• Question: Why do different liquids have different boiling points?

    Asked by olleym09 to Stu, Martin, Mark, Jenni, Helen on 23 Jun 2011.
    • Photo: Jenni Tilley

      Jenni Tilley answered on 21 Jun 2011:

      Boiling (turning liquid into gas) happens when enough energy is provided to break the bonds between the atoms so that they can move apart. Some atoms are more strongly bound together so it’s difficult to pull them apart and more energy (higher temperature) is needed.

      Did you know that pessure also plays a role in this? If there’s less pressure around the liquid, it’s easier for the atoms to be pulled apart and fly off into the gas. That’s why water boils at a lower temperature at the top of everest.

      This also explains why watefreezes at different temperatures when we add salt or sugar to it – do you know why?

    • Photo: Helen O'Connor

      Helen O'Connor answered on 23 Jun 2011:

      I didn’t know the answer to this, but Jenni’s was really helpful. I then looked up why water freezes at different temperatures when we add salt to it – apparently with salt added, the boiling point of water INCREASES and the freezing point of water DECREASES! I still don’t know why though. I need to do a lot of googling to find that out.

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