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a level chemistry > group 2 and group 7 > Flashcards

group 2 and group 7 Flashcards

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1
Q

What is the trend in reactivity in group 2 and why

A

reactivity increases down the group as ionisation energies decrease due to increasing shielding and atomic radius increases so easier to lose electrons

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2
Q

The test for reactivity of group 2 metals and results

A

add to dilute hydrochloric acid and observe vigorous reactions and effervesance and the metals further down the group will be more reactive

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3
Q

What is the trend of the melting point down group 2

A

melting point decreases down the group as the atomic radius increases an the electrostatic forces of attraction are weaker

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4
Q

What is the trend in density of group 2 metals down the group

A

the density increases down the group as the atomic radius is so big

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5
Q

What is the trend in solubility of group 2 hydroxides down the group

A

the solubility of group 2 hydroxides increases down the group

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6
Q

If the solubility in a group 2 metal is high what does that mean in terms of OH ions

A

more will be present in the soltuion and therfeore the solution will be more alkaline

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7
Q

what is the equation of group 2 hydroxide ions dissolving

A

X(OH)2 —-> X+2 + 2OH-

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8
Q

What is the trend in the solubility of group 2 sulfates

A

the solubility of group 2 sulfates decreased down the group

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9
Q

what is the general equation of group 2 metals reacting with oxygen

A

2M +O2 —> 2MO

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10
Q

What group 2 metals also form peroxides when reacting with oxygen

A

barium and strontium from BaO2 and SrO2

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11
Q

what is the general equation for metals reacting with water

A

M + 2H2O –> M(OH)2 +H2

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12
Q

what group 2 metal doesnt react with water

A

beryllium

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13
Q

what group 2 metal reacts slowly with water and what other way can it react with water and what does it produce

A

magnesium reacts extremely slowly with liquid water but it can react vigourously with stream to make magnesium oxide and gas

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14
Q

what do group 2 metals make result wise when reacted with dilute HCL

A

colourless solutions of metal salts and hydrogen gas

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15
Q

what is the general equation when a group 2 metal racts with dilute HCL

A

M + 2HCL –> MCl2 + H2

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16
Q

what do group 2 metals form when they react with sulfuric acid 2 types of

A

insoluble sulphate is formed with strontium and barium and the rest of group 2 is a soluble sulphate

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17
Q

what is the general equation for the reaction of metals with dilute H2SO4

A

M + H2SO4 –> MSO4 + H2

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18
Q

what happens when you react barium and strontium with sulfuric acid in terms of the solid oxide

A

they form an insoluble sulphate at the surface which stops the solid oxide beneath reacting with the acid

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19
Q

what 3 products do group 2 carbonates form when reacted with hydrochloric acid

A

they form a soluble chloride salt, water and carbon dioxide

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20
Q

what group 2 carbonates form insoluble sulphate layers and what does it cause

A

calcium, barium and strontium from an insoluble sulphate layer on their solid carbonates which means the solid carbonate cant react with the acid and the reaction stops

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21
Q

what is seen when you add a carbonate to a dilute acid

A

bubbling of CO2 is produced

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22
Q

what is the use of calcium hydroxide

A

neutralise the pH of fields

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23
Q

what can calcium carbonate be used for

A

neutralising fields and removing sulfur dioxide from flue gases

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24
Q

what is barium sulphate used for

A

it is used as a barium meal for pateints getting xrays on their intestines as it highlights them by absorbing the xrays

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25
Q

why is barium sulphate safe to use in xrays

A

it is insoluble and won’t get absorbed into blood

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26
Q

what is the use of magnesium hydroxide and how does it work

A

it is used to treat indigestion as it is slightly soluble so will from a slight alklaine solution which neutralises the HCL in the stomach

27
Q

what is the use of magnesium and what is the equation

A

magnesium is used in the extraction of titanium from its ore
TiCL4 + Mg –> Ti + 2MgCl2

28
Q

what is the trend in group 7 boiling points down the group

A

boiling point increases as the van der waals in diatomic molecules get stronger as the elements get bigger due to increasing atomic radius

29
Q

what is the trend in group 7 volatility going down the group and why

A

the volatility decreases as boiling points increase due to van der waals getting stronger

30
Q

what is the trend in oxidising power going down group 7 and why

A

it decreases as they become less electronegative due to an increase in atomic radius meaning the joining electron will experience more shielding and less attraction to the nucleus

31
Q

what is the trend in reducing power of halides down the group

A

the reducing power increase down the group due to how easiliy electrons are lost because of shielding ang a large atomic radius resulting is less attraction between nucleus and electronsso they are held less tightly

32
Q

what is the test for halide ions

A
  1. dissolving the solution in nitric acid to remove carbonate ions
  2. add silver nitrate drop by drop and a precipitate will form
  3. then add dilute ammonia to dissolve chlroide
  4. then add concentrated ammonia to dissolve bromide
33
Q

what are the results for positive halide ion test

A

chloride- white
bromide- cream
iodide- yellow

34
Q

what are the equations for the reaction between concentrated sulfuric acid and fluorine

A

H2SO4 + NaF –> NaHSO4 + HF

35
Q

what are the equations for the reaction between concentrated sulfuric acid and chlorine and what are the state symbols

A

H2SO4 + NaCl –> NaHSO4 + HCl
H2SO4 is liquid
NaCl is solid
NaHSO4 is a solid
HCl is a white gas

36
Q

what are the equations for the reaction between concentrated sulfuric acid and bromine

A

H2SO4(l)+ NaBr(s) –> NaHSO4(s)+ HBr(g)
H2SO4(l) + HBr(g) –> Br2(g) + SO2(g) + H2O(l)

37
Q

what are the equations for the reaction between concentrated sulfuric acid and iodine

A

H2SO4 (l)+ NaI(s) –> NaHSO4(s) + HI (g)
H2SO4 (l)+ 2HI(g) –> I2(g) + SO2(g) + 2H2O(l)
H2SO4(l) + 6HI(g) –> 3I2(g)+ S(s) + 4H2O(l)
H2SO4(l) + 8HI(g) –> 4I2(g) + H2S(g) + 4H2O(l)

38
Q

what are the results of the reaction between concentrated sulfuric acid and chloride

A

white fumes of HCl gas

39
Q

what are the results of the reaction between concentrated sulfuric acid and bromide

A

white misty fumes of HBr and reddish brown gas of Br2

40
Q

what are the results of the reaction between concentrated sulfuric acid and iodine

A

violet/ purple vapour of I2
yellow solid of sulfur
strong bad smell of H2S

41
Q

what is a dispropotionation reaction

A

a reaction where the same species is oxidised and reduced

42
Q

how is bleach made

A

2NaOH(aq) + Cl2 (g) –> NaCl (aq) + NaClO (aq)+ H2O (l)

43
Q

what is the use of chlorine

A

chlorine is used to clean water and make it drinkable and to keep swimming pools clean

44
Q

what compound is made in the reaction of chlorine and sodium hydroxide that cleans that water

A

NaClO
NaCLO is bleach
ClO- is chlorate (i)

45
Q

even though there are toxic effects of using chlorine to kill bacteria why do we do it

A

the benefits of clean water by chlorine killing bacteria outweighs its risk of toxic effects

46
Q

why is keeping shallow pools more difficult/expensive

A

shallow pools lose chlorine rapidly from the water due to evaporation so it costs more

47
Q

put chlorine, iodine and bromine in order of reactiveness and what ones would displace what

A

chlorine
bromine
iodine

48
Q

what solutions forms when iodine is displaced by chlorine and bromine

A

a brown solution of iodine (I2)

49
Q

what colour solution forms when bromine is displaced by chlorine and what are the products of the reaction

A

a orange solution of bromine (Br2)

KCl + Br2

50
Q

what can you do to test for compounds of some group 2 metals using a bunsen

A

flame spec
1. dip a nichrome wire loop in concentrated hydrochloric acid to clean it
2. then dip it into compound
3. hold the loop in the clear blue part of a bunsen burner flame

51
Q

results for group 2 metal ions in flame spec

A

calcium- brick red
strontium- red
barium- pale green

52
Q

how can you use dilute sodium hydroxide to identify group 2 ions and what are the results

A
  1. add dilute sodium hydroxide solution in excess
  2. dropwise to a test tube containing the metal ion and observe precipitate

magnesium white precipitate when NaOH is in excess ( before excess is slightly white)

calcium slightly white precipitate
strontium slightly white precipitate

barium is no change

53
Q

what are the results of adding sodium hydroxide to group 2 ions

A

Mg- white precipitate
Ca- slight white precipitate
Sr- slight white precipitate
Ba- no change

54
Q

what is the test for ammonium ions and what is the equation for the reaction

A
  1. add dilute sodium hydroxide
  2. gently heat the mixture
  3. then add damp red litmus paper and it should go blue

NH4+ + OH-&raquo_space; NH3 + H2O

55
Q

what is the test for sulfate ions and whats a positive result

A
  1. add dilute hydrochloric acid
  2. add barium chloride solution

a white precipitate is a positive test

56
Q

what is the test for hydroxide ions

A

dip a damp piece of red litmus paper into the solution and hydroxide ions turn the litmus paper blue

57
Q

test for carbonate ions

A
  1. add dilute hydrochloric acid
  2. carbon dioxide is released
  3. CO2 turns limewater cloudy so bubble the gas through the test tube of limewater to get a result
58
Q

why is using chlorine in outdoor pools risky for the environment

A

it is risky because they can produce chlorinated hydrocarbons

59
Q

what is the equation when chlorine reacts with water

A

Cl2(g) + H2O (l) <–> ClO- (aq) + 2H+ (aq) + Cl- (aq)

60
Q

what can chlorine do in the presence of sunlight and what is the equation

A

decompose
Cl2 (g)+ H20 (l) <–> 2Cl- (aq) + 2H+ (aq) + 1/2 O2(g)

61
Q

if you react NaF with with silver nitrate what do you get

A

a colourless solution

62
Q

what are the equations for the removal of sulfur from flue gases

A

CaO(s) + 2H2O (l) + SO2(g) –> CaSO3(s) + 2H2O(l)
CaCO3(s) + 2H2O(l) + SO2 (g) –> CaSO3 (s) + 2H2O (l) + CO2(g)

63
Q

what is the trend in electronegativity down group 7

A

electronegativity decreases down the group as larger atoms attract eletrons less due to the outer electrons being further from the nucleus and more shielded as they have more inner electrons so the tendency to attract an atom lowers

a level chemistry (14 decks)

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