Ch 11. Group 1 (Alkali Metals)
description
Transcript of Ch 11. Group 1 (Alkali Metals)
![Page 1: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/1.jpg)
Ch 11. Group 1 (Alkali Metals)
![Page 2: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/2.jpg)
2
Hvap (in kJ/mol) for Metals
![Page 3: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/3.jpg)
3
Elemental Metals
Synthesis by electrolysis
2 KOH K (m) + ½ O2 (g) + H2O (l)
Sir Humphrey Davy, 1807 (K, Na)
Reactivities:
M (m) + H2O MOH (aq) + ½ H2 (g)
Li is rapid; Na to Cs is increasingly violent, explosive
![Page 4: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/4.jpg)
4
Elemental properties
![Page 5: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/5.jpg)
5
Pourbaix s-block
![Page 6: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/6.jpg)
6
Born-Haber approach
![Page 7: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/7.jpg)
7
Solution and lattice enthalpies
![Page 8: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/8.jpg)
8
Exchange / Displacement Large ion salt + small ion salt is better than two salts with
large and small ions combined.
Example: Salt ΔHL sum
CsF 750
NaI 705 1455 kJ/mol
CsI 620
NaF 926 1546
This can help predict some reactions like displacements, ion exchange, thermal stability.
![Page 9: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/9.jpg)
9
Crown ethers and cryptands
Formation constants with alkali metal cations
[M(OH2)n]+ + ether = [M(ether)]+ + n H2O Kf
![Page 10: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/10.jpg)
10
Alkides, electrides2 Na(s) Na+ (solv) + Na- (solv)
Na+(solv) [Na(crypt)]+Na- (s) en = ethylenediammine, H2NCH2CH2NH2
en
N2
2,2,2 crypt
ΔHrxn = 2ΔHat(Na) + I(Na) – Ea(Na) + ΔHsolv, cation + ΔHsolv, anion
sodide anion
= 2(108) + 514 - 52 + ? + ?
? We know that ΔHhyd(Na+) = - 400 kJ/mol
![Page 11: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/11.jpg)
11
Electrides
[Cs(18-C-6)2]+e-
Cs(15-C-5)2 Cs+ is the green sphere, electride anion is pink
![Page 12: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/12.jpg)
12
Li clusters
![Page 13: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/13.jpg)
Ch 12. Group 2 (Alkaline Earths)
![Page 14: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/14.jpg)
14
Element properties
![Page 15: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/15.jpg)
15
Be compounds
![Page 16: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/16.jpg)
16
Organo Be compounds
![Page 17: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/17.jpg)
17
Organometallics synthesis
Hg(CH3)2 + Be (s) → Be(CH3)2 + Hg (l) transmetallation
BuLi + BeCl2 → Bu2Be + 2 LiCl (s) halogen exchange
BuCl + 2 Li(s) → BuLi + LiCl (s) lithiation
BuLi + C6H6 → LiC6H5 + C4H10
Mg(s) + RX → 2 RMgX insertion (Grignard) insertion
R2Be + 2 MgCl2(s)
BeCl2
![Page 18: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/18.jpg)
18
Thermal stability of metal carbonates
An important industrial reaction involves the thermolysis of metal carbonates to form metal oxides according to:
MCO3 (s) → MO (s) + CO2 (g) G must be negative for the reaction to proceed. At the lowest
reaction temp:
G = 0 and Tmin = H / S S is positive because gas is liberated. As T increases, G
becomes more negative (i.e. the reaction becomes more favorable). S depends mainly on S0{CO2(g)} and is almost independent of M.
![Page 19: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/19.jpg)
19
Thermal stability of metal carbonates
MCO3 (s) → MO (s) + CO2 (g)
Tmin almost directly proportional to H.
HL favors formation of the oxide (smaller anion) for smaller cations.
So Tmin for carbonates should increase with cation size.
![Page 20: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/20.jpg)
20
Carbonate stabilities
![Page 21: Ch 11. Group 1 (Alkali Metals)](https://reader035.fdocuments.net/reader035/viewer/2022081421/56813fef550346895daafb5c/html5/thumbnails/21.jpg)
21
Mg2+ chelation with EDTA
EDTA = ethylenediaminetetraacetate