Solutions

• What is a solution in chemistry?

  A homogeneous mixture of solute and solvent
• What are the states in which a solution can exist?

  It can be liquid, solid, or gaseous
• How is the composition of a solution characterized?

  Its composition is even throughout the mixture
• What is solvation?

  The process of mixing the solute and the solvent
• What factors can affect the solvation process?

  It can be favored or not, and can be exothermic or endothermic
• What determines whether the solvation process is exothermic or endothermic?

  The stability of the water and salt alone versus the stability of the solvated salt
• What two main aspects should be considered when drawing the solvation of a salt?

  Orientation of water and size of ions
• What is the formula for molarity?

  Molarity = moles of solute / volume of solution
• What is the unit for molarity?

  mol/L or M
• What is the principle behind solubility in terms of intermolecular attraction?

  Substances with similar intermolecular attraction will dissolve in one another
• How do ionic compounds behave in polar solvents?

  Cations interact with the negative side and anions with the positive side of the solvent
• How do polar molecules behave in polar solvents?

  They align their dipole moments
• Which substance will be least soluble in water?


  anything nonpolar
• What is chromatography used for in separation techniques?

  • Involves interaction/affinity between substances
  • Two phases: mobile phase and stationary phase
  • Moderately polar stationary phase
• How does distillation work as a separation technique?

  • Based on different boiling points
  • Utilizes vapor pressure differences of substances
• What is microwave radiation associated with in molecular transitions?


  Transitions in molecular rotational levels
• What does spectroscopy study in relation to matter?

  It studies how matter absorbs and emits radiation in different regions of the spectra

  
• What is infrared radiation associated with in molecular transitions?


  Transitions in molecular vibrational levels
• How does the energy requirement differ between vibrational and rotational states of bonds?

  Vibrational states require more energy than rotational states
• How does the energy of a photon relate to its frequency?

  The energy of the photon is related to the frequency of the radiation
• What is the equation relating the speed of light, wavelength, and frequency?

  c = λν
• What is the equation relating the energy of a photon to its frequency?

  E = hν
• What is the Beer-Lambert law used for?

  • Relates absorption of light to three variables:
  • A = abc
  • a = molar absorptivity
  • b = path length of light
  • c = concentration of the solution
• What is a spectrophotometer used for?

  To determine the absorption of a chemical substance

  
• What are the practice problems related to molarity and solutions?

  1. Calculate molarity after dilution
  2. Determine mass needed for a specific molarity
  3. Find molarities of ions in mixed solutions
• factors affecting solubility Solids:

  • Temperature: high solubility at high temperature
  • Stirring: increases solubility
  • Surface area: increases solubility
• Solute GAS

  Temperature = low

  Stirring = low

  Pressure = high
• Solute SOLID

  Temperature   = high (WS solubility curve)

  Stirring = high

  Pressure = N/A

  Surface area = high
• Solubility Curve

  • on line - saturated
  • above line - supersaturated
  • below line - unsaturated
• Solution Preparation

  1. find mass
  2. insert solid in _(#volume) volumetric flask
  3. add water and stir to dissolve - not till line yet
  4. fill water till line
• What is a solution?

  A homogeneous mixture of two or more substances
• What are the components of a solution?

  The solute is the minor component, and the solvent is the major component
• What does "like dissolves like" mean in terms of solubility?

  Polar solvents dissolve polar or ionic solutes, while nonpolar solvents dissolve nonpolar solutes
• Which solvent would you use to dissolve salt?

  Water, as it is a polar solvent
• What happens during the solvation process of salt in water?

  Ionic bonds break, and ions are surrounded by solvent molecules
• What type of interactions occur between solute and solvent molecules?

  Dipole interactions occur between solute and solvent molecules
• What are the enthalpy changes during the solvation process?

  Energy is absorbed to break solute and solvent bonds but released when new bonds form
• What are the solubility rules for ionic compounds?

  • Group 1 and ammonium salts are soluble
  • Nitrates, acetates, and perchlorates are soluble
  • Chlorides, bromides, and iodides are soluble except with Ag⁺, Pb²⁺, and Hg₂²⁺
  • Sulfates are soluble except with Ba²⁺, Sr²⁺, Pb²⁺, or Ca²⁺
• What is the definition of molarity (M)?

  Moles of solute per liter of solution
• How do you calculate the total ions from a dissociated ionic compound like NaCl?

  Calculate moles of dissociated ions, Na⁺ and Cl⁻