CHEM-1411: Chapter 4 - Reactions in Aqueous Solution

Aqueous Reactions (aq)

Reactions often occur in a solvent, if the solvent is water, then it is an aqueous reaction

• Solvent

• Solute

• Homogenous v Heterogenous mixtures

• Electrolytes

• Non-electrolytes

Strong electrolyte

Dissociates completely when dissolved in water, The solution conducts electricity

Weak electrolyte

only dissociates partially when dissolved in water

Non-electrolyte

Does NOT dissociate in water. The solution does NOT conduct electricity

Concentration of ions in solution

The concentration of a solution tells you how much of the solute has been dissolved into the solution

It is given as mol/L, molarity

Precipitation Reactions

Occur when two solutions containing soluble salts are mixed and an insoluble salt is produced. The solids is called a precipitate

Soluble

dissolves into its parts

Insoluble

does NOT dissolve; “rocks”

Ionic Compounds

Metal - non-metal compound

Acids

• Are substances that ionize in aqueous solution to form H⁺, hydrogen ions

• Acids are often called proton donors

Bases

• Are substances that react with, or accept, H⁺ ions; they increase the concentrations of OH^-, hydroxide ions, when dissolved in water

• Substances do NOT have to contain OH^- to be a base, i.e. ammonia NH

Strength of Acids and Bases

• Strong acids and bases are completely ionize into their ions

• Weak acids and base partially ionize into their ions, they are at equilibrium

Neutralization Reactions

Reaction between an acid and a base

Gas Realease

When a carbonate or bicarbonate reacts with an acid, the products are a salt, carbon dioxide, and water

Dilution

• If we have a concentrated solution we can use that to create a more dilute solution in a dilution

• You must go from a concentrated solution to a less concentred solution

Tritation

is an analytical technique in which one can calculate the concentration of a solute in a soltuon

Oxidation-Reduction Reactions (Redox Reactions)

• Loss of electrons is oxidation

• Gain of electrons is reduction

• One cannot occur without the other

Oxidation Numbers (ON)

• The state is effectively how many electrons any given atom has gained or lost in a reaction

• For an atom in its elemental form, the ON is always a 0

Displacement Reactions

• The reactivity of a metal determines if a solid metal can be converted into a metal ion (Activity Series)

• A+BY → AY+B

  • Zn_(s)+HBr

  • Mn+Pb(NO₃)₂

The Activity Series

• Can be used to predict how 2 elements or ions will interact

• Any metal on the list can be oxidized by the ions of elements below

• Cu_(s)+2Ag⁺_(aq) → Cu²⁺_(aq)+2Ag_(s)