1.
18) Explain why oil and water do not mix. A) Water is not able to ionize in oil. B) The dipole-
dipole force between water and oil molecules is too strong. C) Water molecules are polar and oil
molecules are not polar D) Oil molecules cannot break the ionic bonds in water E) The viscosity
of oil doesn't allow mixing of the water molecules. 19) Place the following aqueous solutions of
nonvolatile, nonionic compounds in order ot decreasing (highest to lowest) osmotic pressure. I.
0.011 M sucrose II. 0.00095 M galactose III. 0.0060 M glycerin A)I > 111 >11 C) II > III >I 20)
Why isn't pentanol (CH3CH2CH2CH2CH2OH) very soluble in water? A) Pentanol cannot
engage in hydrogen-bonding interactions. B) Pentanol is too viscous so it cannot mix with water.
C) Pentanol's ion-dipole interactions with water are not strong enough. D) Most of the pentanol
molecule is nonpolar, so it exhibits mainly dispersion forces, making it difficult to dissolve in
water. E) Most of the pentanol molecule is polar, so it exhibits mainly dipole-dipoles forces
making it difficult to dissolve in water.
Solution
Ans 18 : C) Water molecules are polar and oil molecules are not polar
Since water molecule are polar and oil molecules are non polar, they are attracted to each other
more than the other oil molecules , in accordance with the general solubility rule that "like
dissolves like". Moreover oil being less denser than water , floats over the top of water surface .