Chem 107 Exam 3 Study Guide
Chem 107 Exam 3 Study Guide Chem 107
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This 8 page Study Guide was uploaded by Kelly Johnson on Monday March 28, 2016. The Study Guide belongs to Chem 107 at West Chester University of Pennsylvania taught by Jacqueline Butler in Winter 2016. Since its upload, it has received 82 views. For similar materials see General Chemistry for Health Science in Chemistry at West Chester University of Pennsylvania.
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Date Created: 03/28/16
Study Guide for Chapters 5 and 6 1. Chapter 5 a. Gas Laws i. Kinetic Molecular Theory 1. All mater is composed of small particles called atoms 2. Atoms are in constant motion unless at absolute zero (0K) 3. The amount of motion is proportional to the temperature. a. With increased temperature, comes increased movement 4. The three states of matter (solid, liquid, gas) differ in the amount of motion in which their particles have, as well as the extent with which they interact a. Solid very little movement, collide often b. Liquid expand to fill container, but still remain in contact c. Gas expand to fill the space, but separate. Most of the area a gas takes up is filled with air and not that gas’ particles. ii. Pressure and Force 1. Pressure is defined as the force over and area iii. Conditions of STP 1. 0° C 2. 1 ATM (atmospheric pressure) a. 1 atm=760 mmHg=760 torr=101.325 kPa (given on test) 3. 1 mol/ 22.4 L iv. Absolute temperature 1. Absolute zero is 0 K or 273 °C 2. K= C + 273 v. Gas Law Equation 1. Describes the relationship between pressure, volume, and temperature as long as the number of particles is constant P1V 1 = P 2V 2 2. T 1 T 2 3. Can be rearranged to solve for any of the variables vi. Dalton’s Law of Partial Pressures 1. The sum of partial pressures of the component gases is equal to the total pressure of the mixture 2. P Total 1+P 2P 3 vii. Avogadro’s Law 1. If temperature and pressure are constant, the number of particles can be calculated in relation to the volume 2. A specific volume of any gas has the same number of particles V 1 = V 2 3. N 1 N 2 viii. Ideal Gas Law 1. Represents the relationship between volume, pressure, temperature, and number of moles in a gas 2. PV=nRT ix. Density 1. Expressed in grams per liters Molar Mass 2. D= 22.4L x. Ideal vs. Real Gases 1. Ideal gases do not really exist, but nonpolar gases are the closest 2. Expected to have no attraction between molecules, molecules take up no space, & at high temp/low pressure they will act less like ideal gases b. Liquids and Solids i. Liquid State 1. Incompressible 2. Viscosity a. Resistance to flow dependent on intermolecular forces i. To flow, bonds must break b. More forces= harder to flow c. Decreases with an increased temperature 3. Surface tension a. Attractive forces help form a skin along the top of a liquid b. Net forces pull down c. Surfactant decreases surface tension 4. Vapor Pressure a. Defined as the number of molecules that can enter into the atmosphere at equilibrium b. Requires energy to break free, and lose energy to return c. Kinetic theory i. Liquid molecules are in constant motion, with their average kinetic energy directly proportional to the kelvin temperature ii. As temperature increases, so does temperature d. Dynamic equilibrium means that the rate of condensation equals the rate of evaporation i. Evaporation liquid to gas ii. Condensation gas to liquid 5. Boiling Point a. Boiling point is the point at which vapor pressure equals atmospheric pressure b. Depends on intermolecular forces i. Stronger forces= higher boiling point 6. Forces a. Van der Waals i. London Dispersion Forces 1. In all molecules 2. Only force in nonpolar molecules 3. Simplest attraction ii. DipoleDipole 1. Only occurs in polar molecules 2. Orient so opposite charges are close together b. Hydrogen Bonding i. NOT A VAN DER WAALS FORCE ii. Very strong iii. Hydrogen bonded directly to oxygen, nitrogen, and fluorine ii. The Solid State 1. Properties a. Highly organized b. Fixed shape and volume c. Incompressible d. Melting point depends on strength of the attractive forces e. Crystalline Has a regular and repeating structure i. Ionic 1. Strong electrostatic forces hold them together 2. Extremely high melting and boiling points 3. Hard and brittle properties 4. Dissolves in water (electrolytic) ii. Covalent 1. Held together only by covalent bonds 2. High melting and boiling points 3. Extremely hard 4. Bond in a network iii. Molecular 1. Held together by intermolecular forces 2. Often soft 3. Have a low melting point 4. Often volatile iv. Metallic 1. Metal held together with metal bonds, not covalent bonds 2. Metal Bonds a. Overlapping orbitals b. This causes high electron density where electrons are extremely mobile. c. Allow for conductivity 3. Valence electrons are delocalized, meaning they are located around the outside (“sea of electrons”) f. Amorphous g. Sublimation i. The process in which a liquid converts directly to a gas, without stopping in the liquid phase ii. Ex. Dry ice iii. Properties of Solutions 1. Definition a. The components of a mixture are uniformly intermingled, making it homogeneous b. Can be liquids, solids, or gases 2. Terms a. Solution homogeneous mixture b. Solute substance in lesser quantity c. Solvent substance in higher quantity d. Aqueous Solution solution in which the solvent is water 3. When a Solute Dissolves a. There are attractive forces between solute particles holding them together. There are also attractive forces between solvents. b. Once combined, forces form between the solute and solvent. If this force is strong enough, the solute will dissolve c. Factors affect solubility i. “Like dissolves like” There must be similar forces in both the solute and the solvent for the substances to be able to dissolve 4. General Properties of Liquid Solutions a. Clear, transparent, with no visible particles b. May have color c. Electrolytes are formed from solutes that are soluble ionic compounds, and nonelectrolytes do no dissociate d. Volumes of solute and solvent are not additive iv. Colloids 1. Colloidal Suspensions a. Suspended particles that are unevenly distributed in a medium b. Particles are slightly larger so they can be seen when a light is shown through, but not to the naked eye i. If particles are smaller than 1 nm, it is a solution ii. If particles are between 1 nm and 1000 nm, it is a colloid iii. If particles are larger than 1000 nm, it is a precipitate 2. Tyndall Effect a. The ability of a colloidal suspension to scatter light v. Degree of Solubility 1. Solubility describes how much of a particular solute can dissolve in a certain solvent at a specific temperature vi. Factors that Affect 1. Polarity of a solvent and solute (forces involved) a. The more polar, the lower the solubility 2. Temperature a. Increase in temperature leads to increase in solubility 3. Pressure a. Very little effect if any vii. Levels of Saturation 1. Saturated a. The solution contains as much solute that can be dissolved at a certain temperature 2. Unsaturated a. More solute can be added at that temperature 3. Supersaturated a. Solvent holds more solute than is normally possible at that temperature b. Must be heated, solute added, and then cooled slowly viii. Solubility and Equilibrium 1. If excess solute is added, some dissolves 2. Rate of dissolution is faster at first. Precipitation occurs quickly later on 3. Saturated Solution is at dynamic equilibrium a. Rate of dissolution is equal the rate of precipitation ix. Henry’s Law 1. The number of moles of a gas dissolved in a liquid at a given temperature is proportional to the partial pressure of the gas above the liquid 2. Gases are more soluble at low temperatures and it greatly decreases at higher temperatures x. Solution Composition 1. Mass/Volume percent mL of solution x100 ¿ a. massof solute(g) ¿ 2. Mass/mass percent massof solute(g) a. x100 massof solution(g) 3. Parts per thousand (ppt) massof solute(g) x1,000 a. massof solution(g) 4. Parts per million (ppm) massof solute(g) a. x1,000,000 massof solution(g) *** iii and iv are often used for very dilute substances c. Concentration in Molarity (M) i. Molarity is the number of moles of solute in one liter of solution amountof solute(mol) ii. Molarity(M)= volumeof solution(L) iii. Dilution of Solutions M1V 1=M2V 2 1. a. M= molarity b. V= Volume iv. Molality 1. Molality is described as the moles of solute per kg of solvent d. Concentration Dependent Solution Properties i. Colligative Properties 1. Dependent on the concentration of the solute particles 2. Include: a. Vapor pressure lowering i. Raoult’s Law 1. When solute is added, vapor pressure decreases in proportion to the concentration b. Boiling point elevation i. If a solute is present, boiling point must be raised in order to raise the vapor pressure to atmospheric temp ii. Proportional to the number of solute particles 1. An electrolyte will have a higher effect than a nonelectrolyte iii. ΔT= K mb solute 1. K =bMolal boiling point elevation constant 2. m= molality of a solute 3. i= van’t Hoff factor (moles of particles) c. Freezing point depression i. Solute molecules interfere with the rate at which liquid water molecules associate to form the solid state ii. Proportional to the number of solute particles iii. ΔT= Km f solute 1. K folal freezing point depression constant 2. m= molality of the solute 3. i= van’t Hoff Factor (moles of particles) d. Osmotic pressure i. Some membranes have small pores that allow particles to pass through them based on size ii. Semipermeable membranes allow solvent but not solute to diffuse from one side to another iii. Osmosis is defined as the passage of solvent from a dilute solution to a more concentrated solution 1. Pressure is required to stop this flow iv. Is the solutions on both sides of the membrane are the same, the solutions are known as isotonic e. Tonicity and the Cell i. Crenation 1. When a cell is placed in a solution that has a higher solute concentration (hypertonic) than the cell itself, water will rush out of the cell causing the cell to collapse. This is known as crenation 2. Pickling a cucumber uses this process ii. Hemolysis 1. When the cell is placed in a solution of lower concentration (hypotonic) than the cell itself, water will rush into the cell causing it to burst/lyse iii. Isotonic 1. When the cell is place in a solution of its same concentration, there will be equal flow between sides and the cell is happy f. Aqueous Solutions i. Water is known as the “universal solvent” and is an excellent solvent for polar molecules. Water is also the most abundant liquid on earth. (60% of the human body is water) g. Biological Effects of Electrolytes in Solution i. Cations 1. Na and K are the two most important cations 2. They move across the cell membrane via active transport 3. If Na is too high or too low, the body reacts a. Low: Decreased urine output, dry mouth, flushed skin, fever b. High: confusion, stupor, coma 4. If K is too high or too low, it often results in death by heart failure ii. Anions 1. Cl helps maintain acid/base balance, osmotic pressure, and Oxygen transport by hemoglobin 2. HCO is3the form in which most CO2 exits the body iii. Proteins 1. Act as blood clotting factors, antibodies, and albumins 2. Transported as a colloidal suspension 3. Transport nutrients and waste products 4.
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