Types of Chemical Reactions Quiz

Study Notes

Types of Chemical Reactions

Synthesis (Combination) Reactions
- Two or more reactants combine to form one product.
- General form: A + B → AB
- Example: 2H₂ + O₂ → 2H₂O
Decomposition Reactions
- A single compound breaks down into two or more products.
- General form: AB → A + B
- Example: 2H₂O → 2H₂ + O₂
Single Replacement (Displacement) Reactions
- An element replaces a similar element in a compound.
- General form: A + BC → AC + B
- Example: Zn + CuSO₄ → ZnSO₄ + Cu
Double Replacement (Metathesis) Reactions
- The anions and cations of two different compounds switch places.
- General form: AB + CD → AD + CB
- Example: AgNO₃ + NaCl → AgCl + NaNO₃
Combustion Reactions
- A substance combines with oxygen, releasing energy, usually in the form of heat and light.
- Commonly involves hydrocarbons.
- Example: CH₄ + 2O₂ → CO₂ + 2H₂O

Energy Changes in Reactions

Exothermic Reactions
- Release energy (usually as heat).
- Energy of reactants > energy of products.
- Example: Combustion of fuels.
Endothermic Reactions
- Absorb energy from surroundings.
- Energy of reactants < energy of products.
- Example: Photosynthesis (6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂).
Activation Energy
- Minimum energy required to initiate a reaction.
- Influences the rate of reaction.
Reaction Mechanism
- Steps that constitute the overall reaction, involving a series of elementary reactions.

Equilibrium and Le Chatelier's Principle

Chemical Equilibrium
- A state in which the concentrations of reactants and products remain constant over time.
- Reactions in dynamic balance, with forward and reverse reactions occurring at equal rates.
Le Chatelier's Principle
- States that if a system at equilibrium is subjected to a change (concentration, temperature, pressure), the system adjusts to counteract the change and re-establish equilibrium.
- Key applications:
  - Concentration: Adding reactants shifts equilibrium toward products.
  - Temperature: Increasing temperature favors endothermic direction; decreasing favors exothermic direction.
  - Pressure: Increasing pressure favors the side with fewer moles of gas; decreases pressure favors more moles.
Equilibrium Constant (K)
- Ratio of the concentrations of products to reactants at equilibrium, each raised to the power of their coefficients.
- K > 1: Favors products.
- K < 1: Favors reactants.

Types of Chemical Reactions

Synthesis Reactions combine two or more reactants into a single product (A + B → AB). Example: 2H₂ + O₂ → 2H₂O.
Decomposition Reactions break down a single compound into two or more products (AB → A + B). Example: 2H₂O → 2H₂ + O₂.
Single Replacement Reactions involve an element replacing a similar element in a compound (A + BC → AC + B). Example: Zn + CuSO₄ → ZnSO₄ + Cu.
Double Replacement Reactions exchange anions and cations between two compounds (AB + CD → AD + CB). Example: AgNO₃ + NaCl → AgCl + NaNO₃.
Combustion Reactions involve a substance reacting with oxygen, releasing energy (usually as heat and light). Commonly involve hydrocarbons. Example: CH₄ + 2O₂ → CO₂ + 2H₂O.

Energy Changes in Reactions

Exothermic Reactions release energy (usually as heat) and have higher reactant energy than product energy. Example: Combustion of fuels.
Endothermic Reactions absorb energy from their surroundings and have lower reactant energy than product energy. Example: Photosynthesis (6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂).
Activation Energy is the minimum energy needed to initiate a reaction and influences the reaction rate.
Reaction Mechanism describes the steps involved in a reaction, usually consisting of a series of elementary reactions.

Equilibrium and Le Chatelier's Principle

Chemical Equilibrium is a state where reactant and product concentrations remain constant over time due to forward and reverse reactions occurring at equal rates.
Le Chatelier's Principle states that a system at equilibrium will adjust to counteract any applied change (concentration, temperature, pressure).
- Concentration: Adding reactants shifts equilibrium towards product formation.
- Temperature: Increasing temperature favors endothermic reactions, decreasing temperature favors exothermic reactions.
- Pressure: Increasing pressure favors the side with fewer gas moles, decreasing pressure favors the side with more gas moles.
Equilibrium Constant (K) measures the ratio of product to reactant concentrations at equilibrium, raised to their respective coefficients. K > 1 favors products, K < 1 favors reactants.

Description

Test your knowledge on the various types of chemical reactions, including synthesis, decomposition, single and double replacement, and combustion. Each reaction type has its unique characteristics and examples to help you understand the fundamental concepts of chemistry.