Exothermic Reaction Lab
GOMEZ, Gina Melissa N. SY1213
Solvation also sometimes called dissolution, is the process of attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a solvent they spread out and become surrounded by solvent molecules.
Example:
As an ionic compound dissolves, such as NaCl, the ions become surrounded by the solvent, say H2O(water) molecules. The ions are said to be 'solvated' as they become surrounded by the solvent, similar to a hoard of bees surrounding a nest. The solvation process helps stabilize the ions in solution and prevents cations and anions from recombining. Furthermore, because the ions and their shells of surrounding water molecules are free to move about, the …show more content…
ions become dispersed uniformly throughout the solution.
Factors that Affect Solubility
Solute-Solvent Relations
The relation between the solute and solvent is very important in determining solubility. Strong solute-solvent attractions equate to greater solubility while weak solute-solvent attractions equate to lesser solubility. In turn, Polar solutes tend to dissolve best in polar solvents while non-polar solutes tend to dissolve best in non-polar solvents. In the case of a polar solute and non-polar solvent (or vice versa), it tends to be insoluble or only soluble to a miniscule degree. The general rule to remember is "Like Dissolves Like".
Common-Ion Effect
The common-ion effect is a term that describes the decrease in solubility of an ionic compound when a salt that contains an ion that already exists in the chemical equilibrium is added to the mixture. This effect best be explained by Le Chatelier's Principle. Imagine if we were add the slightly soluble ionic compound Calcium Sulfate into water. The net ionic equation for the resulting chemical equilibrium would be:
Calcium Sulfate is slightly soluble meaning that at equilibrium, most of the calcium and sulfate exists in the solid form of Calcium Sulfate. Let's say that we now add the soluble ionic compound Copper Sulfate ( ) into the solution. Copper Sulfate is soluble, therefore its only important effect on the net ionic equation is the addition of more Sulfate ions.
The Sulfate ions dissociated from Copper Sulfate are already present (common to) in the mixture from the slight dissociation of Calcium Sulfate. Thus, this addition of Sulfate ions places stress on the previously established equilibrium. Le Châtelier's Principle dictates that the additional stress on this product side of the equilibrium results in the shift of equilibrium towards the reactants side in order to alleviate this new stress. In shifting towards the reactant side, we can see that from the above equation that the solubility of the slightly soluble Calcium Sulfate is reduced even further. Temperature
Temperature changes affect the solubility of Solids, Liquids and Gases differently. However, those effects have only finitely determined for Solids and Gases.
Solids
The effects of temperature on the solubility of solids differ depending on whether the reaction is endothermic or exothermic.
Using Le Chatelier's Principle, we can determine the effects of temperature in both scenarios.
First, imagine an endothermic reaction (heat is on the reactants side where the solid is). Increasing the temperature would result in stress on the reactants side from the additional heat. Le Châtelier's Principle predicts that the system would shift towards the product's side in order to alleviate this stress. By shifting towards the product's side, more of the solid is dissociated when equilibrium is again established - which equates to increased solubility.
Second, imagine an exothermic reaction (heat is on the products side where the dissociated ions from the solid are). Increasing the temperature would result in stress on the products side from the additional heat. Le Châtelier's Principle predicts that the system would shift towards the reactant's side in order to alleviate this stress. By shifting towards the reactant's side, less of the solid is dissociated when equilibrium is again established - which equates to decreased …show more content…
solubility.
Liquids
In the case of liquids, there is no defined trends for the effects of temperature on the solubility of liquids. As such, you will probably never encounter liquid-liquid solute-solvent mixtures in problems.
Gases
In understanding the effects of temperature on the solubility of gases, it is first important to remember that temperature is the measure of the average kinetic energy. 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. So, the trend now appears as follows : increased temperatures mean lesser solubility and decreased temperatures mean higher solubility.
Using Le Chatelier's Principle, we can better conceptualize these trends. First, note that the process of dissolving gas in liquid is usually exothermic. As such, increasing temperatures would result in stress on the product's side (since heat is on the product's side). In turn, Le Chatelier's Principle predicts that the system will shift towards the reactant's side in order to alleviate this new stress. Consequently, the equilibrium concentration of the gas particles in gaseous phase would increase - which equates to lowered solubility.
Conversely, decreasing temperatures would result in stress on the reactant's side (since heat is on the product's side). In turn, Le Châtelier's Principle predicts that the system will shift towards the product's side in order to compensate for this new stress. Consequently, the equilibrium concentration of the gas particles in gaseous phase would decrease - which equates to greaters olubility.
Pressure
The effects of pressure are only significant in affecting the solubility of gases in liquids.
Solids & Liquids
The effects of pressure changes on the solubility of solids and liquids are negligible.
Gases
The effects of pressure on the solubility of gases in liquids can best be described through a combination of Henry's Law and Le Chatelier's Principle. Henry's Law dictates that when temperature is constant, the solubility of the gas corresponds to it's partial pressure. Consider the following formula of Henry's Law: where p is the partial pressure of the gas above the liquid, is Henry's Law constant, and c is the concentrate of the gas in the liquid.
From this formula, you can see that (at a constant temperature) when the partial pressure decreases, the concentration of gas in the liquid will decrease as well - which means that solubility also decreases.
Conversely, when the partial pressure increases in such a situation, the concentration of gas in the liquid will increase as well - which means that solubility also increases. Extending the implications from Henry's Law, we can now enhance our understanding of Le Châtelier's Principle in predicting the effects of pressure on the solubility of gases. Le Chatelier's Principle dictates that a system will shift in such a way as to alleviate stress.
Consider a system consisting of a gas that is partially dissolved in liquid. An increase in pressure would result in greater partial pressure (since the gas is being further compressed). This increased partial pressure means that more gas particles will enter the liquid (which means less gas above the liquid, so partial pressure decreases) in order to alleviate the stress created by the increase in pressure - which equates to 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.
SOLUBILITY | | "The solubility of a solute in a solvent at a particular temperature is the number of grams of the solute necessary to saturate 100gm of the solvent at that temperature." | FACTORS AFFECTING SOLUBILITY | | There are three main factors that control solubility of a solute. (1) Temperature (2) Nature of solute or solvent (3) Pressure | EFFECT OF TEMPERATURE | | Generally in many cases solubility increases with the rise in temperature and decreases with the fall of temperature but it is not necessary in all cases. However we must follow two behaviors: | In endothermic process solubility increases with the increase in temperature and vice versa. | For example:solubility of potassium nitrate increases with the increase in temperature. | In exothermic process solubility decrease with the increase in temperature. | For example:solubility of calcium oxide decreases with the increase in temperature. | Gases are more soluble in cold solvent than in hot solvent. | NATURE OF SOLUTE AND SOLVENT | | Solubility of a solute in a solvent purely depends on the nature of both solute and solvent. A polar solute dissolved in polar solvent. Solubility of a non-polar solute in a solvent is large. A polar solute has low solubility or insoluble in a non-polar solvent. | EFFECT OF PRESSURE | | The effect of pressure is observed only in the case of gases. An increase in pressure increases of solubility of a gas in a liquid. For example carbon di oxide is filled in cold drink bottles (such as coca cola, Pepsi 7up etc.)under pressure. |
Solvation also sometimes called dissolution, is the process of attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a solvent they spread out and become surrounded by solvent molecules.
Example:
As an ionic compound dissolves, such as NaCl, the ions become surrounded by the solvent, say H2O(water) molecules. The ions are said to be 'solvated' as they become surrounded by the solvent, similar to a hoard of bees surrounding a nest. The solvation process helps stabilize the ions in solution and prevents cations and anions from recombining. Furthermore, because the ions and their shells of surrounding water molecules are free to move about, the …show more content…
ions become dispersed uniformly throughout the solution.
Factors that Affect Solubility
Solute-Solvent Relations
The relation between the solute and solvent is very important in determining solubility. Strong solute-solvent attractions equate to greater solubility while weak solute-solvent attractions equate to lesser solubility. In turn, Polar solutes tend to dissolve best in polar solvents while non-polar solutes tend to dissolve best in non-polar solvents. In the case of a polar solute and non-polar solvent (or vice versa), it tends to be insoluble or only soluble to a miniscule degree. The general rule to remember is "Like Dissolves Like".
Common-Ion Effect
The common-ion effect is a term that describes the decrease in solubility of an ionic compound when a salt that contains an ion that already exists in the chemical equilibrium is added to the mixture. This effect best be explained by Le Chatelier's Principle. Imagine if we were add the slightly soluble ionic compound Calcium Sulfate into water. The net ionic equation for the resulting chemical equilibrium would be:
Calcium Sulfate is slightly soluble meaning that at equilibrium, most of the calcium and sulfate exists in the solid form of Calcium Sulfate. Let's say that we now add the soluble ionic compound Copper Sulfate ( ) into the solution. Copper Sulfate is soluble, therefore its only important effect on the net ionic equation is the addition of more Sulfate ions.
The Sulfate ions dissociated from Copper Sulfate are already present (common to) in the mixture from the slight dissociation of Calcium Sulfate. Thus, this addition of Sulfate ions places stress on the previously established equilibrium. Le Châtelier's Principle dictates that the additional stress on this product side of the equilibrium results in the shift of equilibrium towards the reactants side in order to alleviate this new stress. In shifting towards the reactant side, we can see that from the above equation that the solubility of the slightly soluble Calcium Sulfate is reduced even further. Temperature
Temperature changes affect the solubility of Solids, Liquids and Gases differently. However, those effects have only finitely determined for Solids and Gases.
Solids
The effects of temperature on the solubility of solids differ depending on whether the reaction is endothermic or exothermic.
Using Le Chatelier's Principle, we can determine the effects of temperature in both scenarios.
First, imagine an endothermic reaction (heat is on the reactants side where the solid is). Increasing the temperature would result in stress on the reactants side from the additional heat. Le Châtelier's Principle predicts that the system would shift towards the product's side in order to alleviate this stress. By shifting towards the product's side, more of the solid is dissociated when equilibrium is again established - which equates to increased solubility.
Second, imagine an exothermic reaction (heat is on the products side where the dissociated ions from the solid are). Increasing the temperature would result in stress on the products side from the additional heat. Le Châtelier's Principle predicts that the system would shift towards the reactant's side in order to alleviate this stress. By shifting towards the reactant's side, less of the solid is dissociated when equilibrium is again established - which equates to decreased …show more content…
solubility.
Liquids
In the case of liquids, there is no defined trends for the effects of temperature on the solubility of liquids. As such, you will probably never encounter liquid-liquid solute-solvent mixtures in problems.
Gases
In understanding the effects of temperature on the solubility of gases, it is first important to remember that temperature is the measure of the average kinetic energy. 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. So, the trend now appears as follows : increased temperatures mean lesser solubility and decreased temperatures mean higher solubility.
Using Le Chatelier's Principle, we can better conceptualize these trends. First, note that the process of dissolving gas in liquid is usually exothermic. As such, increasing temperatures would result in stress on the product's side (since heat is on the product's side). In turn, Le Chatelier's Principle predicts that the system will shift towards the reactant's side in order to alleviate this new stress. Consequently, the equilibrium concentration of the gas particles in gaseous phase would increase - which equates to lowered solubility.
Conversely, decreasing temperatures would result in stress on the reactant's side (since heat is on the product's side). In turn, Le Châtelier's Principle predicts that the system will shift towards the product's side in order to compensate for this new stress. Consequently, the equilibrium concentration of the gas particles in gaseous phase would decrease - which equates to greaters olubility.
Pressure
The effects of pressure are only significant in affecting the solubility of gases in liquids.
Solids & Liquids
The effects of pressure changes on the solubility of solids and liquids are negligible.
Gases
The effects of pressure on the solubility of gases in liquids can best be described through a combination of Henry's Law and Le Chatelier's Principle. Henry's Law dictates that when temperature is constant, the solubility of the gas corresponds to it's partial pressure. Consider the following formula of Henry's Law: where p is the partial pressure of the gas above the liquid, is Henry's Law constant, and c is the concentrate of the gas in the liquid.
From this formula, you can see that (at a constant temperature) when the partial pressure decreases, the concentration of gas in the liquid will decrease as well - which means that solubility also decreases.
Conversely, when the partial pressure increases in such a situation, the concentration of gas in the liquid will increase as well - which means that solubility also increases. Extending the implications from Henry's Law, we can now enhance our understanding of Le Châtelier's Principle in predicting the effects of pressure on the solubility of gases. Le Chatelier's Principle dictates that a system will shift in such a way as to alleviate stress.
Consider a system consisting of a gas that is partially dissolved in liquid. An increase in pressure would result in greater partial pressure (since the gas is being further compressed). This increased partial pressure means that more gas particles will enter the liquid (which means less gas above the liquid, so partial pressure decreases) in order to alleviate the stress created by the increase in pressure - which equates to 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.
SOLUBILITY | | "The solubility of a solute in a solvent at a particular temperature is the number of grams of the solute necessary to saturate 100gm of the solvent at that temperature." | FACTORS AFFECTING SOLUBILITY | | There are three main factors that control solubility of a solute. (1) Temperature (2) Nature of solute or solvent (3) Pressure | EFFECT OF TEMPERATURE | | Generally in many cases solubility increases with the rise in temperature and decreases with the fall of temperature but it is not necessary in all cases. However we must follow two behaviors: | In endothermic process solubility increases with the increase in temperature and vice versa. | For example:solubility of potassium nitrate increases with the increase in temperature. | In exothermic process solubility decrease with the increase in temperature. | For example:solubility of calcium oxide decreases with the increase in temperature. | Gases are more soluble in cold solvent than in hot solvent. | NATURE OF SOLUTE AND SOLVENT | | Solubility of a solute in a solvent purely depends on the nature of both solute and solvent. A polar solute dissolved in polar solvent. Solubility of a non-polar solute in a solvent is large. A polar solute has low solubility or insoluble in a non-polar solvent. | EFFECT OF PRESSURE | | The effect of pressure is observed only in the case of gases. An increase in pressure increases of solubility of a gas in a liquid. For example carbon di oxide is filled in cold drink bottles (such as coca cola, Pepsi 7up etc.)under pressure. |