10 group 7 Flashcards

1
Q

what are group 7 elements called?

A

halogens

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2
Q

describe what fluorine looks like

A

pale yellow gas

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3
Q

describe what chlorine looks like

A

pale green gas

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4
Q

describe what bromine looks like

A

orange/brown liquid

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5
Q

describe what iodine looks like

A

grey solid

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6
Q

what happens to boiling point down group 7? why?

A

increases due to increased van de waals forces

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7
Q

what is the trend in electronegativity down group 7? why?

A

decreases due to atomic radius increasing and more shielding

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8
Q

what is the trend in reactivity down group 7?

A

decreases

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9
Q

do halogens get more or less oxidising when going down group 7?

A

less oxidising

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10
Q

what is the rule for halide displacement reactions?

A

if the halide is lower than the halogen in the periodic table, halogen will displace

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11
Q

what does KBr react with? write an equation and the observation

A

Cl2
Cl2 + 2Br- -> 2Cl- + Br2
orange solution made

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12
Q

what does KI react with?

A

Cl2 and Br2

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13
Q

write the equation and state the observation of the reaction of KBr with Cl2

A

Cl2 + 2Br- -> 2Cl- + Br2
orange solution made

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14
Q

write the equation and state the observation of the reaction of KI with Br2

A

Br2 + 2I- -> 2Br- + I2
brown solution

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15
Q

what is the chemical name for bleach?

A

sodium chlorate
NaClO

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16
Q

write the equation for bleach

A

2NaOH + Cl2 -> NaClO + NaCl + 2H2O

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17
Q

what type of reaction is the one for bleach?

A

disproportionation reaction

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18
Q

what is a disproportionation reaction?

A

a reaction where an element is both oxidised and reduced

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19
Q

what is reduced and oxidised in the reaction for bleach?

A

Na

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20
Q

how can you kill bacteria in water?

A

by adding chlorine gas

21
Q

what is the equation for the reaction between water and chlorine?

A

H2O + Cl2 -> 2H+ + Cl- + ClO-

22
Q

what kind of reaction is the reaction used to kill bacteria in water?

A

disproportionation reaction

23
Q

what is both reduced and oxidised in the reaction for killing bacteria in water?

A

Cl

24
Q

what are the disadvantages for putting chlorine in drinking water?

A
  1. toxic (irritates respiratory system)
  2. liquid chlorine causes chemical burns
25
Q

what are the advantages for putting chlorine in drinking water?

A
  1. destroys microorganisms that cause disease
  2. long lasting so reduces bacteria build up
  3. reduces growth of algae
26
Q

which, out of I- and F-, is a more powerful reducing agent? why?

A

I- more powerful because it is at the bottom of group 7 and has a larger atomic radius so the outer electron can be lost more easily

27
Q

what are two tests that can be used to prove the trend in reducing agents down group 7?

A
  1. reaction with sulfuric acid
  2. reaction with silver nitrate
28
Q

write the equations for how sodium Cl, Br, I and F all react with sulfuric acid

A
  1. H2SO4 + NaCl -> NaHSO4 + HCl
  2. H2SO4 + NaBr -> NaHSO4 + HBr
  3. H2SO4 + NaI -> NaHSO4 + HI
  4. H2SO4 + NaF -> NaHSO4 + HF
29
Q

what reacts with H2SO4 to make SO2?

A

Br and I

30
Q

what reacts with H2SO4 to make S?

A

I

31
Q

hat reacts with H2SO4 to make H2S?

A

I

32
Q

write the equation for the reaction between H2SO4 and Br to make SO2 and state the observation

A

H2SO4 + 2H+ + 2Br- -> Br2 + SO2 + 2H2O
brown fumes of Br2

33
Q

write the equation for the reaction between H2SO4 and I to make SO2 and state the observation

A

H2SO4 + 2H+ + 2I- -> I2 + SO2 + 2H2O
acidic gas and black solid iodine

34
Q

write the equation for the reaction between H2SO4 and I to make S and state the observation

A

H2SO4 +6H+ + 6I- -> 3I2 + S + 4H2O
yellow solid of sulfur

35
Q

write the equation for the reaction between H2SO4 and I to make H2S and state the observation

A

H2SO4 + 8H+ + 8I- -> 4I2 + H2S + 4H2O
rotten egg smell and black solid iodine

36
Q

write the equation for silver ions reaction with F-
give state symbols and state observation

A

Ag+ (aq) + F- (aq) -> AgF (aq)
colourless solution

37
Q

write the equation for silver ions reaction with Cl-
give state symbols and state observation

A

Ag+ (aq) + Cl- (aq) -> AgCl (s)
white precipitate

38
Q

write the equation for silver ions reaction with Br-
give state symbols and state observation

A

Ag + (aq) + Br- (aq) -> AgBr (s)
cream precipitate

39
Q

write the equation for silver ions reaction with I-
give state symbols and state observation

A

Ag + (aq) + I- (aq) -> AgI (s)
yellow precipitate

40
Q

what does Br2 look like?

A

brown fumes

41
Q

what does S look like?

A

yellow solid

42
Q

what is the observation for H2S?

A

rotten egg smell

43
Q

what do AgF, AgCl, AgBr and AgI look like?

A

AgF = colourless solution
AgCl = white precipitate
AgBr = cream precipitate
AgI = yellow precipitate

44
Q

what is the formula for sulfates and how do you test for them? what observation is a positive result?

A

SO4 2-
add HCl then BaCl2
white ppt

45
Q

what is the formula for hydroxides and how do you test for them? what observation is a positive result?

A

OH-
red litmus/universal indicator
litmus: blue
indicator: blue/purple

46
Q

what is the formula for carbonates and how do you test for them? what observation is a positive result?

A

CO3 2-
add HCl
effervesence with CO2
(limewater turns cloudy)

47
Q

what is the formula for ammonium and how do you test for them? what observation gives a positive result?

A

NH4+
add NaOH and put damp red litmus over
ammonia gas will turn litmus blue

48
Q

how do you test for group 2 ions and what are the observations for Ca2+, Sr2+ and Ba2+?

A

flame tests
Ca2+ = brick red
Sr2+ = red
Ba2+ = pale green