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chem > chem 13.4 > Flashcards

chem 13.4 Flashcards

(50 cards)

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1
Q

major source of metals?

A

earth’s crust

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2
Q

what does the abundance of a metal in the earth’s crust affect

A

supply of the metal

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3
Q

what are ores

A

rocks containing minerals that are high enough in concentration for extraction in the earth’s crust

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4
Q

where are most metals found

A

in metal ores

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5
Q

what form are most metals found in (and what are the exceptions)

A

most are found in the form of compounds in metal ores (w the exception of a few metals eg. gold / silver / platinum

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6
Q

what is carbon reduction

A

carbon reduction: carbon takes away the oxygen from the metal oxide (forming metal and carbon dioxide)

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7
Q

procedure of carbon extraction exp

A

heat equal amounts of x with charcoal in a crucible with a lid, leaving a small gap. x metal can be obtained as a (adj) solid inside the crucible

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8
Q

why is the lid of the crucible half open

A

to prevent the spillage of the fine carbon powder under strong heating while allowing the CO2 to escape / to prevent the copper from reacting with the oxygen in air again to form copper oxide

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9
Q

what will happen if the lid / crucible is not cooled properly before transferring to the heatproof mat and why

A

if lid is not cooled properly before transferring to the heatproof mat -> large temp difference will cause the cracking of the ceramic material

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10
Q

metal oxide + carbon

A

(w the help of heat)
metal + carbon dioxide

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11
Q

metal + oxygen

A

(w the help of heat)
metal oxide

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12
Q

metal + cold water

A

metal hydroxide + hydrogen gas

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13
Q

metal + steam (water)

A

metal oxide + hydrogen gas

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14
Q

metal + dilute acid

A

metal salt + hydrogen gas

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15
Q

what is the opposite of reduction (loss of oxygen)

A

oxidation (gain of oxygen)

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16
Q

what is exothermic and endothermic

A

exothermic (release heat)
endothermic (absorb heat)

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17
Q

metal reactivity table in order (from most to least

A

potassium
sodium
calcium
magnesium
aluminium
zinc
iron
lead
copper
mercury
silver
platinum
gold

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18
Q

which metals / ores are extracted through electrolysis of molten ores

A

potassium (potassium salt, KCl)
sodium (common salt, NaCl)
calcium (limestone, CaCo3)
magnesium (magnesite, MgCo3)
aluminium (Al2O3)

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19
Q

which metals / ores are extracted through heating in air, and then heating in charcoal

A

zinc (zinc blende, ZnS)
lead (galena, PbS)

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20
Q

which metals / ores are extracted through heating with charcoal

A

iron (haematite, Fe2O3)
copper (copper oxide, CuO)

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21
Q

which metals / ores are extracted through heating in air

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A

copper (copper pyrite, CuFeS2)
mercury (cinnabar, HgS)

22
Q

which metal / ore can be extracted through both heating or mechanical separation

Study These Flashcards
A

silver (silver glance, Ag2S) // free in nature

23
Q

which metal / ores are extracted through mechanical separation

Study These Flashcards
A

platinum (free in nature)
gold (free in nature)

24
Q

method of mechanical separation

25
the more reactive the metal…
the more stable its compound
26
what can the metal reactivity table also be used for
ease of extraction year of discovery reactivity of metal
27
which metals react w cold water
potassium sodium calcium
28
which metals react with steam
potassium sodium calcium magnesium aluminium zinc iron
29
which metals react with dilute acid
potassium sodium calcium agnesium aluminium zinc iron lead
30
which metals react with oxygen in air
potassium sodium calcium magnesium aluminium zinc iron lead copper mercury
31
extraction of aluminium from molten aluminium oxide: which element is attracted to which electrode + observation
Al3+ is attracted to the -ve electrode and forms Al there (observation: a silvery solid is formed at the -ve electrode) O2- is attracted to the +ve electrode and forms O2 there (observation: colourless gas bubbles are formed at the +ve electrode)
32
extraction of aluminium from molten aluminium oxide: overall chemical reaction
aluminium oxide -electricity-> aluminium + oxygen 2Al2O3 -electricity-> 4Al (s) + 3O2 (g)
33
extraction of aluminium from molten aluminium oxide: why is a carbon electrodes used
cheaper than metal electrodes, even if it needs to be replaced (as it dissolves into CO2 over time)
34
extraction of aluminium from molten aluminium oxide: how is the melting point of aluminium lowered and why does it need to be lowered
lowered by dissolving in cryolite as Al2O3 originally has a high melting point (>2kC), it is expensive to be heated to that temperature. by dissolving it in cryolite, its melting pt can be lowered to around 950C, allowing electrolysis to happen at a lower temp
35
extraction of aluminium from molten aluminium oxide: chemical reaction at the positive electrode
O2- —> O2 + 2e-
36
extraction of aluminium from molten aluminium oxide: chemical reaction at negative electrode
Al3+ + 3e- —> Al
37
extraction of aluminium from molten aluminium oxide: why does aluminium oxide need to be melted to extract aluminium from it
bc ores must be molten for it to conduct electricity
38
extraction of aluminium from molten aluminium oxide: how to test for Al
add HCl to the metal and test the gas formed w a burning splint (should burn with a ‘pop’ sound) only applies for metals more reactive than copper
39
extraction of aluminium from molten aluminium oxide: how to text for Al2O3
add HCl: Al2O3 should dissolve without the formation of gas
40
extraction of aluminium from molten aluminium oxide: how to test for O2
glowing splint test (should relight)
41
extraction of aluminium from molten aluminium oxide: how to test for H2
burning splint test (burns with a ‘pop’ sound)
42
extraction of aluminium from molten aluminium oxide: how to test for H2O
dry cobalt chloride paper (colour change from blue to pink)
43
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their electrical conductivity from highest to lowest
gold, copper, aluminium, iron, lead
44
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their thermal conductivity from highest to lowest:
gold, copper, iron, alumnium, lead
45
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their strength from highest to lowest:
iron, copper, aluminium, gold, lead
46
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their density from highest to lowest: (w/ rough values) also what does density affect
gold (19.30 g/cm3) lead (11.34 g/cm3) copper (8.93 g/cm3) iron (7.78 g/cm3) aluminium (2.70 g/cm3) density affects the ease of transport of the metals
47
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their melting points from highest to lowest: (w/ specific values)
iron 1540C copper 1084C gold 1064C aluminium 660C lead 327C
48
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their toxicity from highest to lowest:
lead copper (slightly) gold, aluminium and iron are non-toxic
49
from the 5 following metals: gold, iron, copper, aluminium, lead; rank their price from highest to lowest:
gold copper aluminium iron / lead (both quite cheap)
50
what should be taken into consideration when choosing metals to use
we must consider both the properties and prices when choosing the most suitable metal for a certain use (eg. although gold has a better electrical conductivity, we use copper to make electrical wires bc it is less expensive)

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