Group 7 0.0 / 5 ? ChemistryThe Periodic TableA2/A-levelAQA Created by: izzybook25Created on: 26-04-18 19:46 What form group 7 molecules exist in? Diatomic molecules 1 of 26 Why do group 7 molecules have high boiling points? Many electrons create strong van de waals forces meaning more energy is required to break them 2 of 26 Why does electronegativity decrease going down the group? Atomic radius and shielding 3 of 26 Are group 7 molecules oxidising or reducing agents? Oxidising agents 4 of 26 What do group 7 molecules dissolve in? Water and non-polar solvents (cyclohexane) 5 of 26 What colour is formed when chlorine is dissolved in water and cyclohexane? Pale green 6 of 26 What colour is formed when bromine is dissolved in water and cyclohexane? Orange 7 of 26 What colour is formed when iodine is dissolved in water and cyclohexane? Brown in water, violet in cyclohexane 8 of 26 What is a halide? A halogen which has gained electrons to form negatively charged ions 9 of 26 Why is reactivity increased when going down halides? Larger halides can lose electrons more easily due to less attraction to nucleus, therefore they have increased reducing ability 10 of 26 What do sodium halides react with? Concentrated sulfuric acid 11 of 26 What happens when sodium chloride reacts with concentrated sulfuric acid? Acidic gas given off, hydrogen halide given off 12 of 26 What is the contents of the test tube? White solid 13 of 26 What products are formed from this reaction? Sodium hydrogen sulphate, hydrogen chloride gas 14 of 26 What happens when sodium bromide reacts with concentrated sulfuric acid? Bromide ions reduce H2SO4 to create a 2nd exothermic reaction, white fumes, chocking acidic gas, hydrogen halide gas, acidic gas 15 of 26 What is the contents of the test tube? White solid, orange liquid 16 of 26 What products are formed from this reaction? Sodium hydrogen sulphate, hydrogen bromide gas, bromine, sulfur dioxide 17 of 26 What happens when sodium bromide reacts with concentrated sulfuric acid? Iodide ions further reduce, acidic gas, purple vapour, egg smell, hydrogen halide gas 18 of 26 What is the contents of the test tube? Black solid, yellow solid 19 of 26 What products are formed from this reaction? Sodium hydrogen sulphate, hydrogen iodide, iodine, sulfur, hydrogen sulfide 20 of 26 How do you test for halide ions? Add nitric acid to remove carbonates, add silver nitrate to form coloured precipitate, add dilute ammonia, add concentrated ammonia if not dissolved 21 of 26 How do we know it's chloride? Forms white precipitate, dissolves in dilute ammonia 22 of 26 How do we know it's bromide? Cream precipitate, dissolves in concentrated ammonia 23 of 26 How do we know it's iodide? Yellow precipitate, doesn't dissolve 24 of 26 A reaction where an element is oxidised and reduced is called a Disproportionation reaction 25 of 26 What can chlorine make in disproportionation reactions? Water treatment and bleach 26 of 26
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