Karteikarten
group 7
Karten in diesem Stapel (40)
- 1What is the trend in oxidising power of halogens as you go down the group?Oxidising strength decreases as you go down the group, remember, oxidising agents are electron acceptors.
- 2A halogen that is a strong oxidising agent will ______ a halogen with lower oxidising power from one of its compounds.displace
- 3What halides will chlorine displace?Bromides and iodides
- 4What halides will bromine displace?Iodides only
- 5What halides will iodine displace?None.
- 6What does the colour of the test tube show?Which free halogen is present in solution
- 7What halogen is present if the solution is very pale green (almost colourless)?Chlorine
- 8What halogen is present if the solution is yellowBromine
- 9What halogen is present if the solution is brown?Iodine
- 10What test is used to identify between halide ions?Acidified silver nitrate.
* nitric acid and then silver nitrate solution is added dropwise - 11Why is the silver nitrate solution acidified?To react with any carbonates present. If carbonates are present, Ag2CO3 will be formed, which would mask the desired observations.
- 12Write an equation to show how the nitric acid in the acidified silver nitrate solution would react with any carbonates present in the test tube2 HNO3 + Na2CO3 2 NaNO3 + H2O + CO2
- 13What happens when flourides are reacted with acidified silver nitrate?Colourless solution. No prepicitate is formed.
- 14What happens when clorides are reacted with acidified silver nitrate?White precipitate of AgCl (silver chloride) is formed
- 15What happens when bromides are reacted with acidified silver nitrate?Cream precipitate of AgBr (silver bromide) is formed
- 16What happens when iodides are reacted with acidified silver nitrate?Yellow precipitate of AgI (silver iodide) is formed
- 17With the acidified silver nitrate tests, what can you do to confirm your result if the colours of the precipitate look too similar?Add ammonia.
*DILUTE ammonia with AgCl goes colourless
AgCl(s) + 2NH3(aq) --> [Ag(NH3)2](aq) + Cl-(aq)
*CONCENTRATED ammonia with AgBr goes colourless
AgBr(s) + 2NH3(aq) [Ag(NH3)2]+(aq) + Br -(aq)
*AgI does not react with ammonia at all, it is too insoluble - 18What is the trend in solubility of silver halides in ammonia?Decreases as you go down the group
- 19What is the trend in reducing ability of halides?Increases as you go down the group. Remember good reducing ability means gives up its electrons easily
- 20How can the trend in reducing ability of halides be shown?By the reaction of solid sodium halides with concentrated sulphuric acid
- 21Which halides are not strong enough reducing agents to reduce S in H2SO4?F- and Cl- are not strong enough. Their solid halides do not undergo redox reactions with concentrated sulphuric acid. Only acid-base reactions as h2SO4 plays the role of an acid
- 22Give the equation and observation of solid sodium fluoride reacting with conc sulphuric acidNaF(s) + H2SO4(l) --> NaHSO4(s) + HF(g)
* White steamy fumes of HF are evolved
*not redox. OS of S does not reduce. acid-base only - 23Give the equation and observation of solid sodium chloride reacting with conc sulphuric acidNaCl(s) + H2SO4(l)-> NaHSO4(s) + HCl(g)
*steamy white fumes of HCl are evolved
*not redox. OS of S does not reduce. acid-base only - 24Give the equation and observation of solid sodium bromide reacting with conc sulphuric acidAcid- base step: NaBr(s) + H2SO4(l) -->NaHSO4(s) + HBr(g)
Redox step: 2HBr + H2SO4 --> Br2(g) + SO2(g) + 2H2O(l)
*steamy white fumes of HBr
*red fumes of Br2
*colourless acidic gas SO2 - 25Give the half equations of the redox reaction that occurs when NaBr reacts with conc sulphuric acidOx ½ equation: 2Br - Br2 + 2e
Re½ equation:H2SO4 + 2 H+ + 2 e- → SO2 + 2 H2O - 26what is the reduction product in NaBr and conc Na2SO?SO2 (colourless acidic gas)
- 27What are the observations for NaBr and conc sulphuric acid?1) Steamy white fumes of HBr
2) Red fumes of Br2
3) Colourless acidic gas SO2 - 28Which halide has the greatest reducing ability?Iodide
- 29Give the equations of what happens when solid sodium iodide reacts with conc sulphuric acid1) NaI(s) + H2SO4(l) --> NaHSO4(s) + HI (g)
2) 2 HI(g) + H2SO4 --> I2 + SO2 + 2 H2O
3) 6 HI(g) + H2SO4 --> 3 I2 + S + 4 H2O
4) 8 HI(g) + H2SO4 --> 4 I2 + H2S + 4 H2O - 30Give the observations for solid sodium iodide reacting with concentrated sulphuric acid1) White steamy fumes of HI
2) Colourless acidic gas SO2
3) Black solid/purple gas of I2
4) Yellow solid of S
5) Rotten egg smell of H2S - 31What is disproportionation?The name for a reaction in which an element simultaneously oxidises and reduces eg Cl2 + H2O --> HClO( aq) + HCl (aq)
- 32What products are formed when Cl2 reacts with water (normally)?* HClO (aq)
* HCl (aq) - 33Give the equation for then reaction of Cl2 with water (normally)Cl2 + H2O --> HClO( aq) + HCl (aq)
- 34Why is chlorine water slightly greenish?Because of the Cl2
- 35Why does the greenish colour of chlorine water fade?Because the Cl2 reacts and forms the colourless gas O2, as the equilibrium below forms:
2Cl2 + 2H2O --> 4H+ + 4Cl- + O2 - 36Give the reaction of Cl2 with water in bright sunlight2Cl2 + 2H2O --> 4H+ + 4Cl- + O2
*this is also the equilibrium that sets up in chlorine water - 37What are the uses of chlorine?* used to kill bacteria in swimming pools
* used to treat drinking water to kill bacteria - 38Cl2 is toxic. Why do we still use it?Its benefits outweigh its risk due to toxicity
- 39Give the reaction of aqueous chlorine with cold dilute NaOH solutionCl2 (aq) + 2NaOH(aq) NaCl (aq) + NaClO (aq) + H2O(l)
- 40Give the reaction and equation for the production of bleachAqueous chlorine with cold dilute NaOH solution
Cl2 (aq) + 2NaOH(aq) NaCl (aq) + NaClO (aq) + H2O(l)
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- Karteikarten am group 7, erstellt von Anushka John am 08/03/2017.
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- Anushka John
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