온도-용해도

 온도 - 용해도 곡선

 

 고체가 액체에 녹을 때, 고체가 고체에 녹을 때는 대체로 온도가 상승함에 따라 용해도가 증가하지만, 

 기체가 액체나 고체에 녹을 때는 기체 분자의 안정화 과정이 필요하기 때문에 (거리 감소 등) 온도가 낮아질수록 용해도가 증가한다. 

 

How Temperature Influences Solubility

The solubility of a substance is the amount of that substance that is required to form a saturated solution in a given amount of solvent at a specified temperature. Solubility is often measured as the grams of solute per 100 g of solvent. The solubility of sodium chloride in water is 36.0 g per 100 g water at 20°C. The temperature must be specified because solubility varies with temperature. For gases, the pressure must also be specified. Solubility is specific for a particular solvent. We will consider solubility of material in water as solvent.

The solubility of the majority of solid substances increases as the temperature increases. However, the effect is difficult to predict and varies widely from one solute to another. The temperature dependence of solubility can be visualized with the help of a solubility curve, a graph of the solubility vs. temperature (see figure below ).

 

Figure 1. Solubility curves for several compounds. From the CK-12 Foundation – Christopher Auyeung

 

Notice how the temperature dependence of NaCl is fairly flat, meaning that an increase in temperature has relatively little effect on the solubility of NaCl. The curve for KNO 3 , on the other hand, is very steep and so an increase in temperature dramatically increases the solubility of KNO 3 .

Several substances – HCl, NH 3 , and SO 2 – have solubility that decreases as temperature increases. They are all gases at standard pressure. When a solvent with a gas dissolved in it is heated, the kinetic energy of both the solvent and solute increases. As the kinetic energy of the gaseous solute increases, its molecules have a greater tendency to escape the attraction of the solvent molecules and return to the gas phase. Therefore, the solubility of a gas decreases as the temperature increases.

Solubility curves can be used to determine if a given solution is saturated or unsaturated. Suppose that 80 g of KNO 3 is added to 100 g of water at 30°C. According to the solubility curve, approximately 48 g of KNO 3 will dissolve at 30°C. This means that the solution will be saturated since 48 g is less than 80 g. We can also determine that there will be 80 – 48 = 32 g of undissolved KNO 3 remaining at the bottom of the container. Now suppose that this saturated solution is heated to 60°C. According to the curve, the solubility of KNO 3 at 60°C is about 107 g. Now the solution is unsaturated since it contains only the original 80 g of dissolved solute. Now suppose the solution is cooled all the way down to 0°C. The solubility at 0°C is about 14 g, meaning that 80 – 14 = 66 g of the KNO 3 will recrystallize.

출처: https://courses.lumenlearning.com/cheminter/chapter/how-temperature-influences-solubility/

How Temperature Influences Solubility | Chemistry for Non-Majors

 

 

보일러용어사전

기체 용해도

[ solubility of gas , 氣體溶解度 ]

보일러 관계에서 기체 용해도라고 하는 것은 물 속에 용해하는 산소나 탄산 가스 등의 기체가 어느 정도인가 하는 상태를 의미한다. 일정량의 수중에 용해하는 기체의 양은 수온이 일정하면 물에 접한 기체의 분압이 높을수록 기체 용해도는 증가하며, 물에 접한 기체의 분압이 일정하면 수온이 상승할수록 기체 용해도는 감소한다. 즉 「가스의 수중 용해도는 가스의 분압에 비례하고, 온도에 반비례 한다」고 하는 “헨리”의 법칙에 따른다. 1기압하에서의 탄산 가스(CO2)와 산소의 용해도를 나타내면 그림과 같이 된다. 보일러 부식 등의 원인이 되는 가스체 불순물은 헨리의 법칙을 응용하여 가열법이나 진공법, 기폭법(氣曝法)등에 의해 제거된다.

[네이버 지식백과] 기체 용해도 [solubility of gas, 氣體溶解度] (보일러용어사전, 2006. 1. 9., 일본보일러용어 연구회)