Sand is insoluble in water — it does not dissolve in water, no matter how much you heat it or stir it. However, salt and sugar are soluble in water — they dissolve in water to make solutions. A solute is the substance that dissolves to make a solution.
In salt solution, salt is the solute. Since the water molecules have very strong intermolecular forces with each other and interact only weakly with carbon tetrachloride via London dispersion forces?
Let's imagine what happens when a polar solute such as sodium chloride is placed in a nonpolar solvent such as carbon tetrachloride. Because CCl 4 doesn't have a partial charge, it won't attach itself to the sodium or chloride ions. As we've mentioned before, the sodium and chloride ions in NaCl are strongly attracted to one another because of their opposite charges. This very weak solvent-solute interaction, as well as the very strong attraction between neighboring solute particles, causes sodium chloride to be insoluble in carbon tetrachloride.
If we place a nonpolar solid into a nonpolar liquid, "like dissolves like" implies that the solid will dissolve. However, the only forces that will cause the liquid to be attracted to the solid are weak London dispersion forces. Why should the solid dissolve? Let's imagine that we have placed a chunk of carbon tetrabromide in a beaker containing carbon tetrachloride.
The carbon tetrabromide molecules in the solid are held together by very weak London dispersion forces, as are the carbon tetrachloride molecules in the solvent.
One might expect, then, that there is no particular reason for the solute to dissolve. As it turns out, there's another force involved. Processes that increase the randomness of a system usually occur spontaneously we'll discuss this phenomenon, known as entropy.
Because the molecules in carbon tetrabromide will be made more random if they're mixed with another compound, the carbon tetrabromide will dissolve in the carbon tetrachloride. Electrolytes in particular promote normal rehydration to prevent fatigue during physical exertion. Are they a good choice for achieving the recommended fluid intake? Are they performance and endurance enhancers like they claim? Who should drink them? Typically, eight ounces of a sports drink provides between fifty and eighty calories and 14 to 17 grams of carbohydrate, mostly in the form of simple sugars.
Sodium and potassium are the most commonly included electrolytes in sports drinks, with the levels of these in sports drinks being highly variable. The American College of Sports Medicine says a sports drink should contain milligrams of sodium per 8 ounces as it is helpful in replenishing some of the sodium lost in sweat and promotes fluid uptake in the small intestine, improving hydration. In the summer of , the assistant football coach of the University of Florida Gators requested scientists affiliated with the university study why the withering heat of Florida caused so many heat-related illnesses in football players and provide a solution to increase athletic performance and recovery post-training or game.
University of Florida football player Chip Hinton testing Gatorade in , pictured next to the leader of its team of inventors, Robert Cade. Each particle of the solute is surrounded by particles of the solvent, carrying the solute from its original phase.
Describe what happens when an ionic solute like Na 2 SO 4 dissolves in a polar solvent. Describe what happens when a molecular solute like sucrose C 12 H 22 O 11 dissolves in a polar solvent. Classify each substance as an electrolyte or a nonelectrolyte. Each substance dissolves in H 2 O to some extent. Each ion of the ionic solute is surrounded by particles of solvent, carrying the ion from its associated crystal.
Learning Objectives To describe the dissolution process at the molecular level. The Dissolution Process What occurs at the molecular level to cause a solute to dissolve in a solvent? When a solute dissolves, the individual particles of solute become surrounded by solvent particles. As temperature increases, kinetic energy increases. The greater kinetic energy results in greater molecular motion of the gas particles.
As a result, the gas particles dissolved in the liquid are more likely to escape to the gas phase and the existing gas particles are less likely to be dissolved. The converse is true as well. The trend is thus as follows: increased temperatures mean lesser solubility and decreased temperatures mean higher solubility. Le Chatelier's principle allows better conceptualization of these trends. First, note that the process of dissolving gas in liquid is usually exothermic.
As such, increasing temperatures result in stress on the product side because heat is on the product side. In turn, Le Chatelier's principle predicts that the system shifts towards the reactant side in order to alleviate this new stress. Consequently, the equilibrium concentration of the gas particles in gaseous phase increases, resulting in lowered solubility. Conversely, decreasing temperatures result in stress on the reactant side because heat is on the product side.
In turn, Le Chatelier's principle predicts that the system shifts toward the product side in order to compensate for this new stress. Consequently, the equilibrium concentration of the gas particles in gaseous phase would decrease, resulting in greater solubility. This formula indicates that at a constant temperature when the partial pressure decreases, the concentration of gas in the liquid decreases as well, and consequently the solubility also decreases.
Conversely, when the partial pressure increases in such a situation, the concentration of gas in the liquid will increase as well; the solubility also increases. Extending the implications from Henry's law , the usefulness of Le Chatelier's principle is enhanced in predicting the effects of pressure on the solubility of gases.
Consider a system consisting of a gas that is partially dissolved in liquid. An increase in pressure would result in greater partial pressure because the gas is being further compressed. This increased partial pressure means that more gas particles will enter the liquid there is therefore less gas above the liquid, so the partial pressure decreases in order to alleviate the stress created by the increase in pressure, resulting in greater solubility.
The converse case in such a system is also true, as a decrease in pressure equates to more gas particles escaping the liquid to compensate. Bob is in the business of purifying silver compounds to extract the actual silver. He is extremely frugal. One day, he finds a barrel containing a saturated solution of silver chloride.
Which of the three should Bob add to the solution to maximize the amount of solid silver chloride minimizing the solubility of the silver chloride? Bob should add table salt to the solution. According to the common-ion effect, the additional Cl - ions would reduce the solubility of the silver chloride, which maximizes the amount of solid silver chloride.
0コメント