Final Exam Study guide PDF

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Final Exam Study Guide

1. Know how to draw Lewis structures a. Key Steps: i. Count valence electrons ii. make structure with single bonds iii. add lone pairs iv. If more electrons are needed, form double or triple bonds v. Calculate formal charge, ensure it is as low as possible b. Be able to determine the best resonance structures from a series of options a. Calcualte formal charge (#valence electrons – dots – dashes) b. smaller formal charges is better c. formal charges should go on more electronegative atom if possible

2. Know how to determine molecular geometry and electron geometry (memorize these)

3. Know how to determine if a molecule is polar Polarity requires: a. asymmetry b. a polar bond Remember that polar bonds require an electronegativity difference > 0.4. Electronegativity chart will be given. Also remember that lone pairs or different terminal atoms break symmetry. (Exception: Linear and square planar geometries). 4. Intermolecular forces a. Know how to identify the four intermolecular forces (IMF) i. London Dispersion – all molecules have this ii. Dipole-Dipole forces – polar molecules have this (know how to determine if a molecule is polar!) iii. Hydrogen bonds – molecules with H bonded to O, N or have this iv. Ion-Dipole forces – occurs in mixtures of ionic compounds and polar compounds b. Be able to rank molecules by intermolecular forces.

i. H-bonding > dipole > dispersion ii. Molar mass breaks ties c. Know how intermolecular forces relate to properties of compounds i. Viscosity – resistance to flow – increases with stronger IMF ii. Surface tension – energy needed to deform liquid – increases with stronger IMF iii. Boiling Point – temperature at which a substances boils – increases with stronger IMF iv. Melting Point – temperature at which a substance melts – increases with stronger IMF v. Rate of Evaporation – how quickly a substance evaporates – increases with weaker IMF vi. Adhesion – the attraction between a molecule and a surface – (don’t need to rank strength) vii. Cohesion – The attraction between two molecules in a liquid – (don’t need to rank strength) viii. Capillary action – liquid sucked up a tube due to adhesive forces – (don’t need to rank strength) 5. Kinetics a. Different types of rates i. Initial rate = speed at start of reaction ii. Average rate = the average rate over a period of time iii. Instantaneous rate = that rate at a specific time during a reaction b. Differential Rate Laws (i.e. R = k[A]a[B]b…) i. Be able to determine rate order from a table of trials (i.e. the method of initial rates) ii. Be able to determine rate order with respect to each reactant or overall iii. Be able to determine the units for K. Here is a helpful table: Overal Rate Order Units for K 0 M/s 1 1/s 2 1/s × M 3 1/s × M2 4 1/s × M3 5 1/s × M4 *Notice each additional rate order divides the units of k by another factor of M iv. Be able to calculate the rate of a reaction from concentrations and k c. Activation Energy and the Arrhenius equation i. Know how catalysts affect rates 1. They lower activation energy and increase rate ii. Know how temperature affects rates 1. Higher temperature gives faster rates iii. Know how to interpret Arrhenius plots

d. Integrated rate laws i. Be able to identify 0th, 1st and 2nd order integrated rate laws ii. Be able to use these rate laws to calculate changes in concentrations iii. Be able to calculate half-life for 0th, 1st, and 2nd order reactions e. Useful video on integrated rate laws: https://www.youtube.com/watch?v=2LMdj91x2HA 7. Chemical equilibrium a. Know the definition of dynamic equilibrium i. Dynamic equilibrium – a reaction which has an equal rate in the forward and reverse direction so no products are being made. b. Understand the meaning of different sizes of equilibrium constants i. K < 1 -> reactants are favored ii. K = 1 -> reactants and products are in balance iii. K > 1 -> products are favored c. ICE table calculations i. Be able to solve for final concentrations for a reaction given an equilibrium constant d. Understand what factors impact the equilibrium constant i. Pressure and temperature e. ICE table problem: https://www.youtube.com/watch?v=aJ0KNQ5-KaI f. Be able to calculate K from equilibrium concentrations ( No ice table needed) g. Be able to use le chatlier’s principle to determine how a reaction shifts (towards products or reactants). https://www.youtube.com/watch?v=PciV_Wuh9V8 8. Ksp and Molar solubility a. Be able to calculate molar solubility or Ksp for a dissolution reaction b. Be able to determine if something will dissolve based on Ksp. i. Calculate Q and compare it to Ksp. If Q > Ksp, it wont dissolve, if Q< Ksp it will dissolve. c. Understand the factors which impact solubility i. Common ion effect ii. pH d. Ksp video: https://www.youtube.com/watch?v=T2GGlNKa3YQ&t=31s 9. Acid/Base Equilibrium and pH a. Know how to calculate the pH, pOH, [OH-] and [H3O+] for a solution when given one of these variables.. b. Know the definition of Bronsted-Lowry Acids/bases and conjugate acids bases i. Bronsted-Lowry Acid = anything which donates H+ ii. Bronsted-Lowry Base = anything which accepts H+ iii. Conjugate acid = the product which gained the H+ iv. Conjugate base = the product which lost an H+ c. Be able to calculate the pH of a weak acid or base using an ICE table d. Using pH equations: https://www.youtube.com/watch?v=89_5W9p-NnY&t=555s e. Weak acid pH; https://www.youtube.com/watch?v=OE4-yfON0Zw f. Be able to determine if a salt is acidic basic or netural

10. Titrations a. Know the pH at equivalence for different types of titrations Titration type pH at Equivalence Strong Acid/Strong 7 (neutral) Base Weak Acid/ Strong >7 (basic) Base Weak Base/ Strong Henderson-Hasselbalch, Buffer Broken? -> pH equations 12. Thermodynamics a. Be able to determine changes in entropy from examining an equation i. Increases in moles of gas from reactants to products increases entropy b. Be familiar with the first two laws of the of thermodynamics i. 1st Law: Energy is conserved or ΔE = q + w ii. 2nd Law: The entropy of the universe constantly increases, or for spontaneous processes the entropy of the universe increases c. Be able to calculate entropy, gibbs free energy, or enthalpy from a table of thermodynamic data d. Be able to calculate gibbs free energy from entropy, temperature, and enthalpy

e. Be able to know if a re

13. Electrochemistry a. Be able to balance electrochemical reactions in acidic, basic and neutral conditions b. Know the sign on the terminals in a voltaic cell, the reaction that happens there (oxidation or reduction) and the name (cathode or anode)

Intro to redox: https://www.youtube.com/watch?v=5rtJdjas-mY Acidic reactions: https://www.youtube.com/watch?v=IZ1tKxsqV74 Basic ractions: https://www.youtube.com/watch?v=v5sDNmYCaqo...