Solubility Rules - Lecture notes 5-7 PDF

Preview

Summary

Solubility Rules...

Description

Solubility Rules Compounds containing the following ions are mostly soluble +¿ ¿ ¿ Rb ¿ +¿ ,¿ ¿ +¿ , K ¿ +¿ , Na ¿ Li −¿ ¿ −¿ , C 2 H 3 O 2 ¿ NO3 −¿ ¿ −¿ , I ¿ −¿ , Br ¿ Cl

Exceptions None

None

When any of these ions pairs with

2+¿ , 2+¿ ,∨Pb¿ +¿ , Hg 2¿ Ag¿

the

compound is insoluble. 2−¿ SO 4¿

Compounds containing the following ions are mostly insoluble

2−¿ S¿ −¿ ¿ OH

2+¿ , 2+¿ ,∨Pb¿ ¿ 2−¿ 2+¿ , Hg 2 When SO ¿ pairs with ¿ 2+¿ , Ba 4 ¿ 2+¿ , Sr ¿ Ca insoluble. Exceptions

When either of these ions pairs with

the compound is

+¿ , +¿ NH 4¿ ¿ +¿ , Fr , ¿ + ¿ ,Cs ¿ +¿ , Rb the ¿ +¿,K ¿¿ Li ¿

compound is soluble. 2+¿ , 2+¿ ,∨Ba ¿ pairs with the compound is ¿ 2+¿ , Sr ¿ Ca slightly soluble. *

2−¿ When S¿

2+¿ , 2+¿ ,∨Ba¿ −¿ When OH ¿ pairs with ¿ 2+¿ , Sr ¿ Ca slightly soluble * 3−¿ 2−¿ , PO 4¿ CO 3¿ When either of these ions pairs with

the compound is

+¿ , +¿ NH 4¿ ¿ +¿ , Fr , ¿ +¿ ,Cs ¿ + ¿ , Rb the ¿ +¿ , K ¿ ¿ Li ¿

compound is soluble.

Common acids and bases: Acids (strong electrolytes) Formula Hydrochloric acid HCl HBr Hydrobromic acid HI Hydroiodic acid HClO3 Chloric acid HClO 4 Perchloric acid HNO3 Nitric acid H 2 SO 4 Sulfuric acid HC 2 H 3 O 2 Acetic acid *Note: Those that are not found in the list, are considered weak acids. Bases (strong bases) Formula Sodium hydroxide NaOH Lithium hydroxide LiOH Potassium hydroxide KOH RbOH Rubidium hydroxide CsOH Cesium hydroxide FrOH Francium hydroxide Be (OH )2 Beryllium hydroxide Mg(OH )2 Magnesium hydroxide Ca(OH )2 Calcium hydroxide Strontium hydroxide Sr (OH )2 Barium hydroxide Ba(OH )2 Ra(OH )2 Radium hydroxide *Note: Those that are not found in the list are considered weak bases.

Reminder: - Strong acids and bases dissociate completely into ions once dissolved in water; therefore, they are the ones that will be “alone” when trying to find the complete ionic equation and the net ionic equation. Different chemical reactions: 1. Acid-base reaction (Neutralization): a reaction that forms water, and typically salt. 

Note: The term “salt” does not refer to table salt (NaCl), it means any ionic compound whose cation comes from a base and whose anion comes from an acid.

Notice the pattern of acid and base reacting to form water and a salt: Acid + Base → Water+Salt HCl(aq )+ NaO H (aq) → NaCl(aq) + H 2 O (l) 2. Gas Evolution Reactions (metathesis): a reaction that occurs in solution and forms a gas as one of the products. Other gas evolution reactions form an intermediate product that then decomposes into a gas. For example: HCl(aq )+ NaHCO 3(aq ) → H 2 CO 3( aq) + NaCl( aq) → H 2 O( l) +CO 2(g )+ NaCl(aq)

Types of Compounds that undergo Gas Evolution Reaction: Reactant Type

Intermediate product

Sulfides

None

Gas Evolved H2S

Carbonates & Bicarbonates

H 2 CO 3

CO2

Sulfites & Bisulfites

H 2 SO 3

SO 2

Ammonium

NH 4 OH

NH 3

Equation for sulfide as a reactant:

2 H Cl(aq) + K 2 S (aq ) → H 2 S(aq) +2 K Cl (aq ) Equation for carbonates and bicarbonates as reactants: 2 H Cl(aq) +K 2 CO3 ( aq) → H 2 O( l) +C O2 ( g) +2 K Cl (aq ) Equation for sulfites & bisulfites as reactants: 2 H Cl(aq) +K 2 SO 3 ( aq) → H 2 O ( l) + S O 2( g) +2 K Cl(aq) Equation for ammonium as a reactant: NH 4 Cl (aq )+ K OH (aq ) → H 2 O (l )+ N H 3 ( g) +K Cl(aq) 3. Redox reactions (oxidation – reduction): Oxidation is loss of electrons by a substance, whereas reduction is the gain of electrons by a substance. a. Oxidation number: are used to keep track of electrons during chemical reactions and are assigned to atoms using specific rules. The oxidation of an element results in an increase in its oxidation number, whereas reduction is accompanied by a

decrease in oxidation number. (

1−¿ 1+¿ Cl(s )¿ ) ¿ 0 0 2 Na (s) +Cl 2(g) → 2 Na

A) For any atom in its elemental form, the oxidation number is always zero. B) For any monatomic ion, the oxidation number equals the ionic charge. +¿ Ex: K ¿

has an oxidation number of +1,

number of -2, and so forth. b. Oxidation of metals by Acids and Salts:

2−¿ S¿

has an oxidation

i. The reaction between a metal and either an acid or a metal conforms to the general pattern: a.

A +BX → AX + B

c. Combustion reactions: is a type of redox reaction. They are characterized by the reaction of a substance with

O 2 to form one or more oxygen-containing

compounds, often including water. This type of reaction is exothermic (they emit heat). Compounds containing carbon and hydrogen – or carbon, hydrogen and oxygen – always form carbon dioxide and water upon combustion.

Type of Reaction Synthesis or combination Decomposition Single – displacement Double – displacement (metathesis)

Generic Explanation A +B→ AB AB → A + B A +BC → AC + B AB +CD → AD + BC...