E 6 Lab
• Pre-lab report (p.170) due at the start of lab
 Single session two hour lab experiment.
Analysis of Reactions, E 6
 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.
Analysis of a Non - Reaction
Analysis of a non - reaction
E 6 Discussion
 Teams present one of the 3 reactions in discussion
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.
Analysis of a non - reaction
Example:
Ag(s)
+
silver solid
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!
Ag(s)
+
silver solid
Co(NO3)2(aq) → no visible change
clear red solution
Co(NO3)2(aq) → no visible change
clear red solution
Q. What tests or measurements could you conduct
to confirm that “no reaction” has occurred?
Ag(s) + Co(NO3)2(aq) → ?
Test to Confirm No Reaction
Reaction 2
SnCl4 (aq) + KI (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’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(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 AgNO 3(aq) and get a reaction producing
Ag(s) and Co(NO 3)2(aq).
Reaction 2
SnCl4 (aq) + KI (aq) → colorless
colorless
Co(s)
+ Ag(NO 3)2(aq) → Ag(s) + Co(NO3)2(aq)
cobalt solid
colorless soln
silver solid
red soln
Analysis of A Non-Reaction
SnCl4 (aq) + KI (aq) →
clear and colorless solutions
SnCl4 + KI
→
DEMO
Clear
and colorless
__________________
no reaction?
Q. Why does Test C support “no reaction”?
Test C: SnCl2 + I 2 = reaction
net rxn: Sn 2+ + I 2 → Sn4+ + 2 I Hexane is colorless ∴ SnCl2 + I 2 reacted
Q. Circle any test that can support “no reaction”:
A) The temperature of the original solutions and
reaction mixture shows no ∆ t°.
Note: Rxn being studied: Sn 4+ + Cl
/ - + K/+ + I- → ?
B) KCl (aq) + KI (aq) + hexane → clear, colorless phases
Sn4+ + I - are the products of a spontaneous
redox reaction (Sn 2+ + I 2) and thus do not react.
C) SnCl2 (aq) + I2(aq) + hexane → clear, colorless phases.
Answer: A) and C)
Analysis of A Non-Reaction
Sn4+(aq) + 2 I-(aq) ← I2 (aq) + Sn2+ (aq)
Analysis of Reactions
Analysis of Reactions
Reaction?
Reaction:
Add 20mL 0.10M SnCl 2 to 2.0mL of 0.10M Hg(NO 3)2
 Record your qualitative observations of
individual reagents and the reagent mixture.
1) Determine the identity of reactants/spectators.
• Record hypothesis, tests, observations, and
conclusions.
1.Record Observations:
Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2
→ ______________?
Identify Reactant and Spectator Species
Reaction:
Add 20mL 0.10M SnCl 2 to 2.0mL of 0.10M Hg(NO 3)2
Identify Reactant and Spectator Species
Reaction:
SnCl2 + Hg(NO3)2
colorless
white solid
gray-bl solid
SnCl 2 + Hg(NO 3)2→ white ppt. → gray-bl ppt.
Colorless solutions
Identify Reactant and Spectator Species
Reaction:
SnCl2 + Hg(NO3)2
colorless
white solid
gray-bl solid
Hypothesis: “Hg2+ is a reactant”.
Test :
20mL 0.10M SnCl 2 to 2.0mL of 0.10M NaNO 3 → ?
DEMO
Q. Is the above test an appropriate test of the
hypothesis?
Yes
Test:
SnCl2 + Na(NO 3) → _________?
No reaction
Q. What do the test results tell you?
Hg2+ is critical to reaction.
DEMO
Test 2:
NaCl + Hg(NO 3)2 → _________?
No reaction
Q. What do test 2 results tell you?
Sn2+ is critical to reaction.
Identify Reactant and Spectator Species
Reaction:
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 3:
Sn(NO 3) 2 + Hg(NO 3)2 → _________?
gray-bl solid
Q. What do test 3 results tell you?
Cl
- is
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?
Reaction:
SnCl2 + Hg(NO 3)2 → white solid → gr-black solid
Test results:
Reactants = Hg2+ and Sn 2+ (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?
1. Redox and
2. Sn or Hg = gr-black solid?
ppt. (Lewis acid-base)
critical to production of the white solid
Product Identification
Products and Reaction
Products and Reaction
Reaction:
Reactants:
Sn2+ + Hg2+ → gr-black solid = ?
Possible oxidation state of reactants:
Sn
Sn2+
Sn4+
Hg
Hg2+
Gr-black solid product?
= Hg
Net redox reaction (gr-bl solid product):
Sn2+ (aq) + Hg2+ (aq) → Hg(s) + Sn4+(aq)
Add 20mL 0.10M SnCl 2 to 2.0mL of 0.10M Hg(NO 3)2
White intermediate insoluble product?
Cl- + (mercury or tin ion) ?
Check CRC Handbook :
HgCl insoluble and white
(SnCl2 and SnCl 4 are soluble)
SnCl 2 + Hg(NO 3)2→ white ppt. → gray-bl ppt.
(HgCl)
(Hg)
Analysis of Reactions
Analysis of Reactions
Identify Reactants and Spectators
Reaction:
0.10 M CuSO 4 + HCl (con) → yellow-green
blue
colorless
Reaction 2:
0.10 M CuSO 4 + HCl (con) → _____________?
Q. Test that will directly determine if Cl- is a reactant?
→
Q. What type of reaction is likely occurring?
Reaction 2:
0.10 M CuSO 4 + HCl (con) → ?
Analysis of Reactions
Lewis acid-base
DEMO
Reaction:
0.10 M CuSO 4 + HCl (con) → yellow-green soln
blue
colorless
Q.Test that will directly confirm if SO 42- is a spectator?
(1)Add concentrated HNO 3 to 0.1 M CuSO 4.
→ (2)Add concentrated HCl to 0.1M Cu(NO3)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?
Reaction 2:
0.10 M CuSO 4 + HCl (con) → ?
The blue solution mixture will turn yellow-green.
DEMO
(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?
The solution mixture will remain blue
DEMO
Identify Reactants and Type of Reaction
Reactants:
Cu2+(aq) +
(blue)
Cl- (aq) → yellow-green soln
(colorless)
Type of reaction?:
Lewis acid-base (complexation)
Identify Product/s and Write A Net Rxn
Product
Chloro complex ion of Cu(II)
- Check the list of “common complex ions” or
the CRC Handook for the formula
Q. Complete the net reaction:
_ Cl- + __ [Cu(H2O)4]2+ →
4 Cl- + [Cu(H2O)4]2+ → [Cu(Cl)4]2- + 4 H2O
Confirm Reaction
[Cu(H2O) 4]2+ + 4 Cl - →
Confirm Reaction
[Cu(Cl)4]2- + 4H2O
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)?
[Cu(H 2O) 4] 2+ + 4 Cl - →
[Cu(Cl)4]2- + 4H 2O
Example 1
NH3
1. Add a better base such as ________
DEMO
Confirm Reaction
[Cu(H2O) 4]2+ + 4 Cl - →
[Cu(Cl)4]2- + 4H2O
[Cu(H2O) 4]2+ + 4 Cl - →
+
4 NH3
↓
[Cu(NH3)4]2+
+
4 H2 O
[Cu(H2O) 4]2+ + 4 Cl - →
Note:
Cu2+
bonds with NH 3
rather than Cl-.
[Cu(Cl)4]2- + 4H2O
Example 2
Ag+
1. Add an acid such as ________
[Cu(Cl)4]2- + 4H2O
+
Ag(H 2O) 2]+
↓
DEMO
[Ag(H 2O)Cl]
+
H2O
Note: Cl- bonds with Ag +
rather than Cu 2+.