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Lab Exam Review

Lab Exam Review. What To Expect. Time Allotted: 75 minutes Stations: 4 (15 min/station) 1 Lab Component for each unit Out of: 40 (10 marks/station) 10% of Final Grade You are allowed to bring your lab book into the exam as a resource.

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Lab Exam Review

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  1. Lab Exam Review

  2. What To Expect • Time Allotted: 75 minutes • Stations: 4 (15 min/station) • 1 Lab Component for each unit • Out of: 40 (10 marks/station) • 10% of Final Grade • You are allowed to bring your lab book into the exam as a resource. • You will require a pencil, eraser, ruler, and calculator

  3. What To Expect • Station 1: Determining the Ka of a weak acid • Station 2: Reactions of alcohols • Station 3: Determining molar enthalpy • Station 4: Identifying the type of an unknown solid

  4. Pay Close Attention • As I work through each demo it is your responsibility to note any key procedures or calculations required to complete the lab. You will not be receiving a summary handout.

  5. Station 1 • Purpose: to determine the ionization constant Ka for a weak acid • Materials Provided: • Burette • Retort Stand • Burette clip • 10 mL volumetric pipette • 250 mL Erlenmeyer flask • phenolphthalein indicator • Sodium hydroxide solution (concentration will be given) • Weak Acid (concentration unknown) • The pH of the unknown acid. • You will be required to write a procedure, record observations, and complete the analysis questions required to determine the Ka pH of Acetic Acid used in demo = 2.34

  6. Station 1 • Sample Ka: Acetic Acid • CH3COOH CH3COO- + H3O+ • pH = -log[H3O+] Therefore [H3O+]= 10-pH • This calculation will require an ICF and ICE table!!

  7. Station 2 • Purpose: to identify an alcohol as either a primary, secondary, or tertiary alcohol • Materials Provided: • 2 unknown alcohols (alcohol a and b) • Test tube rack • 5 - 10 mL graduated pipettes • 4 test tubes • 4 rubber stoppers • HCl solution • KMnO 4 solution • You will be required to write a procedure and record observations. Based on your observations you will determine the types of alcohols reacted

  8. Station 2 • Primary alcohols react quickly with KMnO4 • Two step oxidation to carboxylic acids • Secondary alcohols react slowly with KMnO4 • One step oxidation to ketone • Tertiary alcohols do not react with KMnO4 • Cannot undergo oxidation • Primary alcohols do not react with HCl • Separate into two insoluble layers • Secondary alcohols react slowly with HCl • One layer with cloudy precipitate that slowly disappears • Tertiary alcohols react very quickly with HCl • One layer with cloudy precipitate that disappears very quickly

  9. Station 3 • Purpose: To determine the molar enthalpy of solution for a given ionic solid. • Materials Provided: • Coffee cup calorimeter • Thermometer • 100 mL graduated cylinder • Electronic balance • A given ionic solid • Deionized water • You will be required to write a procedure, record observations, and complete the analysis questions required to determine the molar enthalpy of the given ionic solid

  10. Station 3 • Q = mc∆t • m = mass, c = specific heat capacity, ∆t = change in temperature • Specific heat capacity of water = 4.19 J/goC • Density of water = 1.0 g/mL • ∆H = -Q • ∆H = n∆Hsol

  11. Station 4 • Purpose: To classify an unknown substance as a molecular solid, ionic solid, network covalent solid, or metallic solid • Materials Provided: • Unknown Solid • 100 mL beaker • Deionized water • Conductivity meter • Mortar and pestle • Crucible • hotplate • You will be required to write a procedure and record observations. Based on your observations you will determine the type of solid

  12. Station 4

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