Intermolecular forcesEdexcel A-Level Chemistry: Flashcards
What these 14 flashcards ask
- Which intermolecular force is present in all molecules?
- How do London forces arise?
- What makes London forces stronger?
- What is needed for hydrogen bonding?
- How many hydrogen bonds can one water molecule form?
- Why is ice less dense than water?
- Why does water have a high boiling temperature compared with H₂S?
- Why does boiling temperature rise as alkane chain length increases?
- Why do branched alkanes boil lower than straight-chain isomers?
- Why does ethanol boil higher than propane?
- Why is HF's boiling temperature higher than HCl's?
- Why does the boiling temperature rise from HCl to HI?
- Why does NaCl dissolve in water?
- Why is bromoethane insoluble in water?
Exam questions on Intermolecular forces
- Butane, pentane and hexane boil at about 0 °C, 36 °C and 69 °C respectively. An isomer of pentane, 2,2-dimethylpropane, boils at about 10 °C.Explain why the boiling temperature increases from butane to hexane.2 marks
- The boiling temperatures of the hydrogen halides are: HF 20 °C, HCl −85 °C, HBr −67 °C and HI −35 °C.Explain why the boiling temperature rises from HCl to HI, even though the bonds become less polar.2 marks
- Ice floats on liquid water. Water boils at 100 °C, whereas hydrogen sulfide, H₂S, which has a similar shape and more electrons, boils at about −60 °C.Explain why ice is less dense than liquid water.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).