LAB 2B (2012) - SISTEMA NEUROENDOCRINO EN INSECTOS (estudiantes).doc
Lab one: Parts 1 and 2A Answer Lab two: Parts 2B and 3chem125/W08/E3W08lab2key.pdf · 1 Experiment...
Transcript of Lab one: Parts 1 and 2A Answer Lab two: Parts 2B and 3chem125/W08/E3W08lab2key.pdf · 1 Experiment...
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Experiment Three
Lab one: Parts 1 and 2A Lab two: Parts 2B and 3
11A
18VIIIA
1H
1s1
2IIA
13
IIIA14
IVA15
VA16
VIA17
VIIA
2He1s2
3Li
2s1
4Be
2s2
5B
2s22p1
6C
2s22p2
7N
2s22p3
8O
2s22p4
9F
2s22p5
1 0Ne
2s22p6
1 1Na
3s1
1 2Mg
3s2
3 IIIB
4 IVB
5 VB
6VIB
7VIIB
8VIIIB
9 !
10 VIIIB
11 IB
12 IIB
1 3Al
3s23p1
1 4Si
3s23p2
1 5P
3s23p3
1 6S
3s23p4
1 7Cl
3s23p5
1 8Ar
3s23p6
1 9K
4s1
2 0Ca
4s2
2 1Sc
4s23d1
2 2Ti
4s23d2
2 3V
4s23d3
2 4Cr
4s13d5
2 5Mn
4s23d5
2 6Fe
4s23d6
2 7Co
4s23d7
2 8Ni
4s23d8
2 9Cu
4s13d10
3 0Zn
3d1 04s2
3 1Ga
4s24p1
3 2Ge
4s24p2
3 3As
4s24p3
3 4Se
4s24p4
3 5Br
4s24p5
3 6Kr
4s24p6
3 7Rb
5s1
3 8Sr
5s2
3 9Y
5s24d1
4 0Zr
5s24d2
4 1Nb
5s24d3
4 2Mo
5s14d5
4 3Tc
5s24d5
4 4Ru
5s14d7
4 5Rh
5s14d8
4 6Pd
4d10
4 7Ag
5s14d10
4 8Cd
4d1 05s2
4 9In
5s25p1
5 0Sn
5s25p2
5 1Sb
5s25p3
5 2Te
5s25p4
5 3I
5s25p5
5 4Xe
5s25p6
5 5Cs
6s1
5 6Ba
6s2
5 7
La*
6s25d1
7 2Hf
6s25d2
7 3Ta
6s25d3
7 4W
6s25d4
7 5Re
6s25d5
7 6Os
6s25d6
7 7Ir
6s25d7
7 8Pt
6s15d9
7 9Au
6s15d10
8 0Hg
5d1 06s2
8 1Tl
6s26p1
8 2Pb
6s26p2
8 3Bi
6s26p3
8 4Po
6s26p4
8 5At
6s26p5
8 6Rn
6s26p6
8 7Fr
7s1
8 8Ra
7s2
8 9Ac#
7s26d1
1 0 4 +
7s26d2
1 0 5 +
7s26d3
1 0 6 +
7s26d4
1 0 7 +
7s26d5
1 0 8 +
7s26d6
1 0 9 +
7s26d7
+ Element synthesized,
but no official name assigned
Halogens (Family VIIA) used in Parts 2 and 3
Q. Possible oxidation states?
Answer: 0 or -1
Halogens used in Parts 2 and 3
Chlorine Bromine Iodine Cl2(g) Br2(l) I2(s)
Increasing molecular weight
HALOGENS
Cl2 = ChlorineExist as diatomic NONPOLAR moleculesOxidation state = zeroOxidizing agents that react to form halides: Cl2 + 2 e- → 2 Cl-
2
HALIDES
Cl- in NaCl(s)
Exist as anions in salts Salt names end in ide (e.g., sodium bromide…) Oxidation state = -1. Reducing agents
Halogens (Parts 2 and 3)
The halogens will be provided in water solution.
Chlorine water Bromine water Iodine water
similar in visual appearance
Halides (Parts 2 and 3)
Sodium halide (s) Sodium halide (aq)
The halides are provided as sodium salts in watersolution.
The sodium salts of the halides visually look the samein the solid state and in aqueous solution.
Part 2A. Color and Solubility of the Halides and Halogens
Determine and compare the color andsolubility of the halides and halogens in waterand hexane.
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Color of the Halogens
The color of the halogens is solvent dependent.
Example
Iodine versus Iodine water (dilute and more concentrated)
DEMO
Solvent Polarity Reminders
Polar (e.g., water) and non-polar (e.g., hexane)liquids are immiscible.
DEMO
Polar and non-polar liquids form separate phases:
DEMO
Salt Solubility Reminders
“Like attracts like”
Salts are soluble and dissociate in polar solvents. Salts are NOT soluble and do not dissociate in non-polar solvents.
DEMO
Q. A yellow-brown aqueous solution contains anunidentified halogen. If hexane is added to the solutiontwo phases form where the upper phase is pink and thelower phase colorless. Identify the halogen
Answer:____________DEMO
+ hexane →
Iodine
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Part 2B. Reactivity of the Halogens and Halides.
Collect experimental data on the reactivity of thehalogens and halides.
Discussion questions 3 and 4, p.96
OA Strength of Chlorine versus Bromine?
•# rxns.•Br2
•Cl2
•# rxns.•Br-•Cl-
Table: Oxidizing agents on one side andreducing agents on the other side.
SeeexpandedTable, p.77
Caution: Check data. Does it make sense?
00# rxns.
0No rxnBr2
0No rxnCl2
# rxns.Br-Cl-
“ These results don’t make sense!”
One combination of halogen and halide should react-- the stronger OA and RA agent!
Interpreting Experiment Results
1) Cl2 + 2 Br- → 2 Cl- + Br2
RA OA
1) OA strength: ___ >___
2) OA strength: ___ >___
OA RA
Cl2 Br2
2) Br2 + 2 Cl- → 2 Br- + Cl2
Br2 Cl2
“Reaction 1) or 2) should occur!”
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Answer.________________________________
Q. The electronegativity of chlorine = 3.0 and bromine = 2.8. Based strictly on electronegativity values, will Br2(aq) + NaCl(aq) react?
Br-Br2
Cl-Cl2
Reducing AgentOxidizing Agent
No. Br2 and Cl- are the weaker OA and RA.
List the Oxidizing and reducing agent species andindicate the comparative strength
Experiment ResultsQ. Br2 (aq) + NaCl (aq) → reaction or no reaction?
→Add hexane
Br2 (aq)+ 2 NaCl (aq) ________________no reaction
DEMO
Interpreting Experiment ResultsQ2. Identify the species present in the upper and lowerphases upon addition of hexane to the reaction mixture.
Br2
Na+
Cl - →Add hexane
Br2 (aq)+ 2 NaCl (aq) no reaction
Part 3. Analysis of Redox Reactions
Identify reactants and spectators in redox reactions.
- Non-reactive redox species (K+, Na+, NO3- ) make
good substitutes for an omitted species in tests.
Identify products; write a net reaction- Compare properties to known substances- use the CRC Handbook.
Rank the oxidizing or reducing agent strength ofspecies in the reaction
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“Help. I spilled Iodine!”
Example: I2 + SnCl2 → ?
DEMO: Addtin(II) chloride toiodine spot!
SnCl2(aq) + I2(aq) → clear and colorless product
Analysis of Reaction1. Record Observations
2. Design and Interpret Reference Blank TestsReaction: SnCl2(aq) + I2(aq) → ?
Reference Blank Test:
NaCl(aq) + I2(aq) no reaction
Conclusion:
“Sn2+ is a reactant”.DEMO
2. Design and Interpret Reference Blank TestsReaction: SnCl2(aq) + I2(aq) → ?
Reference Blank Test:
Sn(NO3)2(aq) + I2(aq) reaction
Conclusion:
“Cl- is a spectator”.
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3) Identify OA and RA Reactants
Q. Identify the oxidizing and reducing agentreactants:
Sn2+(aq) + I2(aq) → ?
RA OA______________
4) Identify Products and Write a Net Reaction
Observation: Light brown I2(aq) color fades.
I2(aq) → _______________ Sn2+(aq) +
Knowledge: Sn2+ is the reducing agent.
2I-(aq) + Sn4+
(aq)
Sn2+aq) + I2(aq) → Sn4+
(aq) + 2I - (aq)
RA OA OA RA
5). Strength of the Reducing and Oxidizing Agents?
I2 Sn4+Sn2+ I- RA strength: ____ >___ OA strength: ___ >___
“The reactants are the stronger OA and RA”.
List the species and indicate OA and RA strength:
OA F2 Co3+
Br2
K+
Q. Identify the reactants in the redox reaction,CoF3(aq) + KBr(aq) → ?
given OA Strength: F2 > Co3+ > Br2 > K+
RA __ __ __ __
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List the species and indicate OA and RA strength:
OA F2 Co3+
Br2
K+
Q. Identify the reactants in the redox reaction,CoF3(aq) + KBr(aq) → ?
given OA Strength: F2 > Co3+ > Br2 > K+
RA F-
Co2+
Br-
K
Note (circle) all species present in the reaction.
OA F2
Co3+
Br2
K+
Q. Identify the reactants in the redox reaction,CoF3(aq) + KBr(aq) → ?
given OA Strength: F2 > Co3+ > Br2 > K+
RA F-
Co2+
Br-
K
Identify which species will react
OA F2
Co3+
Br2
K+
Q. Identify the reactants in the redox reaction,CoF3(aq) + KBr(aq) → ?
given OA Strength: F2 > Co3+ > Br2 > K+
RA F-
Co2+
Br-
K
OA F2 Co3+
Br2
K+
Q. Identify the products in the redox reaction,CoF3(aq) + KBr(aq) → ?
given OA Strength: F2 > Co3+ > Br2 > K+
RA F-
Co2+
Br-
K
Answer: Co2+aq) + Br2(aq)