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Questions and Answers
Classify each process as an endothermic or exothermic process.
Classify each process as an endothermic or exothermic process.
- Forming solute-solvent attractions (correct)
- Breaking solute-solute attractions (correct)
- Breaking solvent-solvent attractions (correct)
- All of the above
Determine the enthalpy of solution for a solid with H values for breaking attractions that are one third of the magnitude compared to forming attractions.
Determine the enthalpy of solution for a solid with H values for breaking attractions that are one third of the magnitude compared to forming attractions.
Exothermic
Determine the enthalpy of solution for a solid with H values for breaking attractions that are three times the magnitude compared to forming attractions.
Determine the enthalpy of solution for a solid with H values for breaking attractions that are three times the magnitude compared to forming attractions.
Endothermic
Rank the following substances in order from most soluble to least soluble in water: ethane (C2H6), 1-butanol (C4H9OH), table salt (NaCl), propane (C3H8).
Rank the following substances in order from most soluble to least soluble in water: ethane (C2H6), 1-butanol (C4H9OH), table salt (NaCl), propane (C3H8).
Which solvent will best dissolve wax, a complex mixture mostly made up of CH3-CH2-CH2-CH2-CH2-?
Which solvent will best dissolve wax, a complex mixture mostly made up of CH3-CH2-CH2-CH2-CH2-?
If you double the partial pressure of a gas over a liquid at constant temperature, there are twice as many gas molecules in the liquid.
If you double the partial pressure of a gas over a liquid at constant temperature, there are twice as many gas molecules in the liquid.
Where would you expect N2 to fit in a given gas solubility graph compared to CO?
Where would you expect N2 to fit in a given gas solubility graph compared to CO?
Calculate the molality of a 2.350*10^-2 M NaCl solution in water, using 999.4 mL of water.
Calculate the molality of a 2.350*10^-2 M NaCl solution in water, using 999.4 mL of water.
Calculate the mole fraction of a 2.350*10^-2 M NaCl solution in water.
Calculate the mole fraction of a 2.350*10^-2 M NaCl solution in water.
Calculate the concentration of the salt solution in percent by mass for a 2.350*10^-2 M NaCl solution.
Calculate the concentration of the salt solution in percent by mass for a 2.350*10^-2 M NaCl solution.
Calculate the concentration of the salt solution in parts per million for a 2.350*10^-2 M NaCl solution.
Calculate the concentration of the salt solution in parts per million for a 2.350*10^-2 M NaCl solution.
If more solvent is added to a solution, doubling the original mass of solvent and then adding more solute to double the original mass of solute, what happens to the molality of the final solution compared to the original molality?
If more solvent is added to a solution, doubling the original mass of solvent and then adding more solute to double the original mass of solute, what happens to the molality of the final solution compared to the original molality?
What is the concentration in units of mole fraction for the solubility of oxygen gas in water at 40 C, which is 1.0 mmol/L?
What is the concentration in units of mole fraction for the solubility of oxygen gas in water at 40 C, which is 1.0 mmol/L?
Calculate the molarity of calcium in maple syrup if the density is 1.325 g/mL and 100.00 g of syrup contains 67 mg of calcium.
Calculate the molarity of calcium in maple syrup if the density is 1.325 g/mL and 100.00 g of syrup contains 67 mg of calcium.
What is the molarity of commercial concentrated aqueous ammonia, which is 28% NH3 by mass and has a density of 0.90 g/mL?
What is the molarity of commercial concentrated aqueous ammonia, which is 28% NH3 by mass and has a density of 0.90 g/mL?
Arrange the solutions with freezing points: A) -1.45 C, B) -5.96 C, C) -3.04 C.
Arrange the solutions with freezing points: A) -1.45 C, B) -5.96 C, C) -3.04 C.
What is the molal concentration of glucose in a solution that freezes at -3.15 C?
What is the molal concentration of glucose in a solution that freezes at -3.15 C?
What is the molal concentration of glucose in a solution that boils at 102.06 C?
What is the molal concentration of glucose in a solution that boils at 102.06 C?
Increasing the temperature raises the osmotic pressure of a solution.
Increasing the temperature raises the osmotic pressure of a solution.
Which aqueous solution will have the lowest freezing point?
Which aqueous solution will have the lowest freezing point?
List the following aqueous solutions in order of decreasing freezing point: 0.40 m glycerin (C3H8O3), 0.020 m potassium bromide (KBr), 0.030 m phenol (C6H5OH).
List the following aqueous solutions in order of decreasing freezing point: 0.40 m glycerin (C3H8O3), 0.020 m potassium bromide (KBr), 0.030 m phenol (C6H5OH).
Define molality.
Define molality.
The density of the solution is needed to calculate the molarity of a 17.5% (by mass) aqueous solution of nitric acid.
The density of the solution is needed to calculate the molarity of a 17.5% (by mass) aqueous solution of nitric acid.
What is the concentration of Cl- in a solution prepared by dissolving 23.7 g of CaCl2 in 375 g of water, where the density is 1.05 g/mL?
What is the concentration of Cl- in a solution prepared by dissolving 23.7 g of CaCl2 in 375 g of water, where the density is 1.05 g/mL?
What is the percent by mass of urea in a solution prepared by dissolving 16 g of urea in 52 g of H2O?
What is the percent by mass of urea in a solution prepared by dissolving 16 g of urea in 52 g of H2O?
What is the mole fraction of urea in a solution prepared by dissolving 16 g of urea in 39 g H2O?
What is the mole fraction of urea in a solution prepared by dissolving 16 g of urea in 39 g H2O?
Identify the type of interactions involved in each of the following processes taking place during the dissolution of sodium chloride (NaCl) in water.
Identify the type of interactions involved in each of the following processes taking place during the dissolution of sodium chloride (NaCl) in water.
Which substances are most likely to undergo dissolution in water?
Which substances are most likely to undergo dissolution in water?
Classify the given compounds according to their strongest solute-solvent interaction when dissolving in water.
Classify the given compounds according to their strongest solute-solvent interaction when dissolving in water.
Which substance is the most soluble in CCl4?
Which substance is the most soluble in CCl4?
What does the phrase 'like dissolves like' refer to?
What does the phrase 'like dissolves like' refer to?
When solutions of strong electrolytes in water are formed, the ions are surrounded by water molecules. This interaction is known as what?
When solutions of strong electrolytes in water are formed, the ions are surrounded by water molecules. This interaction is known as what?
Which substance is most likely to dissolve in CCl4?
Which substance is most likely to dissolve in CCl4?
Which of the following liquids is NOT miscible with water?
Which of the following liquids is NOT miscible with water?
If the methane contained in a saturated solution at 25 C was extracted and placed under STP conditions, what volume would it occupy?
If the methane contained in a saturated solution at 25 C was extracted and placed under STP conditions, what volume would it occupy?
What explains the variations in solubility for methane, ethane, and ethylene?
What explains the variations in solubility for methane, ethane, and ethylene?
Compared to nitrogen, what makes ethylene more soluble in water?
Compared to nitrogen, what makes ethylene more soluble in water?
Why is nitric oxide more soluble than nitrogen and oxygen?
Why is nitric oxide more soluble than nitrogen and oxygen?
What makes nitrogen less soluble compared to oxygen?
What makes nitrogen less soluble compared to oxygen?
Explain the high solubility of sulfur dioxide.
Explain the high solubility of sulfur dioxide.
Study Notes
Types of Processes
- Exothermic processes involve forming solute-solvent attractions.
- Endothermic processes involve breaking solute-solute and solvent-solvent attractions.
Enthalpy of Solution
- An exothermic reaction occurs when the breaking of attractions is one-third the magnitude of the forming attractions.
- An endothermic reaction occurs when the breaking of attractions is three times the magnitude of the forming attractions, or when all steps involved have approximately equal magnitudes.
Solubility Rankings
- Substances ranked from most to least soluble in water: NaCl (table salt), 1-butanol (C4H9OH), propane (C3H8), and ethane (C2H6).
Solvent Compatibility
- Pentane (CH3CH2CH2CH2CH3) is best for dissolving wax, which is primarily composed of long-chain hydrocarbons.
Gas Solubility and Pressure
- Doubling the partial pressure of a gas above a liquid does not mean there are twice as many gas molecules in the liquid.
Estimated Graph Placement
- N2 is expected to fit just below CO on a solubility graph.
Concentration Calculations
- A 2.350 x 10^-2 M NaCl solution corresponds to a molality of 2.356 x 10^-2 m.
- The mole fraction of NaCl in the solution is 4.241 x 10^-4, and its mass percent is 0.1375%.
- The parts per million (ppm) concentration of the NaCl solution is 1375 ppm.
Effects on Molality
- Doubling the solvent mass and solute mass keeps the molality of the final solution unchanged.
Concentration Conversion
- The solubility of oxygen gas in water at 40°C is equivalent to a mole fraction of 1.80 x 10^-5.
Calcium Molarity and Concentration
- Molarity of Ca2+ ions in maple syrup is 0.022 M.
- Commercial concentrated ammonia has a molarity of 15 M due to its 28% mass concentration.
Freezing Point Depression
- The order of decreasing molal concentration related to freezing points: B (-5.96°C), C (-3.04°C), A (-1.45°C).
- For a glucose solution that freezes at -3.15°C, the molal concentration is 1.69 molal.
Boiling Point Elevation
- A glucose solution that boils at 102.06°C has a molal concentration of 4.02 molal.
Osmotic Pressure
- Increasing the temperature of a solution raises its osmotic pressure.
Freezing Point Comparison
- The lowest freezing point among solutions is 0.15 m NaCl.
Solution Freezing Points
- Aqueous solutions arranged from highest to lowest freezing point: 0.030 m phenol, 0.020 m potassium bromide, 0.40 m glycerin.
Molality Definition
- Molality is defined as moles of solute per kilogram of solvent.
Density and Molarity Calculations
- To calculate molarity of a 17.5% nitric acid solution, density information is essential.
- The concentration of Cl- in a solution with calcium chloride is computed as 1.12 M.
Percent by Mass and Mole Fraction
- The percent by mass of urea in solution is calculated at 24%.
- The mole fraction of urea, after dissolution of 16 g in 39 g of H2O, is 0.11.
Dissolution Interactions
- Solvent-solvent interactions are characterized by dipole-dipole attractions between water molecules.
- Solute-solute interactions involve ion-ion attractions between sodium chloride ions.
- Solvent-solute interactions occur between sodium ions and water's oxygen atoms, and between chloride ions and water's hydrogen atoms.
Solubility Prediction
- Lithium bromide, sodium iodine, and potassium bromide are likely to dissolve in water.
Solute-Solvent Interactions
- Dipole-dipole forces are strongest in ethanol (C2H5OH) and HF.
- Ion-dipole forces are observed in salts like CaCl2 and CuSO4.
Solubility in Nonpolar Solvents
- C4H10 is most soluble in CCl4.
- "Like dissolves like" principle applies where polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.
Hydration Process
- The interaction of ions from strong electrolytes in water is known as hydration.
Miscibility
- Hexane (C6H14) is not miscible with water.
Gas Solubility Variations
- Variations in solubility of methane, ethane, and ethylene arise from differences in bonding and molecular size.
Comparative Solubility
- Ethylene's larger size enhances its water solubility over nitrogen due to increased polarity.
Reactivity with Water
- Sulfur dioxide's high solubility arises from its ability to react with water.
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Description
Test your understanding of solutions with this quiz on endothermic and exothermic processes outlined in Chapter 13. Classify processes based on interactions in solutions and calculate the enthalpy of solutions using provided H values. Prepare to deepen your chemistry knowledge!
