What is the effect of temperature on the solubility of ammonia(NH3) in water?

Answer 1

For most gases including ammonia their solubility decreases with temperature.

The solubility of gases, like other solubilities, can increase or decrease with temperature. A simple model can be used to explain why gases can behave either way, depending on the gas and the solvent. The heat absorbed or released when a gas dissolves in liquid has essentially two contributions:


Energy is absorbed to open a pocket in the solvent. Solvent molecules attract each other. Pulling them apart to make a cavity will require energy, and heat is absorbed in this step for most solvents. Water is a special case- it already contains open holes in its network of loose hydrogen bonds around room temperature. For water, very little heat is required to create pockets that can hold gas molecules.

Energy is released when a gas molecule is popped into the pocket. Intermolecular attractions between the gas molecule and the surrounding solvent molecules lower its energy, and heat is released. The stronger the attractions are, the more heat is released. Water is capable of forming hydrogen bonds with some gases, while organic solvents often can't. A larger amount of heat is released when a gas molecule is placed in the pocket in water than in organic solvents.
There is usually net absorption of heat when gases are dissolved in organic solvents, because the pocket-making contribution is bigger. Le Chatelier's principle predicts that when heat is absorbed by the dissolution process, it will be favored at higher temperature. Solubility is expected to increase when temperature rises.
There is usually net release of heat when gases are dissolved in water, because the pocket-filling contribution is biggest. Solubility is expected to decrease when temperature rises.

Answer 2

Generally speaking, gases are less soluble in water the higher the temperature. This is true of ammonia.

(Solubility of gases is one of the big concerns associated with global warming - less oxygen dissolved in the oceans so organisms suffocate. Also, since we believe that the oceans have been taking up quite a bit of CO2, if they warm up to the point at which the gas becomes less soluble, it will be released into the atmosphere, warming up the planet even more in a positive feedback loop.)

Answer 3

After dissolving a heterogenious mixture with H2O, the temperature of NH3 goes minutely higher than its original temperature.
It goes up by 3.5 calories!!!!!!!!!!!!!!!