Analysis of Reactions, E 6 E 6 • 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. 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 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 Example 1 : Ag(s) + Co(NO 3 ) 2 (aq) → no visible change silver solid clear red solution DEMO Q. What tests or measurements could you conduct to confirm that “no reaction” has occurred? Ag(s) + Co(NO 3 ) 2 (aq) → ? Some example of tests or measurements : 1. Show that the pH of Co(NO 3 ) 2(aq) doesn’t change upon addition of silver metal. (Use a pH paper or pH meter) 2. Show that the concentration of Co(NO 3 ) 2(aq) doesn’t change upon addition of silver. (Use a spectrophotometer to show no delta in absorbance). 3. Show that the mass of Ag remains constant (Use a balance) 4. Show that the temperature of Co(NO 3 ) 2(aq) doesn’t change (Use a thermometer) 5. Show that the Co(NO 3 ) 2(aq) does not contain silver ions (Add a ppt. agent such as NaCl and get no AgCl ppt) 6. Add Co(s) to AgNO 3 (aq) and get a reaction producing Ag(s) and Co(NO 3 ) 2 (aq). SnCl 4 (aq) + KI (aq) → __________________ clear and colorless solutions DEMO Clear and colorless Analysis of A Non-Reaction Reaction 2 SnCl 4 (aq) + KI (aq) → ?
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Analysis of Reactions, E 6
E 6
• 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.
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.
• Conduct a minimum of two quantitative tests andexperiments to confirm that no reaction occurred.
• Tests should demonstrate that no change inreactant properties has occurred.
• Do NOT conduct reference blank tests!
Analysis of a non - reaction
Example 1: Ag(s) + Co(NO3)2(aq) → no visible change silver solid clear red solution
DEMO
Q. What tests or measurements could you conduct toconfirm that “no reaction” has occurred?
Ag(s) + Co(NO3)2(aq) → ?
Some example of tests or measurements:1. Show that the pH of Co(NO3)2(aq) doesn’t change upon
addition of silver metal. (Use a pH paper or pH meter)
2. Show that the concentration of Co(NO3)2(aq) doesn’tchange upon addition of silver. (Use a spectrophotometerto show no delta in absorbance).
3. Show that the mass of Ag remains constant (Use abalance)
4. Show that the temperature of Co(NO3)2(aq) doesn’t change(Use a thermometer)
5. Show that the Co(NO3)2(aq) does not contain silver ions(Add a ppt. agent such as NaCl and get no AgCl ppt)
6. Add Co(s) to AgNO3(aq) and get a reaction producingAg(s) and Co(NO3)2(aq).
SnCl4 (aq) + KI (aq) → __________________ clear and colorless solutions
DEMO
Clear and colorless
Analysis of A Non-Reaction
Reaction 2 SnCl4 (aq) + KI (aq) → ?
Reaction 2
SnCl4 (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
C) SnCl2 (aq) + I2(aq) + hexane → clear, colorless phases.
Answer: A) and C)
Q. Why does Test C support “no reaction”?
Note: Rxn being studied: Sn4+ + Cl- + K+ + I- → ?/ /
Test C: SnCl2 + I2 = reactionnet rxn: Sn2+ + I2 → Sn4+ + 2 I-
Hexane is colorless ∴ reaction occurred
Sn4++ I- are the products of a spontaneous
redox reaction and thus do not react.
SnCl4 + KI → no reaction?
If Sn4+ + I- react the products = Sn2+ + I2
Reaction?
Record your qualitative observations ofindividual reagents and the reagent mixture.
1) Determine the identity of reactants/spectators.
• Record hypothesis, tests, observations, andconclusions.
Reaction:
Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
DEMO
SnCl2 + Hg(NO3)2→ white ppt. → gray-bl ppt.Colorless solutions
Analysis of Reactions
Record Observations:
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 → ?
Q. Is test 1 an appropriate test of the hypothesis?
Yes
Hypothesis: “Hg2+ is a reactant”.
Identify Reactant and Spectator Species
Reaction: SnCl2 + Hg(NO3)2 white solid gray-bl solid colorless
DEMO
Identify Reactant and Spectator Species
Test 1: SnCl2 + Na(NO3) → _________?No reaction
Q. What do test 1 results tell you?
Hg2+ is critical to reaction.
Reaction: SnCl2 + Hg(NO3)2 white solid gray-bl solid colorless
DEMO
Identify Reactant and Spectator Species
Test 2: NaCl + Hg(NO3)2 → _________?No reaction
Q. What do test 2 results tell you?
Sn2+ is critical to reaction.
Reaction: Add 20mL 0.10 M SnCl2 to 2.0 mL of 0.10 M Hg(NO3)2
white solid gray-bl solid
Identify Reactant and Spectator Species
Test 3: Sn(NO3)2 + Hg(NO3)2 → _________?gray-bl solid
Q. What do test 3 results tell you?
Cl -is critical to production of the white solid
Products and Reaction?
• Compare product properties toknown samples.
• Consult reference texts andcompare listed properties toobserved product properties
• Conduct tests to help confirmproduct ID.
• Indicate type of reactionoccurring
• Write a net reaction.
Products and Reaction?
Reaction:SnCl2 + Hg(NO3)2 → white solid → gr-black solidTest results:Reactants = Hg2+ and Sn2+ (for gr-black solid) Cl- and ___? (for white solid)
1. What type of reaction is occurring?2. What is the likely identity of the solid product?
2. Sn or Hg = gr-black solid?1. Redox andppt. (Lewis acid-base)
Product Identification
Reactants: Sn2+ + Hg2+ → gr-black solid = ?
Possible oxidation state of reactants:Sn Sn2+ Sn4+
Hg Hg2+
Gr-black solid product? = Hg
Products and Reaction
Net redox reaction (gr-bl solid product): Sn2+
(aq) + Hg2+ (aq) → Hg(s) + Sn4+
(aq)
Check CRC Handbook :
White intermediate insoluble product?Cl- + (mercury or tin ion) ?
HgCl insoluble and white(SnCl2 and SnCl4 are soluble)
Reaction:
Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
SnCl2 + Hg(NO3)2→ white ppt. → gray-bl ppt. (HgCl) (Hg)
Products and Reaction
Reaction 2: 0.10 M CuSO4 + HCl (con) → ?
DEMO
Q. What type of reaction is likely occurring?
Analysis of Reactions
Lewis acid-base
Reaction: 0.10 M CuSO4 + HCl (con) → yellow-green blue colorless
(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?
→
The solution mixture will remain blueDEMO
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 soln
blue colorless
(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?
→
The blue solution mixture will turn yellow-green.
DEMO
Q. If the hypothesis is correct, what will you observe when conducting the test?
Identify Reactants and Type of Reaction
Reactants: Cu2+
(aq) + Cl- (aq) → yellow-green soln (blue) (colorless)
Type of reaction?:
Lewis acid-base (complexation)
Identify Product/s and Write A Net Rxn
Product
4 Cl- + [Cu(H2O)4]2+ → [Cu(Cl)4]
2- + 4 H2O
Q. Complete the net reaction:_ Cl- + __ [Cu(H2O)4]
2+ →
Chloro complex ion of Cu(II)
Q. How might you further confirm the identity ofthe product and/or show that the product is formedfrom a Lewis acid-base equilibrium reaction)?
Confirm Reaction
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]2- + 4H2O
Example 11. Add a better base such as ________
Confirm Reaction
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]
2- + 4H2O
DEMO
NH3
Confirm Reaction
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]
2- + 4H2O
+4 NH3
↓
[Cu(NH3)4]2+
+4 H2O
Note: Cu2+ bonds withNH3 rather than Cl-.
Example 21. Add an acid such as ________
Confirm Reaction
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]
2- + 4H2O
DEMO
Ag+
Confirm Reaction
[Cu(H2O)4]2+ + 4 Cl - → [Cu(Cl)4]
2- + 4H2O
+ Ag(H2O)2]
+
↓
[Ag(H2O)Cl]+
H2O
Note: Cl- bonds with Ag+
rather than Cu2+.
Questions?Contact [email protected]
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