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Analysis of Reactions, E 6
E 6
• Pre-lab report (p.159) 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.
Teams present one of the 3 reactions in discussion during the first hour of the next session.
Analysis of a Non - Reaction
Record your qualitative observations of individualreagents and the reagent mixture.
• Design and conduct a minimum of twoquantitative tests and experiments to confirm thatno reaction occurred.
• Do NOT conduct reference blank tests!
SnCl4 (aq) + KI (aq) → ________
DEMO
Clear and colorless
Analysis of A Non-Reaction
Example 1 SnCl4 (aq) + KI (aq) → colorless colorlessQ. Circle any test that can support “no reaction”:A) The temperature of the original solutions and reactionmixture shows no ∆ t°.
B) KCl (aq) + KI (aq) + hexane→ clear, colorless phases
C) SnCl2 (aq) +I2 (aq) + hexane → clear, colorless phases.
Answer: ________________
Analysis of A Non-Reaction
Q. Why does Test C (SnCl2 + I2 → colorless hexanephase) support “no reaction”?
Test CHexane is colorless and therefore reaction occurrednet rxn: Sn2+ + I2 → Sn4+ + 2 I-
______________________________
SnCl4 + KI → no reaction?
Analysis of a non - reaction
Example 2: Ag(s) + Co(NO3)2(aq) → no visible change silver solid clear red solution
DEMO
Q. What tests could you conduct to confirm that “noreaction” has occurred?
Reaction?
Record your qualitative observations of individualreagents and the reagent mixture.
1) Determine the identity of reactants/spectators.
• Record hypothesis, tests, observations, andconclusions.
Reaction 1: Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
DEMO
SnCl2 + Hg(NO3)2→white ppt. → gray-bl ppt.
Analysis of Reactions: Reaction 1
Reaction: Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
Test:20mL 0.10M SnCl2 to 2.0mL of 0.10M NaNO3 →
Q. Is the test an appropriate test of the hypothesis?
_______
Hypothesis: “Hg2+ is a reactant”.
Identify Reactant and Spectator Species.
Reaction 1: Add 20 mL 0.10 M SnCl2 to 2.0 mL of 0.10M Hg(NO3)2
Test 1 DEMO
Identify Reactant and Spectator Species.
SnCl2 + Na(NO3) → ?_________
Reaction: Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
Test 1:20mL 0.10M SnCl2 to 2.0mL of 0.10M NaNO3 → no reaction
Q. What do the test results tell you about the reaction?
Hypothesis: “Hg2+ is a reactant”.
Identify Reactant and Spectator Species.
___________________
Reaction 1: Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
Test 2 DEMO
1. Identify Reactant and Spectator Species.
NaCl + Hg(NO3)2 → __________?Q. What do the test results tell you about the reaction?
__________________
2. Reaction Products?
• Compare product properties toknown samples.
• Consult reference texts andcompare listed properties toobserved product properties
• Conduct tests to help confirmproduct ID.
• Write a net reaction.
Product Identification
Reaction: SnCl2 + Hg(NO3)2 → solidTests determine:“The reactants are Hg2+ and Sn2+”.
Q. Based on your knowledge and logic:1. What type of reaction is occurring?2. What is the likely identity of the solid product?
2. _______________1._________.
Product Identification
Reactants: Sn2+ + Hg2+ → solid = ?
Possible oxidation state of reactants:Sn Sn2+ Sn4+
Hg Hg2+
Solid product? = _______
Reaction 2: 0.10 M CuSO4 + HCl (con) → yellow-green solution
DEMO
Q. What type of reaction is likely occurring?
___________________________.
Analysis of Reactions: Reaction 2
Reaction: 0.10 M CuSO4 + HCl (con) → yellow-green solution blue colorless
Team tests:(1) Add concentrated HNO3 to 0.1 M CuSO4.(2) Add concentrated HCl to 0.1M Cu(NO3)2.(3) Add concentrated NaCl to 0.1 M CuSO4.
Q. Test that will directly determine if Cl- is a reactant?
____________________________DEMO
Design/conduct tests to identify reactants and spectators.
Q. If the hypothesis is correct, what will you observe when conducting the test?
Reaction: 0.10 M CuSO4 + HCl (con) → yellow-green solution blue colorless
Team tests:(1) Add concentrated HNO3 to 0.1 M CuSO4.(2) Add concentrated HCl to 0.1M Cu(NO3)2.(3) Add concentrated NaCl to 0.1 M CuSO4.
Q. Test that will directly confirm if SO42- is a spectator?
Q. If the hypothesis is correct, what will you observe when conducting the test?
______________________________________
Identify the reaction type.(after confirming reactant identities)
Reactants confirmed: Cu2+
(aq) + Cl- (aq) → yellow-green solution (blue) (colorless)
Type of reaction?:
__________________________
Identify Products and Write A Net Reaction.
HCl(con) + CuSO4(aq) → yellow-greenColorless blue
________________________________
Q. Complete the net reaction:_ Cl- + __ [Cu(H2O)4]
2+ →
Q. How might you further confirm the identity of theproduct and/or show that the product is formed from aLewis acid-base equilibrium reaction)?
Confirm the product identity.
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]2- + 4H2O
Example1. Add a better base such as ________
Confirm the product identity.
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]2- + 4H2O
DEMO
Confirm the product identity.
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]2- + 4H2O+
4 NH3
↓
[Cu(NH3)4]2+
+4 H2O Note: Cu2+ bonds with NH3
rather than Cl-.