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    Hey im not doing gcse's any more but i am a science tutor and i have got a question but the book doesnt give an answer and i cant work it out.

    The question goes;
    Explain which of potassium bromide (KBr) and calcium oxide (CaO) has the higher melting point.

    How would you answer this, and work it out?
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    (Original post by hollyjw)
    Hey im not doing gcse's any more but i am a science tutor and i have got a question but the book doesnt give an answer and i cant work it out.

    The question goes;
    Explain which of potassium bromide (KBr) and calcium oxide (CaO) has the higher melting point.

    How would you answer this, and work it out?
    This is a question about thermal stability.
    Basically both are ionic compounds.
    But in KBr, you have K+ and Br- ions.
    Whereas in CaO, you have Ca2+ and O2- so there are stronger forces of electrostatic attraction between those two ions, because they have double the charge, than between K+ and Br-.
    Stronger forces of attraction = more energy needed to break bonds = higher temps.
 
 
 
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