Alkanes 0.0 / 5 ? ChemistryFunctional GroupsA2/A-levelAQA Created by: izzybook25Created on: 30-04-18 17:04 What is the formula for an alkane? CnH2n+2 1 of 25 What is the formula for a ring alkane? CnH2n 2 of 25 When do alkanes have isomers? After butane 3 of 25 Why are alkanes non polar? There's little difference in polarity between carbon and hydrogen 4 of 25 What intermolecular forces occur in alkanes? Weak van de waals 5 of 25 What makes van de waals forces increase? Increased chain length 6 of 25 What also increases due to increased chain length? Boiling point 7 of 25 What length chain is a gas? 1+ 8 of 25 What length chain is a liquid? 5+ 9 of 25 What length chain is a solid? 18+ 10 of 25 Why are alkanes insoluble? Hydrogen bond in H2O is stronger than the van de waals foces in alkanes 11 of 25 What do alkanes react with? Oxygen and halogens in suitable conditions 12 of 25 How is fractional distillation carried out? Crude oil heated, gases condense when they reach tray at lower temp than their boiling point 13 of 25 Where do short and long chains condense? Short at the top, long/thick at the bottom 14 of 25 What is thermal cracking? Carbon - carbon bond is broken, 1 electron from the bond goes to each atom creating a free radical 15 of 25 What conditions are needed for thermal cracking? High temp (1200K) and high pressure (7000kPa) 16 of 25 What is the main problem with thermal cracking? Chains don't always break in the middle meaning H2 and alkenes can be formed 17 of 25 How long are alkanes kept under these conditions for? 1 second 18 of 25 What is required for catalytic cracking? Low temperature, low pressure and a zeolite catalyst 19 of 25 What is a zeolite catalyst? Silicum dioxide and aluminum oxide honeycomb structure catalyst 20 of 25 What does catalytic cracking produce? Motor fuels 21 of 25 What is combustion? Alkanes burn completely in oxygen 22 of 25 What is produced from combustion? Carbon dioxide and water 23 of 25 What is incomplete combustion? When alkanes burn in a limited oxygen supply 24 of 25 What is produce from incomplete combustion? Carbon monoxide and soot if there's very little oxygen 25 of 25
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