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    1) Why is the magnitude of the lattice enthalpy of three Group halids decreasing in the order NaF > NaCl > KCl?

    2) Butan-1-ol was converted into butyl propanoate by the reaction with an excess of propanoic acid. In the reaction, 6.0g of the alcohol gave 7.4g of the ester the percentage yield of ester was...

    A) 57
    B) 70
    C) 75
    D) 81

    (would appreciate the method with the answer for this question)


    1. NaF to NaCl involved a larger anion, and lattice enthalpy increases as the sum of the ionic radii increases. this is because the force of attraction is weaker when the charges are further apart (the two ions), and so less energy can be gained from the formation of the bond.

    NaCl to KCl is the same, except this time the cause of the larger ionic radii sum is the larger cation. Again this reduces lattice enthalpy.

    2. One mole of butan-1-ol reacts in a 1 to 1 ratio to form one mole of the ester. 6.0g of butan-1-ol, of RMM 74, is 6/74 moles. This forms 6/74 moles of the ester, RMM 130, which is (6/74)*130 = 10.54g. 7.4g of this is 7.4/10.54 = 70.2%, so the answer is B.
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