This question is about the reactions of the halogens and halide ions.
☐ | A | oxidation only | |
☐ | B | reduction only | |
☐ | C | redox | |
☐ | D | disproportionation |
[Density: aqueous layer solution = 1.10 gcm–3, cyclohexane layer = 0.78 gcm–3]
The colour of the lower layer was
☐ | A | pale yellow | |
☐ | B | purple | |
☐ | C | red | |
☐ | D | pale green |
Concentrated sulfuric acid was added to a small quantity of solid potassium iodide in a test tube.
(1)
☐ | A | hydrogen iodide and sulfur dioxide only | |
☐ | B | hydrogen iodide and hydrogen sulfide only | |
☐ | C | hydrogen iodide, sulfur dioxide and hydrogen sulfide | |
☐ | D | hydrogen iodide, hydrogen sulfide and iodine |
State the observation when the hydrogen iodide gas is passed over the mouth of an open bottle of concentrated ammonia solution.
Write an equation, including state symbols, for the reaction.
Potassium iodate(V) can be prepared by adding solid iodine to a hot aqueous solution of potassium hydroxide.
The equation for the reaction is
3I2 + 6KOH → KIO3 + 5KI + 3H2O
Potassium iodate(V) can be separated from the other reaction product using their differing solubilities in water.
Solubility in water at 25 °C / mol dm–3 |
|
KI | 8.92 |
KIO3 | 0.43 |
(3)
(2)
Fluorine is an element in Group 7.
Group 7 includes the elements chlorine, bromine and iodine.
Some information about the melting and boiling temperatures of Group 7 elements is shown in the table.
Element | Melting temperature / K | Boiling temperature / K |
chlorine | 172 | 238 |
bromine | 266 | 332 |
iodine | 387 | 457 |
Which is the expected boiling temperature of fluorine, in kelvin, K?
☐ | A | 4 | |
☐ | B | 85 | |
☐ | C | 575 | |
☐ | D | 610 |
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