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Estimate the volume of a water molecule using the data of one molecule( density of water = 1000kg //m^3)What is its approximate size? |
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Answer» Solution :In the liquid (or solid) phase, the molecules of water are quite closely packed. The density of water MOLECULE MAY therefore, be REGARDED as roughly equal to the density of bulk `"water" = 1000 kgm^(-3)`. To estimate the volume of a water molecule, we need to know the mass of a single water molecule. We know that 1 MOLE of water has a mass approximately equal to (2 + 16)g = 18 g = 0.018 kg. Since 1 mole contains about `6 xx 10^(23)` molecules (Avogadro.s number), the mass of a molecule of water is `(0.018)//(6 xx 10^(23)) "kg" = 3 xx 10^(-26)` kg. Therefore, a rough estimate of the volume of a water molecule is as follows: `"Volume of a water molecule" = (3 xx 10^(-26) "kg")// (1000 "kg" m^(-3) )` `= 3 xx 10^(-29) m^(3)` ` = (4//3) pi (Radius)^(3)` Hence, `"Radius" ~~ 2 xx 10^(-10) m = 2 Å` |
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