The rate of a chemical reaction measures how quickly a reactant is consumed or a product is formed. It's expressed as the change in the amount of a reactant or product per unit time.
For a chemical reaction to occur:
A successful collision leads to a reaction. The rate of reaction increases with more successful collisions.
🔑 Key Concept: The minimum energy needed for a successful collision is called activation energy.
Increasing reactant concentration raises the frequency of collisions, speeding up the reaction.
Higher temperatures increase the kinetic energy of particles, leading to more frequent and energetic collisions, thus increasing the reaction rate.
Smaller solid particles have a larger surface area, allowing more collisions with other reactants, speeding up the reaction.
💡 Example: Powdered solids react faster than lumps.
Catalysts speed up reactions without being consumed. They lower the activation energy, increasing the frequency of successful collisions.
Different methods are used based on the reactants and products involved:
Use a gas syringe to measure the volume of gas released at regular intervals.
Monitor mass loss as reactants convert to products.
Measure how long it takes for a specific mass of reactant to fully react.
Measure the time taken to form a certain amount of product.
When gas is produced, use a gas syringe:
Definition: A reversible reaction is a chemical reaction where products can be converted back into reactants under suitable conditions.
Dehydration: Heating blue hydrated copper(II) sulfate:
(Blue crystals) → (White powder)
Hydration: Adding water to white anhydrous copper sulfate:
(White powder) → (Blue crystals)
Overall Reaction:
Definition: An irreversible reaction is a chemical reaction in which products cannot be converted back into reactants.
When calcium carbonate is heated, it decomposes:
The carbon dioxide escapes into the air, and the reaction cannot be reversed.
📚 Definition: Developed by Johannes Brønsted and Thomas Lowry, this theory defines acids and bases based on their ability to donate or accept protons (H⁺).
🔴 Acid: A proton donor
🔵 Base: A proton acceptor
When an acid dissolves in water, it donates protons (H⁺), which are accepted by water, resulting in the formation of hydronium ions (H₃O⁺).
🟡 Conjugate Acid: Formed when a base gains a proton.
🟢 Conjugate Base: Formed when an acid loses a proton.
📖 Definition: A conjugate acid-base pair consists of two species related by the gain or loss of a proton (H⁺).
Pairs: NH₄⁺/NH₃ and H₂O/OH⁻
Pairs: H₂SO₄/HSO₄⁻ and HNO₃⁺/HNO₃
Pairs: CH₃COOH/CH₃COO⁻ and H₃O⁺/H₂O
Completely ionize in water, producing many hydrogen ions.
Examples:
Partially ionize in water, producing fewer hydrogen ions.
Examples:
🔬 Concept: Acids and bases can conduct electricity due to ionization in water. Strong acids and bases have higher conductivity than weak ones because they ionize completely.
✅ Conclusion: The solution with the highest ammeter reading is the strong acid or base, while the one with the lowest reading is the weak acid or base.
Indicates how easily an acid or base ionizes to produce ions (hydrogen ions for acids, hydroxide ions for bases).
Refers to the proportion of solute (acid or base) in the solution compared to the solvent (water).
Oxides are compounds that contain oxygen and another element. They can be classified into three main types:
Formation: Produced when oxygen reacts with metals.
Examples:
Characteristics:
Formation: Produced when oxygen reacts with non-metals.
Examples:
Characteristics:
Characteristics: Have both acidic and basic properties.
Reactivity: React with both acids and bases to form salts and water.
Examples:
Maintaining appropriate pH levels is crucial for efficient functioning in various environments:
Salts are formed when the hydrogen ion of an acid is replaced by a metal or ammonium radical. Methods for preparing salts include:
Method: Titration is used for reactive metals like sodium or potassium.
Example:
Method: Used for less reactive metals (e.g., Mg, Zn).
Example:
Method: Any metal carbonate can react with an acid.
Example:
Method: For unreactive metals (e.g., Pb, Cu), neutralization occurs with metal oxides.
Example:
Method: Mixing two soluble solutions to form an insoluble salt.
Example:
✅ All potassium (K), sodium (Na), and ammonium (NH₄) salts are soluble.
✅ All nitrates and hydrogen carbonates are soluble.
⚠️ Most sulfates are soluble, except for lead (PbSO₄) and barium (BaSO₄); calcium sulfate (CaSO₄) is sparingly soluble.
⚠️ Most chlorides are soluble, except silver chloride (AgCl) and lead chloride (PbCl₂) (soluble only in hot water).
❌ Most carbonates are insoluble, except for those of potassium, sodium, and ammonium.
Process: Sodium carbonate is used to precipitate toxic cations as insoluble carbonates, which are then filtered out. It also softens hard water by precipitating hardness-causing ions.
Process: Precipitation is used to remove toxic ions from liquid wastes. Insoluble solids formed can be removed through sedimentation or filtration.
Use: Precipitation can help immobilize heavy metals in contaminated soils.
Example: Adding reagents to form insoluble compounds, preventing metal uptake by plants.
Use: Precipitation reactions are used to determine the concentration of specific ions in a solution.
Example: Silver nitrate can be added to a solution containing chloride ions to form a white precipitate of silver chloride.
Use: Precipitation reactions are employed in drug formulation and delivery.
Example: Forming insoluble drug compounds can control the release rate of medications in the body.