Question

What weight of sodium nitrate will separate when a saturated solution containing\[50g\] of water is cooled from \[{50^o}C\] to \[{30^o}C\]? The solubility of \[NaN{O_3}\]at \[{50^o}C\] and \[{30^o}C\] is \[114g\] and \[86g\] respectively.

Answer 1

Hint: As we know that the water is an inorganic compound which does not have any taste and odor. And the water is a volatile liquid which is transparent in nature. The particles present in the liquid are far apart. Hence, it can easily move very easily due to the less intermolecular attraction between the particles. And sodium nitrate is a chemical compound having the molecular formula, \[NaN{O_3}\]. The components present in the sodium nitrate are sodium, nitrogen and oxygen. The oxidation number of nitrogen in sodium nitrate is equal to \[ + 5\]. Here, the negative charge is equal to positive charge.

Complete answer:
According to the question,\[100g\] of water is soluble in \[114g\] of \[NaN{O_3}\] at \[{50^o}C\] and \[114g\] of sodium nitrate at \[{30^o}C\].
Hence, from this we can say that, one gram of water will dissolve in \[1.14g\] of sodium nitrate at \[{50^o}C\] and \[0.86g\] of sodium nitrate at \[{30^o}C\].
Therefore, next we have to find out the weight of sodium nitrate at \[{50^o}C\] to dissolve \[50g\]of water.
Weight of sodium nitrate\[ = 1.14 \times 50 = 57g\]
The weight of sodium nitrate at \[{30^o}C\] to dissolve \[50g\] of water \[ = 0.86 \times 50 = 43g\]
 Because of decreasing solubility of sodium nitrate in water with respect to the temperature, there is a separation of sodium nitrate out of saturated solution. Therefore, the weight that will be differentiated from the \[50g\] of water\[ = 57 - 43 = 14g\]
Hence, the weight of sodium nitrate will separate when a saturated solution containing\[50g\]of water is cooled from \[{50^o}C\] to \[{30^o}C\] be equal to \[14g\].

Note:
We need to remember that the solubility of a compound changes with temperature. Maybe the solubility increases with increasing temperature, or it decreases with increasing temperature. In the case of gas, when the kinetic energy of gaseous solute increases, there is a greater tendency to return to the gaseous phase by escaping the attraction of the molecules of solvent.