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chemistry > Group 7 > Flashcards

Group 7 Flashcards

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1
Q

What is the trend in electronegativity down group 7?

A

DECREASES
bc the number of principle energy levels (shells) increases
weaker attraction to nucleus and electrons in a covalent bond

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2
Q

What is the trend in boiling point down group 7?

A

INCREASES
size of atom increases
there are more VDW forces between molecules that need to be broken

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3
Q

What do Halogens look like at room temperature?

A

F2 - pale yellow gas
Cl2 - pale green gad
Br2 - Dark red/orange liquid
I2 - dark purple/black solid

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4
Q

What happens to a halogen’s ability to act as an oxidising agent down a group?

A

DECREASES
- atomic radius increases
- more shielding
- weaker attraction to nucleus and outer electrons so halogen gains electron less easily

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5
Q

What is the observation when chlorine oxides Br- and I-

A

Br- = yellow solution is formed
I- = brown solution formed

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6
Q

What is the observation when Br oxidises I-?

A

brown solution formed

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7
Q

What is the ionic equation for the oxidation of Br- by Cl2

A

Cl2 + 2Br- > Br2 + 2Cl-

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8
Q

What is the ionic ewuation for the oxidation of I- by Cl2?

A

Cl2 + 2I- > I2 + 2Cl-

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9
Q

What is the ionic equation for the oxidation of I- by Br2

A

Br2 + 2I- > I2 + 2Br-

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10
Q

What happened to the ability of a Halogen to act as a reducing agent down a group?

A

INCREASES
- size of halogen increases
- outer electron is further from nucleus
- less attraction between nucleus ant outer electron so they lose an electron easily

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11
Q

How can you test the reducing ability of Halide ions?

A

an acid base reaction
by reacting solid halide salts with concentrated sulphuric acid

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12
Q

What is the equation for a halide salt with sulphuric acid?

A

NaX + H2SO4 > NaHSO4 + HX

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13
Q

What is the observation for HX

A

misty fumes

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14
Q

What reaction does F- (NaF) undergo?

A

not a strong reducing agent so only does an acid base reaction

NaF + H2SO4 > NaH2SO4 + HF
misty fumes

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15
Q

What reaction does Cl- (NaCl) undergo?

A

only undergo acid base reaction
stronger than fluorine but still not strong enough to reduce the sulphuric acid

NaCl + H2SO4 > NaH2SO4 + HCL
misty fumes

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16
Q

What reactions do Br- (NaBr) undergo?

A

Both acid base reaction and redox
stronger reducing agents than Cl ions

It reduces H2SO4 to SO2

17
Q

What observations come from Br- redox reaction?

A

Choking gas - SO2
Brown gas - Br2

18
Q

What is the equation for Br- redox reaction?

A

2e- + 2H+ + H2SO4 > SO2 + 2H2O
2Br- > Br2 + 2e-

2H+ + H2SO4 + 2Br > Br2 + SO2 + 2H2O

19
Q

What reactions does I- (NaI) undergo?

A

Acid base reaction
and 3 redox rection

reduces H2SO4 to, H2S, SO2 and S

20
Q

What are the observations in each redox reaction with I-

A

SO2 - choking gas
H2S - rotten egg smell
S - yellow solid
I2 - black solid and purple gas

21
Q

How can you identify Halides in a solution?

A

using acidified silver nitrate

22
Q

What is the full and ionic equation for a Halide with silver nitrate?

A

full
AgNO3 + NaX > AgX + NaNO3

ionic
Ag+(aq) + X-(aq) > AgX

23
Q

What are the observations with Halide ions and silver nitrate?

A

AgF = NVC insoluble
AgCl = white ppt
AgBr = cream ppt
AgI = yellow ppt

24
Q

Why should Hydroxide and carbonate ions be removed before testing with Ag?

A

they both form a ppt in Ag and will interfere with the reaction

25
Q

What is the equation for removing carbonate ions using nitric acid?

A

2HNO3 + Na2CO3 > 2NaNO3 + CO2 + H2O

ionic
2H+ + CO3(^2-) + H2O + CO2

26
Q

What is the trend in solubility in DILUTE NH3 down group 7?

A

decreases from AgCl to AgI
AgI is insoluble

27
Q

What is the equation for AgCl in dilute NH3?

A

AgCl(s) + 2NH3(aq) > Ag(NH3)2+(aq) + Cl-

28
Q

What is the trend in solubility in CONCENTRATED NH3?

A

AgBr is soluble
AgI is insoluble

29
Q

What is the equation for AgBr in concentrated NH3

A

AgBr(s) + 2NH3(aq) > Ag(NH3)2+(aq) + Br-(aq)

30
Q

What is the equation for chlorine dissolving in water?

A

Cl2(g) + H2O ⇆ HCl(aq) + HClO(aq)

31
Q

What id a disproportionatiom reaction?

A

when an atom goes through is both oxidised AND reduced

32
Q

What happened when universal indicator paper is added to chlorine water?

A

turns red first - both reaction products are acids

then it turns white as HClO is an effective bleach

33
Q

What happenes when chlorine is bubbled in water in prescense of sunlight?

A

a colourless gas is produced and the green colour due to chlorine fades

chlorine oxidises water to O2 and chlorine is reduced to chloride

34
Q

What is the equation for Cl and H2O in sunlight?

A

2Cl2 + 2H2O > 4HCl + O2

35
Q

What is the use of chlorine in water treatment?

A

sterilises water for swimming pools
kills bacteria

36
Q

What is the equation for the reaction with Chlorine and cold dilute sodium hydroxide?

A

Cl2 + 2NaOH > H2O + NaCl + NaClO

37
Q

What is the use of NaClO?

A

active ingredient in house bleach

chemistry (14 decks)

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