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. _______________________________________

2. _______________________________________

3. _______________________________________

4. _______________________________________

5. _______________________________________

6. _______________________________________

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: ____________________

Q. Why does Test C support “no reaction”?

Test C: SnCl2 + I2 = reaction

SnCl4 + KI → no reaction? 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) → _________?Q. What do test 1 results tell you?

____________________

Reaction: SnCl2 + Hg(NO3)2 white solid gray-bl solid colorless

DEMO

Identify Reactant and Spectator Species

Test 2: NaCl + Hg(NO3)2 → _________?No reactionQ. What do test 2 results tell you?

____________________

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 solidQ. What do test 3 results tell you?

______________________________

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 reaction occurring• Write a net reaction.

Products and Reaction?

Reaction:SnCl2 + Hg(NO3)2 → white solid → gr-black solidTest results:Reactants = ___________ (for gr-black solid) ___________ (for white solid)

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+

Gr-black solid product? = _______

Products and Reaction

Net redox reaction (gr-bl solid product): Sn2+ (aq) + Hg2+ (aq) → _____________

Check CRC Handbook :

White intermediate insoluble product?Cl- + (mercury or tin ion) ?

_________insoluble and white

Reaction:

Add 20mL 0.10M SnCl2 to 2.0mL of 0.10M Hg(NO3)2

SnCl2 + Hg(NO3)2→ white ppt. → gray-bl ppt. ______ ________

Products and Reaction

Reaction 2: 0.10 M CuSO4 + HCl (con) → ?

DEMO

Q. What type of reaction is likely occurring?

Analysis of Reactions

_________________

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?

____________________________DEMO

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?

______________________________________

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?:

_______________________

Identify Product/s and Write A Net Rxn

Product

Q. Complete the net reaction:_ Cl- + __ [Cu(H2O)4]

2+ →

___________________

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 - → ________________

Example 11. Add a better base such as ________

Confirm Reaction

[Cu(H2O)4]2+ + 4 Cl - → _______________

DEMO

Example 21. Add an acid such as ________

Confirm Reaction

[Cu(H2O)4]2+ + 4 Cl - → ______________

DEMO