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Homework Help: Properties Of ionic and covalent

  1. Jun 22, 2006 #1
    Which properties concerning ionic compounds and covalent molecules are INCORRECT? pick 3 statements.

    A.) All ionic compounds are soluble in water.
    B.) All covalent molecules are INSOLUBLE in water.
    C.) Covalent molecules are usually soluble in organic solvents.
    D.) Covalent molecules have high volatility but low boiling points. Thus, at
    room temperature, they are usually liquids or gases.
    E.) Covalent molecules can only conduct electricity in the molten state.

    i pick A, B and E for incorrect statements.
    does anybody disagree?
    Initially i thought that all covalent molecules are INSOLUBLE in water. is that true?
  2. jcsd
  3. Jun 22, 2006 #2
    I would also pick A, B, and E. Some covalent molecules are soluble in water- examples include sugar and ethanol so B is incorrect. If you really want to split hairs, you could argue that A is actually a correct statement because all ionic compounds are soluble in water to some degree. These "insoluble" ionic compounds have a solubility product constant that describes how much dissolves. These constants are very low and can range from 10^-3 to 10^-100. However, a substance is commonly defined as "insoluble" if less than 0.01 mol dissolves per liter of water. So that's why I'd still pick A.
  4. Jun 23, 2006 #3


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    Staff Emeritus
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    The lesson to take away from this question (more than the chemistry involved) is to be very wary of statements that use words like all, always, only, never, etc.
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