Saved Bookmarks
| 1. |
Estimate the volume of a water molecule using the data in Example 13.1. |
|
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` |
|