ELECTRON MICROSCOPY OF DNA MOLECULES STAINED WITH HEAVY METAL SALTS
IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal...
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Transcript of IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal...
![Page 1: IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal reacting with a non-metal. 2 Na (s) + Cl 2(g) 2 NaCl.](https://reader036.fdocuments.in/reader036/viewer/2022082517/56649f295503460f94c42133/html5/thumbnails/1.jpg)
IX. Salts and Hydrolysis Salts are simply ionic compounds.
Salts can be formed by:
1. A metal reacting with a non-metal.2 Na(s) + Cl2(g) 2 NaCl(s)
2. An acid reacting with a base.KOH(aq) + HCl(aq) H2O(l) + KCl(aq)
3. An acid reacting with a metal.Mg(s) + 2 HCl(aq) H2(g) + MgCl2(aq)
Salts often include polyatomic ions:eg: Na3PO4 NH4Cl CaSO4
![Page 2: IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal reacting with a non-metal. 2 Na (s) + Cl 2(g) 2 NaCl.](https://reader036.fdocuments.in/reader036/viewer/2022082517/56649f295503460f94c42133/html5/thumbnails/2.jpg)
All salts are considered at least slightly soluble (recall Ksp) and many are highly soluble.
Many salts when dissolved in solution will change the pH of the solution – this is known as a hydrolysis reaction.
eg: Na2CO3 – sodium carbonate
Na2CO3(s) 2 Na+(aq) + CO3
2-(aq)
dissociation first, then…
CO32-
(aq) + H2O(l) HCO3-(aq)
+ OH-(aq)
Hydrolysis causes some OH- to be produced.
a solution of Na2CO3 is actually basic.
![Page 3: IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal reacting with a non-metal. 2 Na (s) + Cl 2(g) 2 NaCl.](https://reader036.fdocuments.in/reader036/viewer/2022082517/56649f295503460f94c42133/html5/thumbnails/3.jpg)
eg: NH4Cl – ammonium chloride
NH4Cl(s) NH4+
(aq) + Cl-(aq)
then…
NH4+
(aq) + H2O(l) NH3(aq) + H3O+
(aq)
a solution of NH4Cl is actually acidic.
![Page 4: IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal reacting with a non-metal. 2 Na (s) + Cl 2(g) 2 NaCl.](https://reader036.fdocuments.in/reader036/viewer/2022082517/56649f295503460f94c42133/html5/thumbnails/4.jpg)
eg: NaHCO3 – sodium bicarbonate
NaHCO3(s) Na+(aq) + HCO3
-(aq)
Does HCO3- act as an acid or a base?
HCO3-(aq) + H2O(l) H2CO3(aq)
+ OH-(aq)
a solution of NaHCO3 is basic.
Compare KA with KB:
KA = 5.6 x 10-11 KB = 1.0 x 10-14
4.3 x 10-7 = 2.3 x 10-8
KA(H2CO3)
HCO3- acts as a base.
In these examples notice that Na+ and Cl- do not react with water. They have no H+ to donate and no tendency to accept H+ from H2O.
![Page 5: IX.Salts and Hydrolysis Salts are simply ionic compounds. Salts can be formed by: 1.A metal reacting with a non-metal. 2 Na (s) + Cl 2(g) 2 NaCl.](https://reader036.fdocuments.in/reader036/viewer/2022082517/56649f295503460f94c42133/html5/thumbnails/5.jpg)
General Rules for Hydrolysis:
1. Cations (+ ions) of strong bases do not hydrolyze.eg: groups I & II metal ions (Na+, K+, Ca2+…)
2. Anions (- ions) of strong acids do not hydrolyze.eg: Cl-, Br-, ClO4
-, NO3-, and I-
3. Any ion present on the KA table between strong acids & strong bases will hydrolyze. If it has no H+, you know it will act as a base.
eg: CO32-
(aq) + H2O(l) HCO3-(aq)
+ OH-(aq)
If it has H+, it is amphiprotic and you must determine whether it acts as an acid or a base.(compare its KA to its KB)
Note: NH4+ only acts as an acid.
HSO4- only acts as an acid.