E 6 Lab. Pre-lab report (p.170) due at the start of lab. Single session two hour lab experiment. Teams analyze 3 assigned reactions.

Transcription

1 Analysis of Reactions, E 6 E 6 Lab Pre-lab report (p.170) due at the start of lab Single session two hour lab experiment. Teams analyze 3 assigned reactions. - one reaction may or may not be a non-reaction. Team report is due at the end of lab. - report = write up of the analysis of the 3 reactions. E 6 Discussion Teams present one of the 3 assigned reactions during the first hour of the next session. Present what you did in lab and wrote up for your lab report, regardless of whether it is right or wrong. Present what you actually did in LAB, and the logic you used to justify your conclusions. If what you did in lab was wrong, explain where you went wrong and why. Present things you could have done better, if any, to analyze the reaction.

2 Analysis of a Non - Reaction Record your qualitative observations of individual reagents and the reagent mixture. Conduct a minimum of two quantitative tests and experiments to confirm that no reaction occurred. Tests should demonstrate that no change in reactant properties has occurred. Do NOT conduct reference blank tests! Analysis of a non - reaction Analysis of a non - reaction Example: Ag(s) + Co(NO 3 ) 2 (aq) no visible change silver solid clear red solution Ag(s) + Co(NO 3 ) 2 (aq) no visible change silver solid clear red solution Q. What tests or measurements could you conduct to confirm that no reaction has occurred?

3 Ag(s) + Co(NO3)2(aq)? Some example of tests or measurements: 1. Analysis of A Non-Reaction Reaction 2 SnCl 4 (aq) + KI (aq)? Reaction 2 SnCl 4 (aq) + KI (aq) colorless colorless Q. Circle any test that can support no reaction : A) The temperature of the original solutions and reaction mixture shows no t. B) KCl (aq) + KI (aq) + hexane clear, colorless phases SnCl 4 (aq) + KI (aq) clear and colorless solutions Clear and colorless C) SnCl 2 (aq) + I 2 (aq) + hexane clear, colorless phases. Answer:

4 Analysis of A Non-Reaction SnCl 4 + KI no reaction? Q. Why does Test support no reaction? Reaction? Record your qualitative observations of individual reagents and the reagent mixture. 1) Determine the identity of reactants/spectators. Record hypothesis, tests, observations, and conclusions.

5 Analysis of Reactions Analysis of Reactions Add 20mL 0.10M SnCl 2 to 2.0mL of 0.10M Hg(NO 3 ) 2 1.Record Observations: Identify Reactant and Spectator Species Add 20mL 0.10M SnCl 2 to 2.0mL of 0.10M Hg(NO 3 ) 2 Hypothesis: Hg 2+ is a reactant. Test : 20mL 0.10M SnCl 2 to 2.0mL of 0.10M NaNO 3? Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2? SnCl 2 + Hg(NO 3 ) 2 white ppt. gray-bl ppt. Colorless solutions Q. Is the above test an appropriate test of the hypothesis?

6 Identify Reactant and Spectator Species SnCl 2 + Hg(NO 3 ) 2 white solid gray-bl solid colorless Identify Reactant and Spectator Species SnCl 2 + Hg(NO 3 ) 2 white solid gray-bl solid colorless Identify Reactant and Spectator Species Add 20mL 0.10 M SnCl 2 to 2.0 ml of 0.10 M Hg(NO 3 ) 2 white solid gray-bl solid Test: SnCl 2 + Na(NO 3 )? Q. What do the test results tell you? Test 2: NaCl + Hg(NO 3 ) 2? Q. What do test 2 results tell you? Test 3: Sn(NO 3 ) 2 + Hg(NO 3 ) 2? gray-bl solid Q. What do test 3 results tell you?

7 Reaction Products? Compare product properties to known samples. Consult reference texts and compare listed properties to observed product properties Conduct tests to help confirm product ID. Indicate type of reaction occurring Write a net reaction. Products and Reaction? SnCl 2 + Hg(NO 3 ) 2 white solid gr-black solid Test results: Reactants = 1. What type of reaction is occurring? 2. What is the likely identity of the solid product? Reactants: Product Identification Possible oxidation state of reactants: Gr-black solid product? =

8 Products and Reaction Net redox reaction (gr-bl solid product): White intermediate insoluble product? Check properties listed in CRC Handbook : Products and Reaction Add 20mL 0.10M SnCl 2 to 2.0mL of 0.10M Hg(NO 3 ) 2 SnCl 2 + Hg(NO 3 ) 2 white ppt. gray-bl ppt. Analysis of Reactions Reaction 2: 0.10 M CuSO 4 + HCl (con)?

9 Analysis of Reactions Reaction 2: 0.10 M CuSO 4 + HCl (con)? Q. What type of reaction is likely occurring? Identify Reactants and Spectators 0.10 M CuSO 4 + HCl (con) yellow-green blue colorless Q. Test that will directly determine if Cl - is a reactant? (1)Add concentrated HNO 3 to 0.1 M CuSO 4. (2)Add concentrated HCl to 0.1M Cu(NO 3 ) 2. (3) Add concentrated NaCl to 0.1 M CuSO 4. Q. If the hypothesis is correct, what will you observe when conducting the test? Analysis of Reactions Reaction 2: 0.10 M CuSO 4 + HCl (con)?

10 0.10 M CuSO 4 + HCl (con) yellow-green soln blue colorless Q.Test that will directly confirm if SO 4 2- is a spectator? (1)Add concentrated HNO 3 to 0.1 M CuSO 4. (2)Add concentrated HCl to 0.1M Cu(NO 3 ) 2. (3) Add concentrated NaCl to 0.1 M CuSO 4. Q. If the hypothesis is correct, what will you observe when conducting the test? Identify Reactants and Type of Reaction Reactants: Cu 2+ (aq) + Cl- (aq) yellow-green soln (blue) (colorless) Type of reaction?: Identify Product/s and Write A Net Rxn Product - Check the list of common complex ions or the CRC Handook for the formula Q. Complete the net reaction: _ Cl - + [Cu(H 2 O) 4 ] 2+

11 Confirm Reaction Confirm Reaction Confirm Reaction [Cu(H 2 O) 4 ] Cl - [Cu(H 2 O) 4 ] Cl - [Cu(Cl) 4 ] H 2 O [Cu(H 2 O) 4 ] Cl - Q. How might you further confirm the identity of the product and/or show that the product is formed from a Lewis acid-base equilibrium reaction)? Example 1 1. Add a better base such as Example 2 1. Add an acid such as