StudentLecture_04

StudentLecture_04 - Announcements 1/24/2010 Lab this week:...

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Announcements 1/24/2010 Lab this week: A Chemical Oscillation Reaction. HW04 released which means HW03 is due on Friday Exam 1, 8:00 PM, Monday, February 7. Covers Lectures 1 – 7, HW 1- 4, Labs from weeks 1 - 3
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Lab: Chemical Oscillation Reaction Review units of concentration: Molarity (M) Molality ( m ) Percent by mass Mole Fraction (X) Parts per million (ppm) Lab Assignments: Chapter 3 in the Lab Manual Textbook sections 4.5 and 14.1 Prelab is calculation of how to prepare the solutions needed from the reagents provided
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Example : How would you prepare 50.0 mL of a 0.0200 M solution of Na 2 CO 3 from the solid? 2 3 2 3 2 3 2 3 0.0200 mol Na CO 105.99 g Na CO 50.0 mL x x = 0.106 g Na CO 1000 mL 1 mol Na CO Step 2: Using an analytical balance, weigh 0.106 g Na 2 CO 3 . Step 3: Dissolve Na 2 CO 3 in DI water in a 50.0 mL volumetric flask. Dilute to the line with DI water. Moles in 50 mL (V x M) Moles to grams Step 1: Determine the mass of Na 2 CO 3 needed
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The Rate of a Reaction Change in concentration Rate Change in time Square brackets indicate molar concentration [HCl] = 0.10 M means “the molar concentration of HCl is 0.10 moles per liter”. - (conc A 2 - conc A 1 ) t 2 - t 1 conc Rate [ ]/ t = time
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The Rate of a Reaction The rate of a reaction usually _________ _________________ as the reaction proceeds! ______________ : Total change in conc. over a period of time _____________________ : Rate at a particular instant in time _____________ : Instantaneous rate when reactants are mixed To measure initial rate: Determine slope of line __________________ to the curve of [A] vs t at t = 0 Why initial rate?
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Average Rate of a Reaction [A] vs time for the reaction A B Average rate over 8 s conc Rate = - time Rate = - 0.06 - 0.40 Rate = - 8 - 0 Rate = ______________ Note: Rates are always positive, by convention Average rate = slope of _________________
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StudentLecture_04 - Announcements 1/24/2010 Lab this week:...

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