CP Chapter 15/16 Solutions

What Are Solutions?

What is a solution?

  • A solution is uniform ______that may contain solids, liquids, or gases.
  • Known as a ______mixture
  • Solution = ______+ ______
  • Solvent – The substance in ______abundance in the solution
  • A solvent dissolves the solute. (dissolving ______)
  • Solute – The substance dissolved in the solvent

Characteristics of Solutions

  • Soluble – The solute’s ability to ______in a solvent
  • Insoluble – The solute is ______able to dissolve in a solvent
  • Immiscible – Two liquids that can be mixed together, but ______shortly after you stop mixing them
  • Miscible – Two liquids that are ______in each other

Solvation in Aqueous Solutions

  • Solvation – The process of ______solute particles with solvent particles to form a solution
  • Aqueous solution – A solute dissolved in ______

Rules for Solvation

  • ______dissolves ______
  • Polar molecules dissolve ______molecules
  • ______molecules dissolve non-polar molecules

Factors that Affect Rate of Solvation

  • Need to increase ______between solute and solvent molecules
  1. Agitating the mixture (______)
  2. New collisions between solute and solvent will occur
  3. Increasing the surface ______of the solute (Crushing the solute)
  4. Greater surface area allows more collisions to occur
  5. Increasing the ______of the solvent
  6. Increases kinetic energy of molecules and more frequent collisions occur
  7. Increasing the ______(For gases)
  • Increases the rate of collision between particles.

Solubility

  • Solubility – The ______amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure.
  • Solubility is usually expressed in grams of solute per 100 g of solvent or in ______.
  • Saturated solution contains the ______amount of dissolved solute for a given amount of solvent at a specific pressure and temperature.
  • Unsaturated solutioncontains ______dissolved solute for a given temperature and pressure than a saturated solution
  • Supersaturated solutioncontains ______dissolved solute than a saturated solution at the same temperature

Factors That Affect Solubility

  • Temperature
  • Most substances as temperature increases solubility ______
  • ______are the exception and solubility tends to decrease as temperature increases, because they are moving quickly escaping the solvent
  • Pressure
  • The solubility of a gas in any solvent increases as the ______above the solution increases, keeping the gas from escaping in the solvent

Example 1:

If the solubility of NaCl at 25oC is 36.2 g/100 g H2O, what is the maximum mass of NaCl can be dissolved in 200.0 g of H2O at the same temperature?

Example 2:

If the solubility of KNO3 at 20oC is 79 grams in 250 grams of water, what is solubility in grams per liter?

Henry’s Law

  • Henry’s Law states that at a given temperature the solubility (S) of a gas in a liquid is directly proportional to the pressure (P)

Example 3:

The solubility of a gas is 0.35 g/L at 25.0 kPa of pressure. What is the solubility when the pressure is increased to 115 kPa?

Electrolytes

  • Electrolytes are compounds that ______or ionize in water to form a solution that conducts an electric current
  • Ionic compounds are ______because they dissociate into ions
  • Ex: NaCl(s) Na+ + Cl–
  • Electrolytes dissociate into individual ions and conduct an ______current

Strong and Weak Electrolytes

  • A strong electrolyte conducts a ______current and the compound has completely dissociated into ions
  • NaCl
  • A weak electrolyte conducts a ______current because only part of the solute exists as ions.
  • NH3 (Ammonia)
  • A nonelectrolytedoes ______dissociate or form ions, thus does not conduct a current.
  • Most molecular compounds are nonelectrolytes
  • Sucrose (sugar)

Solution Concentrations

Percent by mass

Example 1:An aquarium must contain 13.6 g NaCl per 100.0 g of water. What is the percent by mass (m/m) of NaCl in the solution?

Example 2:You have a 650.0 g of a KCl solution. If the percent by mass of the solute, KCl is 1.25% (m/m), how many grams of solute are in the solution? How many grams of solvent are in the solution?

Percent by volume

Example 3:What is the percent by volume (v/v) of ethanol in a solution that contains 45 ml of ethanol dissolved in 145 ml of water?

Example 4:If you have 200.0 mL of a 35.0% aqueous solution of ethanol, what volume of ethanol and water are in the solution?

Parts Per Million (ppm)

Example 5:If 25 grams of a chemical is dissolved in 75 grams of water, what is the concentration of the chemical in parts per million (ppm).

Example 6:Suppose 17 grams of sucrose is dissolved in 183 grams of water. What is the concentration of sucrose in ppm?

Example 7:150mL of an aqueous sodium chloride solution contains 0.0045g NaCl.Calculate the concentration of NaCl in parts per million (ppm).1 ppm = 1 mg/L

Example 8:Convert 0.0035% NaCl by mass into parts per million of NaCl.

Molarity

Example 1:Calculate the molarity of 1.75 L solution containing 3.45 moles of CaCl2.

Example 2:Calculate the molarity of an 855 mL solution containing 2.75 moles of NaNO3.

Example 3:A 0.1005 L of IV solution contains 5.10 g of glucose. What is the molarity of this solution? The molar mass of glucose is 180.18 g/mol.

Example 4:How many moles of HCl are in a 0.85 L of a 0.50 M solution?

Example 5:How many moles of NaNO3 are in 655 mL of a 3.45 M solution?

Preparing Molar Solutions

Example 1:How many grams of CaCl2 would be dissolved in a 2.5L of a 0.10 M solution of CaCl2?

Example 2:How many grams of NaOH are in 2.5 L of 4.0 M NaOH solution?

Example 3:How many grams of NaOH are in 350 mL of a 2.3 M solution?

Diluting Solutions

Example 1:What volume, in milliliter of 2.00M CaCl2 stock solution would you use to make 0.50L of 0.300 M calcium chloride solution?

What volume in milliliters of a 12.0 M HCl solution would you use to make 2.50 L of a 2.00 M HCl solution?

Colligative Properties

  • The physical properties of solutions that are different than the physical properties of a pure solvent. These depend only upon the number of particles in a solution.
  • Vapor pressure lowering
  • Boiling point increasing
  • Freezing point lowering
  • Put in order from least to greatest colligative properties. Then explain.

Ex 1: H2O (l) → H2O (l)

Ex 2: NaCl(s) → Na+(aq) + Cl- (aq) (2 moles of ions)

Ex 3: C6H12O6 (s) → C6H12O6 (aq) (1 mole)

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