794410
Description
Flashcards by Matt Storey, updated more than 1 year ago
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Created by Matt Storey
over 10 years ago
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| Question | Answer |
| What are the 5 group 7 halogen molecules? Give a description of the first four at room temperature | Fluorine (pale yellow gas), chlorine (green gas), bromine (red/brown liquid), iodine (black solid) |
| What is the trend in atomic radii as we go down group 7? | It increases as each new element gains an extra energy level |
| What is the trend in electronegativity as we descend group 7? | It decreases because element gains another energy level which means the outer electrons are further away from the nucleus and there is increased shielding |
| What is the trend in melting point as you go down group 7? | It increases as the atoms have more electron which increases the strength of the van der waals force holding them together |
| What is the trend in oxidising ability of the group 7 elements as we go down the group? | It decreases because the atoms become bigger and increased shielding means they have cannot reduce other elements as easily. Fluorine is the most reducing element. |
| What happens to the group seven halides in a redox reaction? | They gain electrons are reduced meaning they act as good oxidising agents |
| What is a displacement reaction between halogens? | Halogens react in a solution in such a way that a halide in a compound will be displaced by a more reactive halogen |
| Fluorine will displace bromine in a compound. True of False? | True.as fluorine is more reactive than bromine |
| A halide will always be displaced in a compound by halogen above, or below it in the periodic table? | Above as there is a decrease in reactivity down group seven and halide ions are always displaced by halogens which are more reactive then themselves |
| Halide ions cannot act as reducing agents true or false? | False, halide ions can give away electrons to form neutral halogen molecules |
| What compound do all sodium halides react with? | Sulphuric acid (H2SO4) |
| When sodium chloride reacts with sulphuric acid 1.What is observed? 2.What are the products? 3.What type of reaction occurs? | 1.Steamy fumes of hydrogen chloride 2.Solid sodium hydrogen sulfate 3. Acid Base reaction (no change in any oxidation state) |
| Bromine is a stronger reducing agent than chlorine and fluorine, hydrogen bromide oxidises the oxidation state of sulphur in sulphuric acid from +6 to what? And what products does the sulphur form? | From +6 to +4 and forms sulphur dioxide |
| Hydrogen iodide can oxidise sulphuric acid to three different oxidation states, what are these oxidation states and in what compound does sulphur have these oxidation states? | From+6 to +4 forming sulphur dioxide. Then to 0 forming sulphur. The to -2 forming hydrogen sulfate |
| What is observed when reacting sodium iodide and sulphuric acid? | Steamy fumes of hydrogen iodide, black solid iodine formed, solid yellow sulphur and strong egg smell of hydrogen sulphide gas |
| What forms when metal halides react with silver ions in aqueous solution? | Insoluble silver halide precipitate formed |
| Why does silver fluoride not form a precipitate? | It is insoluble in water |
| Why is dilute nitric acid added to a halide solution before performing a silver test? | To remove any hydroxide or carbonate impurities which may interfere with the test by forming insoluble silver carbonate or insoluble silver hydroxide |
| What are the distinguishing colours of each of the silver halide precipitates? | Silver fluoride forms no precipitate. Silver chloride forms a white precipitate, silver bromide forms a cream precipitate and silver iodide forms a yellow precipitate |
| Since the colours of the silver halides are similar how can we distinguish between them using ammonia? | Silver chloride dissolves in dilute ammonia, silver bromide dissolves in concentrated ammonia, silver iodide does not dissolve in concentrated ammonia |
| What products are formed when chlorine reacts with water in a reversible reaction | Chloric(1) acid and hydrochloric acid |
| What is a disproportionation reaction? | A reaction in which the oxidation of some atoms increase and others decrease |
| What are the properties of chloric (I) acid? | Acid, oxidising agent kills bacteria acts as a bleach |
| What is formed when chlorine reacts with water in the presence of sunlight? | Hydrochloric acid is formed meaning chlorine is rapidly lost from pools in the sunlight |
| How can pools be chlorinated instead of using direct chlorination? | Add solid sodium chlorate which in water forms chloric (I) acid however acid is levels are maintained |
| What forms when chlorine reacts with cold sodium hydroxide? | Sodium chloride and sodium chlorate (I) this is another disproportionation reaction |
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