Question

Q- On the basis of hydrogen bonding, explain why ice floats on water, whereas solid lead sinks in liquid lead.

Answer 1

Ice is less dense than water because of its intermolecular forces. Water contains hydrogen bonds ( inter molecular hydrogen bond) A hydrogen bond fromed between more electronegative atom (o,N,F) and hydrogen atom. As the water gets colder and the kinetic energy of the molecules decreases the hydrogen bonds keep the water molecules apart, forming hexagonal structures with water molecules at each vertex. In between the water molecules in nothing. In liquid water the molecules of water can be much closer together, the hydrogen bonds are more flexible. Therefore the solid ice with its molecules kept at a fairly fixed distance and the crystals holding lots of nothing among the water molecules is less dense than the liquid water.

solid lead has more density than liquid lead.Here liquid lead no hydrogen bonds. So solid lead sinks in liquid lead.