lecture 5

lecture 5 - CHEM 6BL Experiment 5: Qualitative Analysis...

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Unformatted text preview: CHEM 6BL Experiment 5: Qualitative Analysis Instructor: Dr. Sandrine Berniolles Page 1 1 Chemistry 6BL Lab/Course Schedule Chemistry 6BL Lab/Course Schedule---------- Prelab Expt. 5 Lab Holiday Mon/Tues End Expt. 4C/Expt. 5 (Parts I-II, Group A) 1 st lab 2 nd lab Qual. Analysis (Expt. 5)------------ Nov. 10 Prelab & Report Due Dates Lab Schedule Lab Period Lecture & Exam Schedule Date 2 Experiment #5 Experiment #5 : Qualitative Analysis : Qualitative Analysis z Experiment Concepts: Solubility & K sp s Le Chateliers Principle (H 2 S 2 H + + S 2- ) Redox Reactions (in acid or base ) More Inorganic Complex Chemistry You will use these concepts to identify metal ions in an unknown ion solution 3 Qualitative Analysis Qualitative Analysis z Similar to Gravimetric Analysis ( Expt #1 ) in that precipitation is involved z But Gravimetric Analysis is quantitative z You will use your knowledge of precipitation and K sp values to identify various metal ions qualitatively qualitatively CHEM 6BL Experiment 5: Qualitative Analysis Instructor: Dr. Sandrine Berniolles Page 2 4 Qualitative Analysis: ID'ing Ions Qualitative Analysis: ID'ing Ions z In this experiment, you will investigate a mixture of ten common metal ions: Ag + , Hg + (i.e. Hg 2 2+ ) Cu 2+ , Mn 2+ , Zn 2+ , Ni 2+ Bi 3+ , Fe 3+ , Cr 3+ {Sn 4+ } 5 Anions and Salt Solubilities Anions and Salt Solubilities Anion Soluble Slightly Insoluble NO 3 All CH 3 COO All ClO 3 , ClO 4 All Cl , Br (I ) Most PbCl 2 , HgBr 2 w/ Ag + , Hg 2 2+ S 2 Groups I & II, NH 4 + Most ( Cu 2+ , Bi 3+ , Sn 4+ ) SO 3 2 , CO 3 2 , PO 4 3 Group I, NH 4 + Most OH Group I, Ba 2+ w/ Ca 2+ , Sr 2+ Most (e.g. Fe 2+ , Zn 2+ ) 6 Cations and Salt Solubilities Cations and Salt Solubilities Cation Soluble Slightly Insoluble NH 4 + All Group I (Li + , Na + , K + ) All Group II (Mg 2+ , Ca 2+ ) Most CaSO 4 , Ca/Sr(OH) 2 w/ OH- , SO 3 2- , PO 4 3- , CO 3 2- , CHEM 6BL Experiment 5: Qualitative Analysis Instructor: Dr. Sandrine Berniolles Page 3 7 Equilibrium Product Equilibrium Product z Equilibrium Product Determine whether a reaction tends to go toward products (going forward) or toward reactants (and not going) K c (aka K eq ) = [products] [reactants] z Solubility Product When reactants are a solid (e.g., an insoluble salt), [reactants] term drops out ( K sp sp ) 8 K c & K & K sp sp Examples Examples Ag + (aq) + Cl- (aq) AgCl(s) K c = [SO 3 ] 2 = 0.041 [SO 2 ] 2 [O 2 ] 2 SO 2 (g) + O 2 (g) 2 SO 3 (g) K sp = [Ag + ][Cl ] = 1.6 10-10 (favors reactants) 9 Reaction vs. Equilibrium Product Reaction vs. Equilibrium Product z Equilibrium Product It is a constant : K c or K sp never changes z To determine whether existing [reactant(s)] and [product(s)] will tend to favor the formation of more reactants or product(s): Use Reaction Product, Q c Plug concentration values into Q c Compare Q c to K c CHEM 6BL Experiment 5: Qualitative Analysis...
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This note was uploaded on 05/31/2009 for the course CHEM 6BL taught by Professor Berniolles during the Spring '08 term at UCSD.

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lecture 5 - CHEM 6BL Experiment 5: Qualitative Analysis...

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