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Unit 2: Thermodynamics and Rates of Reactions - Coggle Diagram
Unit 2: Thermodynamics and Rates of Reactions
Systems- Part of the universe that's being studied
Closed System - No Matter can move but energy can transfer between system and surroundings
Open System- Energy and Matter can Move between Surroundings and system
Isolated system - No matter and no energy can move between system and surroundings
Enthalpy - How much energy something has - AKA Heat content
Types of Enthalpies- Potential and Kinetic
Enthalpy Change- How much energy is absorbed or released from a system. (ΔH = q)
Thermochemical Equations show how much energy is absorbed or emitted in a chemical reaction
Exothermic: Energy is released from the system to the surroundings.
Endothermic: Energy is absorbed from the system to the surroundings.
Connection to Unit 4: Equilibrium. If you apply heat to either of those reactions when the equilibrium would shift (Le Chatelier's Principle). If you apply energy to an Exothermic reaction the reaction would shift to the reactants, if you apply energy to an Endothermic reaction the reaction would shift to the products. This then shows that the Haber Process is an Exothermic reaction because taking energy away (Lowering temperature) Favors the products side.
Calculating Enthalpy Change
Bond Energy Method
Based on the energy of breaking and forming bonds
Calorimetry Method
Based off experimental results with enthalpy change
Reactions held in a Calorimeter
Assuming it's an isolated system, all aqueous solutions have the same heat capacity as water
Hess's Law
Additivity Method
identify step equations and put them with the list
Place them all together and balance all out to cancel all intermediates
Calculate Enthalpy change by adding all changes
Connection to Unit 5 Redox.
Finding Cell Potential (E) and Finding the enthalpy change (ΔH) require very similar steps such as stacking equations and reversing some to get a desired number
Summation Method
Subtract the enthalpy change of the formation of products by the formation of reactants
Rates of a reaction - How fast a reaction occurs, measured by seeing how much reactant is being consumed over a period of time, can be measured through Volume, mass, color, pressure.
As time goes by, less product is produced over time, less reactant is consumed
Connection to Unit 4 Equilibrium, you can see on the concentration time graph that the concentration of product and the concentration of reactant remain constant after reaching a point. That point is known as equilibrium
Reaction Mechanisms
To find the rate of the reaction you need to find the rate determining step AKA slow step AKA the step that requires most energy
Molecularity- Most common types of reactions occur with 1 or 2 reactants
Reaction Intermediates - Created in the steps but formed in the net equation
Rate Law Expression: r = k(A)^a(B)^b
Maxwell-Boltzmann Distribution
shows the number of molecules that have a certain energy, this means that reactions that require energy to begin could start. (Eg: Boiling water)
Collision Theory - A product of a reaction can only be created when the reactants hit each other in the correct way and with enough energy
Connection to Unit 3: Organic Chemistry. The substitution reaction in Organic Chemistry actually has many side products based on how the reactants collide. This actually shows the Collision theory in action as different orientations lead to different reactions and not always the same product (Propagation steps, Termination Steps)
Also Applies to endothermic Reactions, we need to add energy for the reaction to happen, which means there wasn't enough on it's own for the reaction to occur
