group 7 Flashcards
what is the physical property of flourine?
- pale yellow gas
- very reactive
- toxic
what is the physical property of chlorine?
- green gas
- very reactive
- poisonous in high concentration
what is the physical property of bromine?
-red liquid
-gives off dense brown/orange poisonous fumes
-often used as a solution in water called bromine water
what is the trend in melting point and boiling point in group 7?
-increases down the group
-more electrons
-larger VDW forces between molecules
-intermolecular force gets larger
-no PD-PD because it has the same element so it cancels out
what is the trend in electronegativity down in group 7?
- decreases
- bigger atoms/ more shells
- more shielding
- weaker attraction between nucleus and 2 electrons in covalent bonds
what is the trend in atomic radius down the group?
- increases
- more shells
- bigger atoms
what is the trend in 1st ionisation?
- decreases
- atoms gets bigger/more shells
- mores shielding
- weaker attraction from nucleus to electron in outer shell
what is the physical property of iodine?
- grey crystals
-reactive
-toxic
-easily turns into purple vapour on heating
-used in solution as antiseptic
what is the effect of a halogen that is strong oxidising agent on a halogen with a lower oxidising power?
it will displace the weaker halogen from one of its compounds
how does oxidising strength change down the group of halogens?
the oxidising strength decreases
what role do oxidising agents play in chemical reactions?
they are electron receptors
what would chlorine displace?
- bromine ions
- iodine ions
what would bromine displace?
- iodine ions
what would the reaction Cl2 and potassium chloride form?
Very pale green
solution, no
reaction
what would the reaction Br2 and potassium chloride form?
Yellow solution, no
reaction
what would the reaction iodine and potassium chloride form?
Brown solution,
no reaction
what would the reaction potassium bromide and chlorine form?
Yellow solution, Cl
has displaced Br
what would the reaction potassium bromide and bromide form?
Yellow solution, no
reaction
what would the reaction potassium bromide and iodine form?
Brown solution,
no reaction
what would the reaction potassium iodide and chlorine form?
Brown solution, Cl
has displaced I
what would the reaction potassium iodine and bromine form?
Brown Solution, Br
has displaced I
what would the reaction potassium iodine and iodine form?
Brown Solution,
no reaction
what is the colour of chlorine?
very pale green often colourless
what is the colour of iodine?
brown solutions sometimes black solid present
what is the colour of bromine?
yellow solution
what do you react with halide ions to determine which halide ions are present?
silver nitrate
what is the role of nitric acid?
-to react with any carbonates present to prevent the formation of the precipitate Ag2CO3
-This would mask the desired observations
2 HNO3 + Na2CO3 → 2 NaNO3 + H2O + CO2
do fluorides produce a precipitate?
no
what colour precipitate does chloride produce? including chemical equation
-white
-Ag+(aq) + Cl-(aq) → AgCl(s)
what colour precipitate does bromides produce? include chemical equation
-cream precipitate
-Ag+(aq) + Br- (aq) → AgBr(s)
what colour precipitate does iodide produce and include chemical equation
- yellow precipitate
-Ag+(aq) + I- (aq) → AgI(s)
what can silver halide be treated with to differentiate the colours if it looks similar?
- silver chloride dissolves in dilute ammonia to form a complex ion : colourless solution
- silver bromide dissolves in concentrated ammonia to form a complex ion: colourless solution
-silver iodide does not react with ammonia because its too insoluble
What happens to the reducing power of halides as you move down group 7?
The reducing power of the halides increases down group 7.
Why do halides become stronger reducing agents as their ionic size increases?
As the ions get bigger, it is easier for the outer electrons to be given away due to a smaller pull from the nucleus.
What type of reactions occur when fluoride and chloride react with concentrated sulfuric acid?
Only acid-base reactions occur, not redox reactions.
What are the observations when NaF reacts with H2SO4?
White steamy fumes of HF are evolved.
NaF(s) + H2SO4(l) → NaHSO4 (s) + HF(g)
What are the observations when NaCl reacts with H2SO4?
White steamy fumes of HCl are evolved.
NaCl(s) + H2SO4 (l) → NaHSO4 (s) + HCl(g)
What is the initial reaction type when bromide ions react with concentrated sulfuric acid?
Acid-base reaction.
What observations are made when bromide ions react with sulfuric acid?
White steamy fumes of HBr and orange fumes of bromine are evolved, along with a colourless, acidic gas SO2.
Fill in the blank: A reducing agent ______ electrons.
donates
True or False: Fluoride ions are strong enough reducing agents to reduce sulfur in H2SO4.
False
What role does H2SO4 play in the reactions with fluoride and chloride?
H2SO4 acts as an acid (proton donor).
Which halide ions are stronger reducing agents than fluoride and chloride?
Bromide ions.
What is the reduction product formed from the redox reaction involving H₂SO₄?
sulfur dioxide
In the given reactions, sulfur dioxide (SO₂) is produced as a reduction product.
What role does H₂SO₄ play in the first step of the reaction?
acid
H₂SO₄ acts as an acid producing HI in the first step.
What is the strongest halide reducing agent mentioned?
I- ions
Iodide ions (I-) are noted for being the strongest halide reducing agents.
What does the reaction NaI(s) + H₂SO₄(l) produce?
NaHSO₄(s) + HI(g)
This reaction shows the interaction of sodium iodide with sulfuric acid.
What gas is evolved that has a bad egg smell during the reaction?
H₂S
Hydrogen sulfide (H₂S) is known for its characteristic unpleasant odor.
What are the observations when HI is evolved in the reaction?
White steamy fumes of HI, black solid and purple fumes of iodine, colorless acidic gas SO₂
These observations highlight the various products formed in the reaction.
True or False: H₂SO₄ acts as both an acid and an oxidizing agent in these reactions.
True
H₂SO₄ first acts as an acid and then as an oxidizing agent in the redox steps.
What is disproportionation?
A reaction where an element simultaneously oxidises and reduces.
What is the reaction of chlorine with water?
Cl2 (g) + H2O (l) = HClO (aq) + HCl (aq)
What happens when a universal indicator is added to the chlorine-water solution?
It first turns red due to acidity, then turns colourless as HClO bleaches the colour.
What occurs when chlorine is bubbled through water in bright sunlight?
Cl2 + 2H2O → 4H+ + 4Cl- + O2
What is produced when chlorine reacts with water in sunlight?
A colourless gas (O2) and the greenish colour of chlorine water fades.
What is the purpose of chlorine in water treatment?
To kill bacteria and treat drinking water and swimming pools.
What is the reaction of chlorine with cold dilute NaOH solution?
Cl2 (aq) + 2 NaOH (aq) → NaCl (aq) + NaClO (aq) + H2O (l)
What happens to the colour of the halogen solution when it reacts with cold dilute NaOH?
The colour fades to colourless.
What is the mixture of NaCl and NaClO used for?
As bleach and to disinfect/kills bacteria.
True or False: Chlorine’s health benefits in water treatment outweigh its toxic effects.
True
What is the reaction of chlorine with cold dilute NaOH solution?
Cl2 (aq) + 2 NaOH (aq) → NaCl (aq) + NaClO (aq) + H2O (l)
The color of the halogen solution will fade to colorless.
What is the mixture of NaCl and NaClO used for?
Used as bleach and to disinfect/kills bacteria.
What are the IUPAC naming conventions for compounds containing sulfur and chlorine with oxygen?
Called sulfates and chlorates with relevant oxidation number given in Roman numerals.
what is the name of NaClO
sodium chlorate I
what is the name of NaClO3
sodium chlorate (V)
what is the name of K2SO4
potassium sulfate (VI)
what is the name of K2SO3
potassium sulfate (IV)
Fill in the blank: The reaction of chlorine with sodium hydroxide produces _______ and NaClO.
NaCl
True or False: The color of chlorine solution remains unchanged when reacted with cold dilute NaOH.
False
