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Questions and Answers
What is the mole fraction of NaOH in a solution containing 8.00g NaOH dissolved in 90.0g of water?
What is the mole fraction of NaOH in a solution containing 8.00g NaOH dissolved in 90.0g of water?
What is the molality of a solution containing 16.5 g of naphthalene (C10H8) dissolved in 54.3g of benzene (C6H6)?
What is the molality of a solution containing 16.5 g of naphthalene (C10H8) dissolved in 54.3g of benzene (C6H6)?
What is the process by which gases take the shape of their container?
What is the process by which gases take the shape of their container?
What is the molarity of a 125 mL solution containing 0.050 moles of hydrochloric acid?
What is the molarity of a 125 mL solution containing 0.050 moles of hydrochloric acid?
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Which end of the water molecule is attracted to the chloride ion?
Which end of the water molecule is attracted to the chloride ion?
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Which of the following halogens has the weakest dispersion forces of attractions between its molecules?
Which of the following halogens has the weakest dispersion forces of attractions between its molecules?
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What is the solvent in a 70% alcohol solution?
What is the solvent in a 70% alcohol solution?
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What is the molar concentration of sucrose in a 355-mL soft drink sample containing 0.133 mol of sucrose?
What is the molar concentration of sucrose in a 355-mL soft drink sample containing 0.133 mol of sucrose?
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What is the freezing point depression of a 1.00 m aqueous solution of NaCl?
What is the freezing point depression of a 1.00 m aqueous solution of NaCl?
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What is the ideal van't Hoff factor for Ba(OH)2?
What is the ideal van't Hoff factor for Ba(OH)2?
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A solution is made by dissolving 29.25 g of an ionic substance in 1.000 kg of water. The freezing point of the solution is -1.860 oC. What is the molar mass of the ionic substance, assuming a van't Hoff factor of 2.000?
A solution is made by dissolving 29.25 g of an ionic substance in 1.000 kg of water. The freezing point of the solution is -1.860 oC. What is the molar mass of the ionic substance, assuming a van't Hoff factor of 2.000?
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What is the boiling point of a 4.00 molal solution of potassium chloride in water?
What is the boiling point of a 4.00 molal solution of potassium chloride in water?
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A 17.3 mg sample of an organic compound is ground up with 420 mg of camphor to form a homogeneous mixture melting at 170.0 oC. What is the apparent formula weight of the organic compound? (Kf of camphor = 37.7 oC/m, m.p. of camphor = 178.4 oC)
A 17.3 mg sample of an organic compound is ground up with 420 mg of camphor to form a homogeneous mixture melting at 170.0 oC. What is the apparent formula weight of the organic compound? (Kf of camphor = 37.7 oC/m, m.p. of camphor = 178.4 oC)
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Flashcards
van't Hoff factor
van't Hoff factor
The ratio of particle concentration from a solute's dissolution compared to its mass-based concentration.
Freezing point depression
Freezing point depression
The lowering of a solvent's freezing point when a solute is added, proportional to the molal concentration.
Kf of water
Kf of water
The cryoscopic constant for water, used to calculate freezing point depression, is 1.86°C/m.
Molar mass determination
Molar mass determination
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Ideal van't Hoff factors
Ideal van't Hoff factors
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Mole Fraction
Mole Fraction
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Molality
Molality
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Molarity
Molarity
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Expansion of Gases
Expansion of Gases
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Polarity
Polarity
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Sodium Hydroxide (NaOH)
Sodium Hydroxide (NaOH)
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Halogens
Halogens
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Sucrose
Sucrose
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Study Notes
Mole Fraction
- Mole fraction represents the number of molecules of a component in a mixture divided by the total number of moles in the mixture.
- It is a way to express the concentration of a solution.
- The sum of mole fractions of all components in a solution always equals one.
- Example: If 8.00 g NaOH is dissolved in 90.0 g H₂O, the mole fraction of NaOH is 0.04 and the mole fraction of H₂O is 0.96.
Molality
- Molality is a property of solutions that indicates the concentration of a solute in a solution.
- It is determined mainly by the mass of the solvent.
- Example: The molality of a solution containing 16.5 g of naphthalene (C₁₀H₈) in 54.3 g benzene (C₆H₆) is 2.38.
Gas Properties
- Gases are composed of many tiny spherical particles that are far apart compared to their size.
- Gases expand to fill the entire container they occupy.
Molarity
- Molarity is a unit of concentration expressed as the number of moles of dissolved solute per liter of solution.
- Example: The molarity of a 125 mL solution containing 0.050 moles of hydrochloric acid is 0.40 mol/L.
Water Molecules and Ions
- Water molecules are composed of two hydrogen atoms and one oxygen atom.
- The hydrogen end of a water molecule is positively charged and is attracted to negatively charged ions like chloride ions.
Halogens
- Halogens are located on the left side of the noble gases in the periodic table.
- They are five toxic, non-metallic elements that form Group 17 (VIIA) of the periodic table.
- Fluorine has the weakest dispersion forces of attraction between its molecules.
Isopropyl Alcohol
- Isopropyl alcohol is used in healthcare settings to prevent infection from needle punctures.
- The solvent in 70% alcohol solutions is alcohol.
Sucrose
- Sucrose is a disaccharide composed of glucose and fructose subunits.
- Example: A 355-mL soft drink sample containing 0.133 mol of sucrose has a molar concentration of 0.375 M.
Sodium Hydroxide
- Sodium hydroxide is used in the manufacture of soaps and detergents.
- Example: 38 mL of 0.50 mol/L NaOH contains 0.019 mol of NaOH.
Polarity and Solubility
- Polarity describes an entity with distinct opposite poles that can attract or repel each other.
- "Like dissolves like" refers to the principle that polar substances dissolve in polar solvents, and nonpolar substances dissolve in nonpolar solvents.
- Example: I₂ is more soluble in CCl₄ than in water because I₂ is nonpolar and CCl₄ is nonpolar.
Molar Mass Calculation
- The molar mass of an ionic substance can be determined using the freezing point depression of a solution of the substance in a solvent.
- Example: If 29.25 g of an ionic substance is dissolved in 1.000 kg of water and the freezing point of the solution is -1.860°C, then the molar mass of the ionic substance is 58.50 g/mol.
Freezing Point Depression and Formula Weight
- The freezing point depression of a solution depends on the concentration of solute particles.
- Example: A 17.3 mg sample of a non-electrolyte dissolved in 420 mg of camphor with a freezing point of 170.0°C has an apparent formula weight of 185 g/mol.
Sodium Chloride
- Sodium chloride is used in many applications, including de-icing roads and sidewalks.
- Using the freezing point depression constant and the concentration, the freezing point of a 1.00 m NaCl solution is -3.72°C.
Van't Hoff Factor
- The van't Hoff factor is a ratio between the calculated concentration of particles produced when a substance dissolves and the initial concentration of the substance as calculated from its mass.
- The ideal van't Hoff factors for certain compounds, like Ba(OH)₂ and K₃PO₄ are 3 and 4 respectively.
Potassium Chloride
- Potassium chloride is a medication used to treat hypokalemia.
- Example: The boiling point of a 4.00 molal KCl solution in water is 377 K.
Other Exam Topics
- Additional topics for the exam include phase changes, phase diagrams, dipole, polarity, stoichiometry, and solution chemistry.
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Description
This quiz covers essential concepts related to concentration in chemistry, including mole fraction, molality, gas properties, and molarity. It provides examples and explanations to help solidify your understanding of these topics. Test your knowledge of how these concentration measures apply in various chemical scenarios.
