Chemical Reactions and Mass Balance

Mass Balance

• Law of Conservation of Mass: Matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.
• Mass Balance Equation: Input (reactants) = Output (products) + Accumulation (in a closed system)
• Applications: Useful in designing and optimizing chemical reactions, reactors, and processes.

Chemical Reactions

• Chemical Equation: A symbolic representation of a chemical reaction, where reactants are on the left and products are on the right.
• Reactants: Substances that undergo a chemical change to form products.
• Products: Substances formed as a result of a chemical reaction.
• Stoichiometry: The study of the quantitative relationships between reactants and products in a chemical reaction.

Lavoisier's Contributions

• Antoine Lavoisier: A French chemist who discovered the role of oxygen in combustion and respiration.
• Oxygen's Role: Lavoisier showed that oxygen is necessary for combustion and respiration, and that it supports life.
• Calorimeter: Lavoisier developed an apparatus to measure heat changes during chemical reactions, laying the foundation for thermochemistry.
• Modern Chemical Nomenclature: Lavoisier developed a systematic method for naming chemical compounds, which is still in use today.

Mass Balance

• Matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.
• The mass balance equation states that input (reactants) equals output (products) plus accumulation (in a closed system).
• Mass balance is useful in designing and optimizing chemical reactions, reactors, and processes.

Chemical Reactions

• A chemical equation is a symbolic representation of a chemical reaction, with reactants on the left and products on the right.
• Reactants are substances that undergo a chemical change to form products.
• Products are substances formed as a result of a chemical reaction.
• Stoichiometry is the study of the quantitative relationships between reactants and products in a chemical reaction.

Lavoisier's Contributions

• Antoine Lavoisier was a French chemist who discovered the role of oxygen in combustion and respiration.
• Oxygen is necessary for combustion and respiration, and it supports life.
• Lavoisier developed a calorimeter to measure heat changes during chemical reactions, laying the foundation for thermochemistry.
• Lavoisier developed a systematic method for naming chemical compounds, which is still in use today, known as modern chemical nomenclature.

Reaction Rates

• Increasing concentration of reactants increases reaction rate due to more collisions between molecules
• Raising temperature increases reaction rate by providing more kinetic energy for molecules to collide effectively
• Increasing surface area of reactants increases reaction rate by providing more sites for collisions to occur
• Presence of catalysts increases reaction rate by lowering activation energy

Collision Theory

• Reactant molecules must collide with sufficient energy and correct orientation for reaction to occur
• Increasing temperature increases kinetic energy, allowing more successful collisions to occur

Activation Energy

• Energy barrier that must be overcome for reaction to occur
• Raising temperature provides more energy for reactants to overcome activation energy, increasing reaction rate

Equilibrium

• State in which forward and reverse reactions occur at equal rates, with no net change in concentrations of reactants and products
• Equilibrium constant (K) is the ratio of concentrations of products to reactants at equilibrium
• Equilibrium constant (K) depends on temperature, but not on initial concentrations

Le Chatelier's Principle

• If a system at equilibrium is subjected to a change, the equilibrium will shift to counteract the change
• Examples of changes that can affect equilibrium include changes in concentration, temperature, or pressure

Catalysts

• Definition: a substance that increases reaction rate without being consumed or altered
• Catalysts work by lowering activation energy, allowing more molecules to react
• Homogeneous catalysts are present in the same phase as reactants, while heterogeneous catalysts are present in a different phase
• Characteristics of catalysts include high surface area, high reactivity, and remaining unchanged after reaction
• Examples of catalysts include enzymes in biological reactions and metals in industrial processes

Reaction Rates

• Reaction rate is the speed at which a chemical reaction occurs, and it is affected by several factors, including:
  • Concentration of reactants, which increases reaction rate when increased
  • Temperature, which increases reaction rate when increased
  • Surface area of reactants, which increases reaction rate when increased
  • Presence of catalysts, which increases reaction rate
• Rate equation is a mathematical expression that describes the rate of a reaction, typically expressed in terms of concentration of reactants and products, and may include rate constants and order of reaction.

Catalysts

• A catalyst is a substance that increases the rate of a chemical reaction without being consumed or altered in the process, and it has the following characteristics:
  • Not consumed or altered during the reaction
  • Increases reaction rate
  • Lowers activation energy
  • Can be reused
• There are two types of catalysts:
  • Homogeneous catalysts, which are present in the same phase as the reactants
  • Heterogeneous catalysts, which are present in a different phase than the reactants
• Examples of catalysts include:
  • Enzymes in biological reactions
  • Metals in industrial reactions

Equilibrium Constants

• Equilibrium constant (K) is a value that describes the ratio of the concentrations of products to reactants at equilibrium, and it has the following characteristics:
  • Independent of initial concentrations
  • Dependent on temperature
  • Related to the Gibbs free energy change (ΔG) of the reaction
• There are two types of equilibrium constants:
  • Kc, which is the equilibrium constant in terms of concentration
  • Kp, which is the equilibrium constant in terms of pressure
• Importance of equilibrium constants lies in their ability to:
  • Predict the direction of a reaction
  • Determine the extent of a reaction
  • Relate to the spontaneity of a reaction

Understand the concept of mass balance and its application in chemical reactions, including the law of conservation of mass and mass balance equations.