4.1 General Properties of Aqueous Solutions

• A solution is a mixture of two or more components that is homogenous.

  • The solute is the substance that is present in lesser quantities.

  • The solvent is the material that is present in greater quantities.

  • Aqueous solutions are those in which the solute is a liquid or solid at first, and the solvent is water.

• There are two types of solutes that dissolve in water: electrolytes and nonelectrolytes.

  • An electrolyte is a material that, when dissolved in water, produces an electrically conductive solution.

  • When dissolved in water, a nonelectrolyte does not conduct electricity.

4.2 Precipitation Reactions

• The precipitation reaction, which results in the creation of an insoluble product known as a precipitate, is a typical type of reaction that happens in an aqueous solution.

  • A precipitate is a solid that separates from a solution because it is insoluble.

  • Ionic chemicals are used in most precipitation reactions.

• A metathesis reaction is a reaction in which portions of two substances are exchanged.

• It is determined by the solute's solubility, which is defined as the greatest amount of solute that may dissolve in a given amount of solvent at a particular temperature.

4.3 Acid-Base Reactions

• The definitions of acids and bases given by Arrhenius are limited in that they only apply to aqueous solutions.

  • A proton donor is a Bronsted acid.

  • A proton acceptor is a Bronsted base.

  • The hydronium ion is the hydrated proton, H3O+(aq).

• The reaction in which a Brnsted acid (HCl) contributes a proton to a Brnsted base is depicted in this equation (H2O).

• Hydrochloric acid (HCl), nitric acid (HNO3), acetic acid (CH3COOH), sulfuric acid (H2SO4), and phosphoric acid are some of the most regularly utilized acids in laboratories (H3PO4).

  • The first three are monoprotic acids, which means that when ionized, each unit of the acid generates one hydrogen ion.

• Because each unit of sulfuric acid (H2SO4) releases two H+ ions, it is a diprotic acid.

• Tricrotic acids, which produce three hydrogen ions, are uncommon.

  • Phosphoric acid is the most well-known tricrotic acid.

4.4 Oxidation-Reduction Reactions

• While acid-base reactions are proton-transfer events, oxidation-reduction reactions, or redox reactions, are electron-transfer reactions.

• A half-reaction that illustrates the electrons involved in a redox reaction in detail.

  • The half-reaction that involves the loss of electrons is referred to as an oxidation reaction.

  • A reduction reaction is a half-reaction in which electrons are gained.

  • Magnesium is oxidized during the production of magnesium oxide. It's called a reducing agent because it transfers electrons to oxygen, causing it to be reduced.

  • Because it receives electrons from magnesium, oxygen is reduced and functions as an oxidizing agent, causing magnesium to be oxidized.

• It's helpful to give oxidation numbers to the reactants and products to keep track of electrons in redox processes.

• The oxidation number, commonly known as the oxidation state, of an atom, indicates how many charges it would have in a molecule if electrons were transported.

• Combination, decomposition, combustion, and displacement reactions are some of the most prevalent oxidation-reduction reactions.

  • A combination reaction occurs when two or more chemicals react to produce a single result.

  • The reaction of decomposition is the polar opposite of the reaction of combination.

  • A decomposition reaction occurs when a chemical is broken down into two or more components.

  • A combustion reaction occurs when a chemical combines with oxygen, usually releasing heat and light in the form of a flame.

  • An ion of a compound is replaced by an ion of another element in a displacement reaction

• In a disproportionation process, an element in one oxidation state gets oxidized and reduced at the same time.

4.5 Concentration of Solutions

• The amount of solute present in a given amount of solvent, or a given amount of solution, is referred to as the concentration of a solution.

• Molarity (M), also known as molar concentration, is the number of moles of solute per liter of solution and is one of the most often used units in chemistry.

  • Where n is the number of moles of solute and V denotes the volume of the solution in liters, molarity is defined.

4.6 Gravimetric Analysis

• Gravimetric analysis is a technique for analyzing data based on mass measurements.

• First, an unknown-composition sample ingredient is dissolved in water and allowed to react with another component to generate a precipitate.

  • The precipitate is filtered, dried, and weighed after that.

• We can compute the mass of a specific chemical composition of the original sample using the mass and chemical formula of the precipitate created.

• Finally, we may calculate the percent composition by mass of the component in the original compound using the mass of the component and the mass of the original sample.

4.7 Acid-Base Titrations

• Titration is the most convenient method for conducting quantitative research of acid-base neutralization processes.

  • In a titration, a solution with an exact concentration, known as a standard solution, is gradually added to another solution with an unknown concentration until the chemical reaction between the two solutions is complete.

• A sudden change in the color of an indicator in the acid solution usually indicates the equivalence point.

  • The point at which the acid has completely interacted with or been neutralized by the base is called the equivalence point.

  • The indicators in acid-base titrations are compounds that have distinct hues in acidic and basic environments.

4.8 Redox Titrations

• The transfer of electrons occurs in redox reactions, while the transfer of protons occurs in acid-base reactions.

• We can titrate an oxidizing agent against a reducing agent in the same way that we can titrate an acid against a base.

  • When the reducing agent is oxidized by the oxidizing agent, the equivalence point is reached.

• Because they have distinct hues in their oxidized and reduced forms, oxidizing agents can be utilized as an internal indicator in redox titration.

  • Acid-base neutralization require the same type of calculations as redox titrations.