Hard-Soft Acid-Base Theory


Are the following reactions predicted to have an equilibrium constant K greater or less than one based on HSAB theory? Unless otherwise stated, assume gas-phase or hydrocarbon solution (i.e., not aqueous) and 25 °ree;C.
1.
HgI + LiF HgF + LiI
2.
TlH + Na+ Tl+ + NaH
3.
Cu(SOMe2) Cu(OSMe2)
4.
[Fe(dppe)3]2+ + 3 bipy [Fe(bipy)3]2+ + 3 dppe
5.
KI + I2 K+ + I3
6.
Me3PBBr3 + Me3NBF3 Me3PBF3 + Me3NBBr3
7.
MeHgBr + HCl MeHgCl + HBr
8.
AgCl2 + 2 CN Ag(CN)2 + 2 Cl
9.
NaI + TlF NaF + TlI
10.
HgS + ZnO HgO + ZnS
11.
Cr(SCN)3 Cr(NCS)3
12.
[Mn(dppe)3]2+ + [Pd(en)3]2+ [Mn(en)3]2+ + [Pd(dppe)3]2+
13.
HF + I F + HI
14.
LiBr + AuCl LiCl + AuBr
15.
Mn(SH)43+ + 4 OH Mn(OH)43+ + 4 SH
16.
Al(acac)3 + 3 dppe [Al(dppe)3]3+ + 3 acac
17.
F3BH + BH3 BH4 + BF3
18.
Hg(OH)2 + Mn(SH)2 Hg(SH)2 + Mn(OH)2
19.
Cr(ox)3 + W6+ Cr6+ + W(ox)3
20.
Co(CN)64− + Co3+ Co(CN)63− + Co2+
21.
NaBr + LiCl NaCl + LiBr
22.
Fe(acac)3 + Fe2+ [Fe(acac)3] + Fe3+
23.
MgCO3 + Ca2+ Mg2+ + CaCO3
24.
Fe2O3 + 3 S2− Fe2S3 + 3 O2−
25.
Me3P−BF3 + NMe3 Me3N−BF3 + PMe3
26.
Hg(NCS)2 Hg(SCN)2
27.
Ni(CO)4 Ni(CO)42+
28.
Au2O3 + 3 S2− Au2S3 + 3 O2−
29.
MgF2 + CaBr2 MgBr2 + CaF2
30.
Ni(CO)4 + 4 H2O Ni(H2O)4 + 4 CO

 

Return to Topics List

 

Solutions


  
1.

Hg+ is a softer acid than Li+, I is a softer base than F

HgI + LiF K < 1
HgF + LiI
   
   
  
2.

Tl+ is a softer acid than Na+, H is a soft base

TlH + Na+ K < 1
Tl+ + NaH
   
   
  
3.

Cu(0) is a soft acid, SOMe2 is a softer base than OSMe2

Cu(SOMe2) K < 1
Cu(OSMe2)
   
   
  
4.

Fe2+ is a hard acid, bipy (N) is a harder base than dppe (P)

[Fe(dppe)3]2+ + 3 bipy K > 1
[Fe(bipy)3]2+ + 3 dppe
   
   
  
5.

I2 is a softer acid than K+, I is a soft base

KI + I2 K > 1
K+ + I3
   
   
  
6.

BBr3 is a softer acid than BF3, PMe3 is a softer base than NMe3

Me3PBBr3 + Me3NBF3 K < 1
Me3PBF3 + Me3NBBr3
   
   
  
7.

MeHg+ is a softer acid than H+, Br is a softer base than Cl

MeHgBr + HCl K < 1
MeHgCl + HBr
   
   
  
8.

Ag+ is a soft acid, CN is a softer base than Cl

AgCl2 + 2 CN K > 1
Ag(CN)2 + 2 Cl
   
   
  
9.

Tl+ is a softer acid than Na+, I is a softer base than F

NaI + TlF K > 1
NaF + TlI
   
   
  
10.

Hg2+ is a softer acid than Zn2+, S2− is a softer base than 2−

HgS + ZnO K < 1
HgO + ZnS
   
   
  
11.

Cr3+ is a hard acid, NCS is a harder base than SCN

Cr(SCN)3 K > 1
Cr(NCS)3
   
   
  
12.

Pd2+ is a softer acid than Mn2+, dppe (P) is a softer base than en (N)

[Mn(dppe)3]2+ + [Pd(en)3]2+ K > 1
[Mn(en)3]2+ + [Pd(dppe)3]2+
   
   
  
13.

H+ is a hard acid, F is a harder acid than I

HF + I K < 1
F + HI
   
   
  
14.

Au+ is a softer acid than Li+, Br is a softer base than Cl

LiBr + AuCl K > 1
LiCl + AuBr
   
   
  
15.

Mn7+ is a hard acid, OH is a harder base than SH

Mn(SH)43+ + 4 OH K > 1
Mn(OH)43+ + 4 SH
   
   
  
16.

Al3+ is a hard acid, acac (O) is a harder base than dppe (P)

Al(acac)3 + 3 dppe K < 1
[Al(dppe)3]3+ + 3 acac
   
   
  
17.

BH3 is a softer acid than BF3, H is a soft base

F3BH + BH3 K > 1
BH4 + BF3
   
   
  
18.

Hg2+ is a softer acid than Mn2+, SH is a softer base than OH

Hg(OH)2 + Mn(SH)2 K > 1
Hg(SH)2 + Mn(OH)2
   
   
  
19.

Cr6+ is a harder acid than W6+, ox2− is a hard base

Cr(ox)3 + W6+ K < 1
Cr6+ + W(ox)3
   
   
  
20.

Co2+ is a softer acid than Co3+, CN is a soft base

Co(CN)64− + Co3+ K < 1
Co(CN)63− + Co2+
   
   
  
21.

Na+ is a softer acid than Li+, Br is a softer base than Cl

NaBr + LiCl K < 1
NaCl + LiBr
   
   
  
22.

Fe3+ is a harder acid than Fe2+, acac is a hard acid

Fe(acac)3 + Fe2+ K < 1
[Fe(acac)3] + Fe3+
   
   
  
23.

Mg2+ is a harder acid than Ca2+, CO32− is a hard base

MgCO3 + Ca2+ K < 1
Mg2+ + CaCO3
   
   
  
24.

Fe3+ is a hard acid, O2− is a harder base than S2−

Fe2O3 + 3 S2− K < 1
Fe2S3 + 3 O2−
   
   
  
25.

BF3 is a hard acid, NMe3 is a harder base than PMe3

Me3P−BF3 + NMe3 K > 1
Me3N−BF3 + PMe3
   
   
  
26.

Hg2+ is a soft acid, SCN is a softer base than NCS

Hg(NCS)2 K > 1
Hg(SCN)2
   
   
  
27.

Ni(0) is a softer acid than Ni2+, CO is a soft base

Ni(CO)4 K < 1
Ni(CO)42+
   
   
  
28.

Au3+ is a soft acid, S2− is a softer base than O2−

Au2O3 + 3 S2− K > 1
Au2S3 + 3 O2−
   
   
  
29.

Ca2+ is a softer acid than Mg2+,

MgF2 + CaBr2 K < 1
MgBr2 + CaF2
   
   
  
30.

Ni(0) is a soft acid, CO is a softer base than H2O

Ni(CO)4 + 4 H2O K < 1
Ni(H2O)4 + 4 CO
   
   
  

 

Return to Topics List