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17
Q

why must a D.C. supply be used for electrolysis?

A

to allow the elements to build up at the electrodes for identification

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18
Q

what happens at the electrodes during electrolysis?

A

positive ions gain electrons at the negative electrode

negative ions lose electrons at the positive electrodes

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19
Q

how do you make a current flow using two different metals in a solution of their own ions? (2 half cells)

A

connect the metals with a wire
connect the solutions with a salt bridge
the electrons will flow along the wire

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20
Q

why does graphite make a good electrode?

A

it is unreactive but conducts electricity

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21
Q

with a non-metal half-call how do you work out which way the electrons are going to move?

A

the oxidation reaction always gives electrons to the reduction reaction

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22
Q

what does a salt bridge (ion bridge) do?

A

it links two half cells and completes the circuit by allowing ions to pass across the bridge

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23
Q

what is an electrolyte?

A

a solution containing ions which can conduct electricity?

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24
Q

how can the most simple cell be made?

A

put 2 different metals in an electrolyte

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25
Q

what is a half-cell?

A

a metal in a solution of its own ions

26
Q

do all half-cells contain a metal?

A

no- graphite may be used

27
Q

which way do electrons travel in an electrochemical cell?

A

from the metal higher up in the electrochemical series to the one lower down

28
Q

how does the voltage in electrochemical calls vary?

A

the further apart the metals are in the electrochemical series, the greater the voltage will be

29
Q

give an example of a polymer?

A

plastics, starch, rubber, etc.

30
Q

what are polymers?

A

long chain molecules made up by joining together lots of smaller molecules called monomers

31
Q

what is a monomer?

A

a small molecule with a functional group such as C=C that will allow it to become part pf a long chain

32
Q

what are addition polymers?

A

polymers made by joining unsaturated molecules together in an addition reaction

33
Q

how are addition polymers named?

A

use the prefix ‘poly’ in front of the monomer name

e.g. propane = polypropane

34
Q

what is the process of making polymers called?

A

polymerisation

35
Q

what are repeating groups?

A

a small section of polymer that is repeated over and over to make the complete chain/

36
Q

which elements do the compounds in fertilisation?

A

Nitrogen, potassium and phosphorous (NPK)

37
Q

what do fertilisers do?

A

put elements essential for plant growth back into the soil

38
Q

which compounds are commonly used to make nitrogen salts that are used as fertiliser?

A

ammonia and nitric acid

39
Q

what is ammonia?

A

a strong smelling, colourless, soluble gas

it dissolves to make an alkaline solution

40
Q

complete the equation

ammonia solution + acid =

A

ammonium salt + water

41
Q

what process is used to make ammonia?

A

haber process

42
Q

describe the haber process

A

nitrogen and hydrogen are reacted to make ammonia using an iron catalyst and a moderate heat

43
Q

why is a moderate temperature used in the haber process?

A

at low temperatures the reaction is too slow. increasing the temperature increases the rate of reaction but also makes the backward reaction more dominant
so they compromise and go between the 2 extremes

44
Q

what process is used to make nitic acid?

A

the Ostwald process

45
Q

describe the Ostwald process

A

ammonia is reacted with oxygen and water to produce nitric acid.a platinum catalyst is used

46
Q

what is a radioisotope?

A

an isotope with an unstable nuclei which will change to become more stable by giving out radiation

47
Q

what is radioactivity?

A

particles and rays given out by unstable isotopes

48
Q

what are three types of radiation?

A
  • alpha
  • beta
  • gamma
49
Q

what is alpha radiation? (mass, charge and ability to penetrate)

A

a positively charged helium ion.

(mass=4, charge=+2 and is stopped by a sheet of paper

50
Q

what is beta radiation? (mass, charge and ability to penetrate)

A

a high energy electron

mass=0 (almost), charge=-1 and is stopped by 2mm of aluminium

51
Q

what is gamma radiation? (mass, charge and ability to penetrate)

A

it is not a particle, it is an electromagnetic ray

mass=no mass, charge=no charge and is stopped by thick lead or concrete

52
Q

what is it meant by the term half-life?

A

the time it takes for a half of the nuclei of a radioisotope to decay

53
Q

how does carbon dating work?

A

carbon-14 is an unstable radioisotope but gets into living things as carbon dioxide. as soon as somethings dies the amount carbon-14 decreases. the amount of radioactivity therefore gives its age

54
Q

how can you spend up the half life of a nuclear reaction?

A

you can’t

they are not chemical reactions so are unaffected by chemical or physical conditions

55
Q

what can radioisotopes be used for?

A

to detect and treat cancer

to detect leaks in pipes

56
Q

what can gamma rays be used for?

A
  • to sterilise surgical instruments

- to kill bacteria on food so it keeps longer

57
Q

what technique can be used to detect metals present in compounds?

A

flame testing

58
Q

what are standard solutions?

A

solutions of very accurately known concentrations

59
Q

what is a precipitate?

A

a solid formed from 2 solutions

60
Q

what are concordant titration results?

A

results that are within 0.2cm^3 of each other

N5 Chemistry (3 decks)

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