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104 Cards in this Set
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Homogeneous mixtures, are also known as ___________. __________ are mixtures in which atoms, ions, and molecules intermingle on the molecular and atomic scale. |
Homogeneous mixtures, are also known as solutions. Solutions are mixtures in which atoms, ions, and molecules intermingle on the molecular and atomic scale. |
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*A homogeneous mixture of two or more substances or components. |
Solution |
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*The major component in a solution. |
Solvent |
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*The minority component in a solution. |
Solute |
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*What are aqueous solutions? |
Solutions in which water is the solvent and a solid, liquid, or gas is the solute. |
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A solution may be composed of a _______ and a ________ but it may also be composed of a _____ and a _________, two different ________, or other combinations. |
A solution may be composed of a solid and a liquid but it may also be composed of a gas and a liquid, two different liquids, or other combinations. |
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*The amount of the substance that will dissolve in a given amount of solvent. |
The solubility of a substance. |
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The solubility of one substance in another depends on what? |
On nature's tendency toward mixing and on the types of intermolecular forces. |
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*A measure of energy randomization or energy dispersal in a system. |
Entropy |
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T/F The formation of a solution does not necessarily lower the potential energy of its constituent particles. T/F We cannot think of the mixing of two ideal gases as lowering their potential energy. The tendency to mix is related to a concept called what? |
True True Entropy |
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T/F Energy tends to disperse. T/F Energy spontaneously concentrates itself. The pervasive tendency for energy to spread out, or disperse, whenever it is not restrained from doing so is the reason that... |
True False. Energy does not spontaneously concentrate itself. ... two ideal gases mix. |
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Which has greater entropy (or greater energy dispersal): neon gas in a one liter container or neon gas in a two liter container? |
Neon gas in a two liter container. |
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T/F In the absence of intermolecular forces, two substances spontaneously mix to form a homogeneous solution. |
True |
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T/F Intermolecular forces and the structures that result from them, may promote the formation of a solution or prevent it, depending on the nature of the forces in the particular combination of solute and solvent. |
True |
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The interactions between a solvent particle and a solute particle. The interactions between a solvent particle and another solvent particle. The interactions between a solute particle and another solute particle. |
Solvent-Solute Interactions Solvent-Solvent Interactions Solute-Solute Interactions |
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A solution generally forms if the solvent-solute interactions are _______________ to, or ___________ than, the solvent-solvent interactions and solute-solute interactions. |
A solution generally forms if the solvent-solute interactions are comparable to, or stronger than, the solvent-solvent interactions and solute-solute interactions. |
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*The ability of two or more substances to be soluble in each other in all proportions. |
Miscible |
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The formation of the solution is driven by... |
...the tendency toward mixing or toward greater entropy. |
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*In general, we can use the rule of thumb that _____ _________ _____ when predicting the formation of solutions. Similar kinds of __________ dissolve similar kinds of _________. |
In general, we can use the rule of thumb that like dissolves like when predicting the formation of solutions. Similar kinds of solvents dissolve similar kinds of solutes. |
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If solvent-solute interactions are _________ than solvent-solvent and solute-solute interactions -- in other words, if solvent molecules and solute molecules each interact more __________ with molecules of their own kind than with molecules of the other kind -- then a solution may still form, depending on the relative disparities between the interactions. If the disparity is ________, the tendency to mix results in the formation of a solution even though the process is energetically uphill. If the disparity is ________, however, a solution does not form. |
If solvent-solute interactions are weaker than solvent-solvent and solute-solute interactions -- in other words, if solvent molecules and solute molecules each interact more strongly with molecules of their own kind than with molecules of the other kind -- then a solution may still form, depending on the relative disparities between the interactions. If the disparity is small, the tendency to mix results in the formation of a solution even though the process is energetically uphill. If the disparity is large, however, a solution does not form. |
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*What are the three steps in solution formation? |
1) Separating the solute into its constituent particles. 2) Separating the solvent particles from each other to make room for the solute particles. 3) Mixing the solute particles with the solvent particles. |
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*With the three steps in solution formation, which steps are endothermic and which steps are exothermic? |
Step one is endothermic. (Breaking intermolecular forces) Step two is endothermic. (Breaking intermolecular forces) Step three is exothermic. (Formation of intermolecular forces) |
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The sum of a system's internal energy. Positive Delta H Negative Delta H |
Enthalpy Endothermic Exothermic |
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*The overall enthalpy change upon solution formation is the sum of the changes in enthalpy for all three steps, which is called what? |
Enthalpy of solution (Delta H soln) |
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With the three steps of solution formation, the first two terms are endothermic and the third term is exothermic, so the overall sign of the enthalpy of solution (DELTA_H_soln) depends on what? |
On the magnitudes of the individual terms. |
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What does this symbol stand for? |
Enthalpy of Solution |
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If the sum of the endothermic terms is approximately equal in magnitude to the exothermic term, what is the enthalpy of solution? |
About zero. The increasing entropy upon mixing drives the formation of a solution, while the overall energy of the system remains nearly constant. |
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If the sum of the endothermic terms is smaller in magnitude than the exothermic term, what is the enthalpy of solution? |
It is negative and the solution process is exothermic. Both the tendency toward lower energy and the tendency toward greater entropy drive the formation of a solution. |
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If the sum of the endothermic terms is greater in magnitude than the exothermic term, what is the enthalpy of solution? |
It is positive and the solution process is endothermic. As long as the enthalpy of solution is not too large, the tendency toward greater entropy still drives the formation of a solution. If, on the other hand, the enthalpy of solution is too large, a solution does not form. |
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When the process of solution formation is endothermic, does the solution always form? |
No, only if the enthalpy of solution is not too large. |
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What is Enthalpy? |
(H) The sum of the internal energy of a system and the product of its pressure and volume. |
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What is Entropy? |
(S) A measure of the energy randomization or energy dispersal in a system. |
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With the three steps of solution formation, which step is the enthalpy of mixing? |
The third step, where the solutes and solvents mix. |
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For aqueous solutions, we combine the enthalpy of the solvent and the enthalpy of mixing into a single term called what? |
The Heat of Hydration |
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What is this symbol? |
The Heat of Hydration |
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What is the enthalpy change that occurs when 1 mol of the gaseous solute ions is dissolved in water called? |
The Heat of Hydration |
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T/F The heat of hydration is always largely negative (exothermic) for ionic compounds. |
True |
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Because the ion-dipole interactions that occur between a dissolved ion and the surrounding water molecules are much ____________ than the hydrogen bonds in water, the heat of hydration is always largely __________ (____________) for ionic compounds. |
Because the ion-dipole interactions that occur between a dissolved ion and the surrounding water molecules are much stronger than the hydrogen bonds in water, the heat of hydration is always largely negative (exothermic) for ionic compounds. |
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For ionic compounds, the enthalpy of the solute, the energy required to separate the solute into its constituent particles, is what? |
It is the negative of the solute's lattice energy. |
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With the formation of an aqueous solution containing ionic compounds, is the enthalpy of the solute endothermic or exothermic? With the formation of an aqueous solution containing ionic compounds, is the heat of hydration endothermic or exothermic? |
Endothermic Exothermic |
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For ionic aqueous solutions, the overall enthalpy of solution depends on the relative magnitudes of the ___________ ___ ____ ________ and the ______ ___ ___________, with ________ possible scenarios. What are they? |
For ionic aqueous solutions, the overall enthalpy of solution depends on the relative magnitudes of the enthalpy of the solute and the heat of hydration, with three possible scenarios. |
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For ionic aqueous solutions, the overall enthalpy of solution depends on the relative magnitudes of the enthalpy of the solute and the heat of hydration, with three possible scenarios. What are they? |
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What does it mean when the absolute value of the heat of hydration is greater than the enthalpy of the solute? |
The enthalpy of solution is negative and the solution process is exothermic. |
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What does it mean when the absolute value of the heat of hydration is less than the enthalpy of the solute? |
The enthalpy of solution is positive and the solution process is endothermic (if a solution forms at all). |
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What does it mean when the absolute value of the heat of hydration is about the same as the enthalpy of the solute? |
The enthalpy of solution is approximately zero and the solution process is neither substantially exothermic nor substantially endothermic. |
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What is another name for solvation? |
Dissolution |
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The dissolution of a solvent is an ______________ process similar to the _____________ process associated with a state change. |
The dissolution of a solvent is an equilibrium process similar to the equilibrium process associated with a state change. |
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The rate of dissolution far exceeds the rate of __________________, but as the concentration of dissolved sodium chloride increases, the rate of __________________ also increases. Eventually the rates of dissolution and __________________ become equal - dynamic equilibrium has been reached. |
The rate of dissolution far exceeds the rate of recrystallization, but as the concentration of dissolved sodium chloride increases, the rate of recrystallization also increases. Eventually the rates of dissolution and recrystallization become equal - dynamic equilibrium has been reached. |
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A solution in which the dissolved solute is in dynamic equilibrium with the solid (undissolved) solute is called what? What happens if we add additional solute it this? |
A saturated solution The solute will not dissolve. |
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A solution containing less than the equilibrium amount of solute is called what? What happens if we add additional solute it this? |
An unsaturated solution The solute will dissolve. |
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A solution containing more than the equilibrium amount of the solute sometimes forms and is called what? T/F They are unstable and the excess solute normally precipitates out of the solution. |
A supersaturated solution True |
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T/F The solubility of solids in water can be highly dependent on temperature. Although exceptions exist, the solubility of most solids in water increases with increasing what? |
True Temperature |
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This is a common way to purify a solid. T/F The solubility of a gas in a liquid is affected by only temperature. |
Recrystallization False. The solubility of a gas in a liquid is affected by both temperature and pressure. |
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T/F The solubility of gas and temperature are an inverse relationship. The solubility of gases in liquids _________ with _____________ temperature. T/F The higher the pressure of a gas above a liquid, the more stable the gas is in the liquid. |
True The solubility of gases in liquids decreases with increasing temperature. True |
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What is this? |
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What can we do with Henry's law? T/F Henry's law equation shows that the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid. |
Quantify the solubility of gases with increasing pressure. True |
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This type of solution contains small quantities of solute relative to the amount of solvent. This type of solution contains large quantities of solute relative to the amount of solvent. |
Dilute Solution Concentrated Solution |
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What are the six ways talked of in the book for representing solution concentration? |
Molarity Molality Mole Fraction Mole Percent Parts by Mass Parts by Volume |
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What are the three subways for conveying parts by mass and parts by volume? |
Percent by ________ Parts per Million by _________ Parts per Billion by _________ |
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What do we do when making a solution of a specified molarity? Molarity depends on what, and because of this molarity varies with what? When is molality really useful? |
We put the solute into a flask and then add water or another solvent to the desired volume of solution. Molarity depends on volume, and because of this molarity varies with temperature? When we need to compare concentrations over a range of different temperatures. |
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T/F Near 25ºC, ppm = mg solute / L solution We especially use parts per volume for what? |
True Solutions where the solute and the solvent are both liquids. |
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Can these both be true? |
Yes |
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How do we express mole fraction? Whats another equation to express mole percent? |
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T/F Salt lowers the temperature at which a saltwater solution freezes. |
True |
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What is the name of the property that depends on the number of particles dissolved in solution and not on the type of particle? |
Colligative property |
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What are the four colligative properties examined? |
Vapor pressure lowering Freezing point depression Boiling point elevation Osmotic pressure |
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Because these properties depend on the __________ of dissolved particles, nonelectrolytes are treated slightly differently than electrolytes when determining colligative properties. When 1 mol of a nonelectrolyte dissolves in water, it forms ___ mol of dissolved particles. When 1 mol of an electrolyte dissolves in water, it forms _____ _____ ___ mol of dissolved particles. The colligative properties of electrolyte solutions reflect this ________ concentration of dissolved particles. |
Because these properties depend on the number of dissolved particles, nonelectrolytes are treated slightly differently than electrolytes when determining colligative properties. When 1 mol of a nonelectrolyte dissolves in water, it forms 1 mol of dissolved particles. When 1 mol of an electrolyte dissolves in water, it forms more than 1 mol of dissolved particles. The colligative properties of electrolyte solutions reflect this higher concentration of dissolved particles. |
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What is the vapor pressure of a liquid? T/F Nature has a tendency to mix. |
The pressure of the gas above the liquid when the two are in dynamic equilibrium. True |
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What is the effect of a nonvolatile nonelectrolyte solute on the vapor pressure of the liquid into which it dissolves? T/F The vapor pressure of the solution is directly proportional to the amount of the solvent in the solution. |
The vapor pressure of the solution is lower than the vapor pressure of the pure solvent. True |
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Why is the vapor pressure of a solution lower than that of the pure solvent? Dissociate into ions and conduct electricity. Do not dissociate into ions and do not conduct electricity. |
Because of nature's tendency toward mixing (toward greater entropy). Electrolytes Nonelectrolytes |
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Which has a lower vapor pressure? Which has a higher vapor pressure? |
The cup on the left has the higher vapor pressure. The cup on the right has the lower vapor pressure. |
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What is this? |
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Can a solute be volatile? T/F Solutions can be ideal and nonideal. T/F Vapor pressure lowering occurs at all temperatures. |
Yes True True |
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What is an ideal solution? What is a non ideal solution? T/F In an ideal solution, the solute-solvent interactions are similar in magnitude to the solute-solute and solvent-solvent interactions. |
The solution's behavior follows Raoult's law at all concentrations for both the solvent and the solute. The solution's behavior doesn't follow Raoult's law at all concentrations for both the solvent and the solute. True |
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What is this and what is it for? |
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What is this equation? |
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What is this equation? |
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T/F The freezing point of a solution containing a nonvolatile solute is lower than the freezing point of the pure solvent. T/F The boiling point of a solution containing a nonvolatile solute is lower than the boiling point of the pure solvent. What is the Kf for water? What is the Kb for water? |
True False. The boiling point of a solution containing a nonvolatile solute is higher than the boiling point of the pure solvent. Kf = 1.86ºC/m Kb = 0.512ºC/m |
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This is the flow of solvent from a solution of lower solute concentration to one of higher solute concentration . |
Osmosis |
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Why do concentrated solutions draw solvent from more dilute solutions? This is a membrane that selectively allows some substances to pass through but not others. |
Because of nature's tendency to mix. Semipermeable Membrane |
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Can osmosis be opposed or stopped by external pressure? If osmosis can be stopped, what would that pressure be called? |
Yes, osmosis can be opposed and even stopped. The pressure required to stop osmotic flow is called osmotic pressure. |
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What is this? |
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What is this? |
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What does "i" stand for? |
van't Hoff Factor |
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What is the van't Hoff Factor? |
The ratio of moles of particles in solution to moles of formula units dissolved. |
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The freezing point depression of a 1 mol sodium chloride solution is nearly twice as large as a 1 mol sucrose solution. Why is this? |
Because sodium chloride dissociates into nearly 2 mol of ions in solution. |
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For 1 mol of NaCl can we expect the van't Hoff factor to be exactly two? Why does this happen? |
No. It approaches the expected value but doesn't reach it. Because some ions effectively pair in solution. Dissociation of ions is not complete. |
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What is the formula for freezing point depression for ionic solutions? What is the formula for boiling point elevation for ionic solutions? What is the formula for osmotic pressure for ionic solutions? |
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T/F Just as the freezing point depression of a solution containing an electrolyte solute is greater than that of a solution containing the same concentrations of a nonelectrolyte solute, so the vapor pressure lowering is greater (for the same reasons). T/F To calculate the vapor pressure of a solution containing an ionic solute, we need to account for the dissociation of the solute when we calculate the mole fraction of the solvent. |
True True |
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IV Solutions that must have osmotic pressures equal to those of body fluids are called what? IV Solutions that have osmotic pressures greater than those of body fluids are called what? IV Solutions that have osmotic pressures less than those of body fluids are called what? |
Isomotic or isotonic Hyperosmotic Hyposmotic |
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What do hyperosmotic solutions do to tissues and cells? What do hyposmotic solutions do to tissues and cells? |
They take water out of them, so that they shrivel. They pump water into them, so that they burst. |
