|
In nature, very little is elemental and pure. More often than not the stuff that made the Earth are impure in order to enable its use by living organisms. Plants extract minerals and water from the soil, and carbon dioxide from the air. If we were to drown them in water, nutrients, or pure CO2, they'd die in an instant.
Moderation is key to a balanced life, and nature moderates itself by watering itself down. |
"A blacksmith, Thomas Newcomen, in collaboration with a plumber, John Calley, produced the first commercially successful machine for "raising water by fire." Newcomen could not have based his design on prevailing scientific theory, White argued, because his engine relied on the dissolution of air in steam, and scientists in his day were not aware that air dissolves in water."
Clifford D. Conner, A People's History of Science (2005)
Solutions are homogeneous mixtures. The major component is called solvent, and the minor components are called solute. If both components in a solution are 50%, the term solute can be assigned to either component. When gas or solid material dissolve in a liquid, the gas or solid material is called the solute. When two liquids dissolve in each other, the major component is called the solvent and the minor component is called the solute
Many chemical reactions are carried out in solutions, and solutions are also closely related to our every day lives. The air we breathe, the liquids we drink, and the fluids in our body are all solutions. Furthermore, we are surrounded by solutions such as the air and waters (in rivers, lakes and oceans).
Types of Solutions
At the molecular level, molecules and ions of a solute are completely mixed with and interact with those of the solvent when a solute dissolves in a solvent. This type of mixing is homogeneous because no boundary is visible in the entire solution. In a mixture, differences may exist between regions or parts of the whole system.
Material exists in three states: solid, liquid, and gas. And solutions exist in all these states as well.
Gaseous mixtures are usually homogeneous and all gases mixtures are gas-gas solutions. For quantitative treatment of this type, of solutions, we will devote a unit to gases. The air is a natural gas solution, but its water and carbon dioxide contents may vary depends on the temperature and places.
When molecules of gas, solid or liquid are dispersed and mixed with those of liquid, the homogeneous (uniform) states are called liquid solutions. Solid, liquid and gas dissolve in liquid to form liquid solutions. In general, the terms solution and liquid solution are synonymous. Gases and liquid solutions have attracted the attention of most chemists, while material scientists and engineers are more interested in the manufacture and properties of solid solutions.
Many alloys, ceramics, and polymer blends are solid solutions. Within certain range, copper and zinc dissolve in each other and harden to give solid solutions called brass. Silver, gold, and copper form many different alloys with unique colors and appearances. Alloys and solid solutions are important in the world of materials. The research, development, manufacture, and production of these material are big business, and a company for example, Standard Alloys, may concentrate on some aspects of these materials.
Solubility
The maximum amount of a substance dissolved in a given volume of solvent is called solubility. Often, the solubility in water is expressed in gram/100 mL. For example, the solubilities of some common substances are given in the Table of Solubility, which is also listed in the HandbookMenu as Solubility.
A solution reached the maximum solubility is called a saturated solution. Often, another phase such as gas, liquid, or solid of the solute is present and in contact with in the solution. In general, there is no net change in the amount of solute dissolved, but the system is by no means static. In fact, the solute is constantly being dissolved and deposited at equal rate. Such a phenomenon is called equilibrium.
In case another phase is not present, a solution may be unsaturated or supersaturated. Yes, due to what can be attributed to a kinetic factor, a solution may stay supersaturated for a long time. When promoted by a seed, a solution may start to precipitate quickly. Sodium acetate has a very high solubility at say 270 K. In fact, it can dissolve in the water of crystallization similar to melting. When cooled, such a solution stay in a meta-stable state. When a seeding crystal is present or started due to surface of another medium, the entire solution will solidify. During the crystallization process, heat is evolved, and the solution becomes warm. Thus, such a solution, when properly packaged, has been used as hand warmer packs for skiers.
One useful classification of materials is polarity. Substances such as H2, O2, N2, CH4, CCl4 etc are called non-polar compounds, whereas H2O, NH3, CH3OH, NO, CO, HCl, H2S, PH3 etc are called polar compounds. Regarding solubility, a useful rule is: like dissolves like.
Polar materials dissolve polar materials whereas non-polar materials will mix and become true solutions. An additional factor to consider is the hydrogen bonding. For example, ethanol and water are completely miscible at any proportion due to the extensive hydrogen bonding among their molecules.
Electrolytes or ionic substances are soluble in water due to hydration. Due to the strong polarity of the water molecule, the positive and negative ions are pushed apart. In general, reasonable size ions are believed to have six water molecules around them, but these water molecules readily exchange with those in the medium.
There are many applications of this rule. On the small scale, personal hygiene and household cleaning requires various types of cleaning agents. As a challenge is the research and development of cleaning agents in industry, where you can find jobs or hire experts to do the R&D.
Other factor such as temperature and pressure also affects the solubility of a solvent. Thus, in specifying solubility, one should be aware of the factors.
Many chemical reactions are carried out in solutions, and solutions are also closely related to our every day lives. The air we breathe, the liquids we drink, and the fluids in our body are all solutions. Furthermore, we are surrounded by solutions such as the air and waters (in rivers, lakes and oceans).
Types of Solutions
At the molecular level, molecules and ions of a solute are completely mixed with and interact with those of the solvent when a solute dissolves in a solvent. This type of mixing is homogeneous because no boundary is visible in the entire solution. In a mixture, differences may exist between regions or parts of the whole system.
Material exists in three states: solid, liquid, and gas. And solutions exist in all these states as well.
Gaseous mixtures are usually homogeneous and all gases mixtures are gas-gas solutions. For quantitative treatment of this type, of solutions, we will devote a unit to gases. The air is a natural gas solution, but its water and carbon dioxide contents may vary depends on the temperature and places.
When molecules of gas, solid or liquid are dispersed and mixed with those of liquid, the homogeneous (uniform) states are called liquid solutions. Solid, liquid and gas dissolve in liquid to form liquid solutions. In general, the terms solution and liquid solution are synonymous. Gases and liquid solutions have attracted the attention of most chemists, while material scientists and engineers are more interested in the manufacture and properties of solid solutions.
Many alloys, ceramics, and polymer blends are solid solutions. Within certain range, copper and zinc dissolve in each other and harden to give solid solutions called brass. Silver, gold, and copper form many different alloys with unique colors and appearances. Alloys and solid solutions are important in the world of materials. The research, development, manufacture, and production of these material are big business, and a company for example, Standard Alloys, may concentrate on some aspects of these materials.
Solubility
The maximum amount of a substance dissolved in a given volume of solvent is called solubility. Often, the solubility in water is expressed in gram/100 mL. For example, the solubilities of some common substances are given in the Table of Solubility, which is also listed in the HandbookMenu as Solubility.
A solution reached the maximum solubility is called a saturated solution. Often, another phase such as gas, liquid, or solid of the solute is present and in contact with in the solution. In general, there is no net change in the amount of solute dissolved, but the system is by no means static. In fact, the solute is constantly being dissolved and deposited at equal rate. Such a phenomenon is called equilibrium.
In case another phase is not present, a solution may be unsaturated or supersaturated. Yes, due to what can be attributed to a kinetic factor, a solution may stay supersaturated for a long time. When promoted by a seed, a solution may start to precipitate quickly. Sodium acetate has a very high solubility at say 270 K. In fact, it can dissolve in the water of crystallization similar to melting. When cooled, such a solution stay in a meta-stable state. When a seeding crystal is present or started due to surface of another medium, the entire solution will solidify. During the crystallization process, heat is evolved, and the solution becomes warm. Thus, such a solution, when properly packaged, has been used as hand warmer packs for skiers.
One useful classification of materials is polarity. Substances such as H2, O2, N2, CH4, CCl4 etc are called non-polar compounds, whereas H2O, NH3, CH3OH, NO, CO, HCl, H2S, PH3 etc are called polar compounds. Regarding solubility, a useful rule is: like dissolves like.
Polar materials dissolve polar materials whereas non-polar materials will mix and become true solutions. An additional factor to consider is the hydrogen bonding. For example, ethanol and water are completely miscible at any proportion due to the extensive hydrogen bonding among their molecules.
Electrolytes or ionic substances are soluble in water due to hydration. Due to the strong polarity of the water molecule, the positive and negative ions are pushed apart. In general, reasonable size ions are believed to have six water molecules around them, but these water molecules readily exchange with those in the medium.
There are many applications of this rule. On the small scale, personal hygiene and household cleaning requires various types of cleaning agents. As a challenge is the research and development of cleaning agents in industry, where you can find jobs or hire experts to do the R&D.
Other factor such as temperature and pressure also affects the solubility of a solvent. Thus, in specifying solubility, one should be aware of the factors.
Ponder this
So solutions exists in the three main states of matter, but what about another state of matter: plasma?
Can solutions only form when a mixture is in a gaseous or liquid state? Can they be made when both the solvent and solute are in solid form?
Discuss
We now know that solutions can come in the three main states of matter: gasses, liquids, and solids. We also know that we can isolate the dissolved material easily if they are in liquid form. But what about those that are dissolved in gasses (i.e. atmospheric air) or solids (i.e. alloys)? Would it be possible to isolate the dissolved materials from these two states of matter?
