Why does the solid state of water (ice) has a lower density and a greater volume than its liquid form?
thank you
Answer:
Water actually has a quirky property... The decrease in the density of ice is more attributed to molecules (mass) per unit volume, and not to volume itself.
But why?
When you cool water to 4 degrees Celcius (where it is at its densest), some of the water molecules start to lose kinetic energy and becomes attracted to each other by hydrogen bonds forming small structures, while some water molecules becomes "trapped" into these structures. As you look into a given volume, you see that the molecules becomes constricted to these structures, causing more molecules (and more mass) to be constricted into these smaller volumes (remember that density=mass/volume) and making density higher. Contrast this with water at room temperature where molecules are more dispersed, leaving fewer molecules than unit area...
What accounts for the apparent density of the ice?
As it is cooled to temperatures lower than 0 degrees centigrade, the water molecules forms a highly ordered structure by hydrogen bonds (which also prevents molecules from getting too close to each other), leaving empty spaces between structures, leaving less molecules per unit volume, (which is much lower than that for water at room temperature), and decreasing the density.
The increased volume as perceived is probably due to the distribution of the water molecules within the crystal structure (with the presence of hollow portions within these structures), which due to the stability of hydrogen bonds, forms a solid structure.
Usually we have the reverse that is the solid state has lessvolume than the liquidstate.Butfor water the reverse is true .This is due to the fact that in water the central atom that is the oxygen has two lone pairs so oriented that the extent of hydrogen bonding is maximum in case of ice. Due to this therefore there is a much void space(to generate the maximum of hydrogenbonding). Now as we heat the ice the hydrogen bonds get disrupted and the void spaces become filledupwith the water molecules.Thus the liquid formhas more density&less volume than the solid state.
Why is because it keeps fish alive in the deep rivers and lakes in the bitter cold of winter.
because of hydrogen bonding ,ice form open cage structure . due to this , the volume of ice increases &density decreases.
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