what happens to the absorbed energy?
DESCRIPTION
What happens to the absorbed energy?. s 1. t 1. Energy. s o. EDTA Titrations. Outline. What is EDTA? Metal-Chelate Complexes ATP 4- with Mg 2+ Fe(NTA) 2 3- Fe(DTPA) 2- Chelate Effect EDTA Acid Base Properties a Y nomenclature Conditional Formation Constants EDTA Titration. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/1.jpg)
What happens to the absorbed energy?
![Page 2: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/2.jpg)
Energy
so
s1
t1
![Page 3: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/3.jpg)
![Page 4: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/4.jpg)
![Page 5: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/5.jpg)
EDTA Titrations
![Page 6: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/6.jpg)
Outline What is EDTA?What is EDTA? Metal-Chelate ComplexesMetal-Chelate Complexes
ATP4- with Mg2+
Fe(NTA)23-
Fe(DTPA)2-
Chelate EffectChelate Effect EDTAEDTA
Acid Base Properties Y nomenclature Conditional Formation Constants
EDTA TitrationEDTA Titration
![Page 7: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/7.jpg)
Metal-Chelate Complexes
Lewis Acid/Base ChemistryMonodentate
Multidentate and Chelates
![Page 8: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/8.jpg)
Review:
What is a Lewis Acid? Examples?
And a Lewis Base? Examples?
![Page 9: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/9.jpg)
Transition Metal with ligand
Central Metal ion is a Lewis Acid
Ligand – All ligands are Lewis Bases
![Page 10: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/10.jpg)
Multidentate
Multidentate or chelating ligand attaches to a metal ion through
more than one atom is said to be multidentate, or a chelating
ligand.Examples?
![Page 11: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/11.jpg)
![Page 12: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/12.jpg)
ATP4- can also form complexes with metals
![Page 13: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/13.jpg)
Complex of Iron and NTA
Fe3+ +
Fe(NTA)23-
2
![Page 14: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/14.jpg)
Medical ApplicationsMedical Applications
The Thalassemia Story
![Page 15: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/15.jpg)
![Page 16: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/16.jpg)
![Page 17: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/17.jpg)
![Page 18: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/18.jpg)
The Chelate EffectThe Chelate Effect
Question: Describe in your own words, the “chelate
effect”.
![Page 19: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/19.jpg)
The Chelate Effect!
Cd(H2O)62+ + 2
Cd(H2O)62+ + 4CH3NH2
H2N NH2
H2N
NH2
Cd
H2N
NH2
OH2
OH2
2+
+ 4 H2O
K = B2 = 8 x 109
H3CH2N
H3CH2N
Cd
NH2CH3
NH2CH3
OH2
OH2
2+
+ 4 H2O
K = B2 = 4 x 106
![Page 20: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/20.jpg)
13-2 EDTA
“EDTA is by far, the most widely used chelator in analytical chemistry. By direct titration or through indirect series of reactions, virtually every element of the periodic table can be
measured with EDTA.” - Daniel Harris
![Page 21: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/21.jpg)
Acid/Base Properties
H
H
(H6Y2+)
![Page 22: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/22.jpg)
Acid/Base Properties
H
(H5Y+)
pKa = 0.0
![Page 23: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/23.jpg)
Acid/Base Properties
(H4Y)
pKa = 0.0
pKa = 1.5
![Page 24: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/24.jpg)
Acid/Base Properties
(H3Y-)
pKa = 0.0
pKa = 1.5
-pKa = 2.0
![Page 25: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/25.jpg)
Acid/Base Properties
(H2Y-2)
pKa = 0.0
pKa = 1.5
-pKa = 2.0
- pKa = 2.7
![Page 26: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/26.jpg)
Acid/Base Properties
(HY-3)
pKa = 0.0
pKa = 1.5
-pKa = 2.0
- pKa = 2.7
pKa = 6.16
![Page 27: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/27.jpg)
Acid/Base Properties
(Y-4)
pKa = 0.0
pKa = 1.5
-pKa = 2.0
- pKa = 2.7
pKa = 6.16pKa = 10.24
![Page 28: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/28.jpg)
Fraction as Y4-
The fraction of EDTA in form Y4- is given as 4-
][][ 44 EDTAY
Y (13-3)
Concentration in the form Y4-
Total Concentration of EDTA
Fraction of EDTA ion the form YFraction of EDTA ion the form Y4-4-
![Page 29: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/29.jpg)
Fraction as Y4-
Equation 13-4 in text
654321543211
43212
3213
214
156
654321
][][][][][][4
KKKKKKKKKKKHKKKKHKKKHKKHKHH
KKKKKKY
![Page 30: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/30.jpg)
![Page 31: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/31.jpg)
Example
You make a solution of 0.10 M EDTA and you buffer the pH to (a) 10.0. What is Y4-
? (b) What is Y4- if the pH of the
solution is buffered to 11.0?
![Page 32: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/32.jpg)
][][ 44 EDTAY
Y
)10.0(36.0][ 4 MY
MY pH 036.0][ 0.104
)10.0(85.0][ 4 MY
MY pH 085.0][ 0.114
![Page 33: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/33.jpg)
EDTA reactions with Metals
Silver – Ag+
Mercury - Hg2+
Iron (III) – Fe3+
![Page 34: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/34.jpg)
EDTA
ethylenediaminetetraacetate anion => EDTA-4 => Y-4
+1 cationAg+ + Y-4 AgY-3
![Page 35: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/35.jpg)
EDTA
ethylenediaminetetraacetate anion => EDTA-4 => Y-4
+2 cation Hg+2 + Y-4 HgY-2
![Page 36: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/36.jpg)
EDTA
ethylenediaminetetraacetate anion => EDTA-4 => Y-4
+3 cationFe+3 + Y-4 FeY-1
![Page 37: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/37.jpg)
EDTA
ethylenediaminetetraacetate anion => EDTA-4 => Y-4
+n ionM+n + Y-4 MY(n-4)+
![Page 38: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/38.jpg)
EDTA [MY(n-4)+]
KMY = -------------- [M][Y-4]
[MY(n-4)+]KMY = -------------------
[M+n] * 4 * [EDTA]
[MY(n-4)+]K'MY = KMY x 4 = -------------------
[M+n] [EDTA]
][][ 44 EDTAY
Y
Conditional formation constant!Conditional formation constant!
![Page 39: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/39.jpg)
![Page 40: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/40.jpg)
Example
Calculate the concentration of Ni2+ in a solution that was prepared by mixing 50.0 mL of 0.0300 M Ni2+ with 50.0 mL of 0.0500 M EDTA. The solution was buffered to pH of 3.00. Two Parts
1. Reaction2. Then equilibrium is established
![Page 41: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/41.jpg)
EDTA Titrations
![Page 42: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/42.jpg)
![Page 43: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/43.jpg)
Figure 13-10 Theoretical titration curves
![Page 44: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/44.jpg)
EXAMPLE:
Calculate the conditional constant:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.
pCa at Equivalence
Equivalence Volume
pCa at Pre-Equivalence Point
pCa at Post-Equivalence Point
pCa at Initial Point
![Page 45: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/45.jpg)
Example
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.
[CaY-2]K'CaY = KCaY * 4 = ----------------
[Ca+2] * [EDTA]
where Y4- = 0.36 at pH = 10.0
K'CaY = KCaY * 4 = 4.9 x 1010 * 0.36 = 1.8 x 1010
KCaY = 4.9 x 1010
![Page 46: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/46.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.Equivalence Volume 1 Mole of EDTA = 1 Mole of MetalM1V1 = M2V2 (Careful of Stoichiometry)
50.0 mL (0.0500 M) = 0.1000 M (V2)V2 = 25.0 mL
![Page 47: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/47.jpg)
EXAMPLE:
K'CaY = 1.8 x 1010
0.00 mL EDTA added
pCa = - log[Ca+2]
Initial Point
= - log(0.00500 M) = 2.301
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.
![Page 48: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/48.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.At 25.0 mL (Equivalence Point)At 25.0 mL (Equivalence Point)
Ca2+ + Y4- -> CaY2-
Before 0.0025 moles 0.0025 moles
-
After - - 0.0025 moles
What can contribute to Ca2+ “after” reaction?
![Page 49: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/49.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.
Ca2+ + Y4- CaY2-
I - - 0.0025 moles/V
C +x +x -x
E +x + x 0.0333 –x
]][[
][2
2'
CaEDTA
CaYK CaY
2' 0333.0
x
xK CaY
X = [Ca2+] = 1.4 x10-6
pX = p[Ca2+] = 5.866
0.0025moles/0.075 L0.0025moles/0.075 L
![Page 50: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/50.jpg)
Pre-Equivalence Point
Let’s try 15 mL
![Page 51: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/51.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.At 15.0 mL Ca2+ + Y4- -> CaY2-
Before 0.0025 moles 0.0015 moles
-
After 0.0010 moles - 0.0015 moles
What can contribute to Ca2+ after reaction?
K’CaY = 1.8 x 1010
negligiblenegligible
![Page 52: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/52.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.At 15.0 mL
[Ca2+] = 0.0010 moles/0.065 L[Ca2+] = 0.015384 Mp [Ca2+] = 1.812
![Page 53: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/53.jpg)
Post Equivalence Point
Let’s Try 28 ml
![Page 54: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/54.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.At 28.0 mL Ca2+ + Y4- -> CaY2-
Before 0.0025 moles 0.0028 moles
-
After - 0.0003 moles
0.0025 moles
What can contribute to Ca2+ after titration?
![Page 55: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/55.jpg)
EXAMPLE:
Derive a curve (pCa as a function of volume of EDTA) for the titration of 50.0 mL of 0.0500 M Ca+2 with 0.1000 M EDTA in a solution buffered to a constant pH of 10.0.
Ca2+ + Y4- CaY2-
I - 0.0003 moles/V 0.0025 moles/V
C +x +x -x
E +x 0.003846 + x 0.03205 –x
]][[
][2
2'
CaEDTA
CaYK CaY
))(003846.0(
03205.0'
xx
xK CaY
X = [Ca2+] = 4.6 x10-10
pX = p[Ca2+] = 9.334
0.078 L
![Page 56: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/56.jpg)
![Page 57: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/57.jpg)
Experimental Considerations
![Page 58: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/58.jpg)
EDTA Titration Techniques
Erichrome Black T
MgIn + EDTA MgEDTA + In
(red) (colorless) (blue)
![Page 59: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/59.jpg)
Figure 13-13 Guide to EDTA titrations, light color, pH range for quantitative analysis, dark area where ammonia must be present
![Page 60: What happens to the absorbed energy?](https://reader036.vdocuments.site/reader036/viewer/2022062321/568134c0550346895d9be2a4/html5/thumbnails/60.jpg)