Thermodynamics & Rates

Mehr dazu

Biology 311C Extra Credit

von John Flores

The boy who tamed the wind

von Joffre Veloz

Carb Concept Cards

von lolo lolo

Affordable and Clean Energy

von Carolina Antonchuk

Thermodynamics & Rates

Enthalpy (ΔH)

Thermochemical Equations: Represent reactions with ΔH

Molar Enthalpy (ΔH/m): Heat change per mole of substance

Heat Transfer

ΔT: Change in temperature (°C)

c: Specific heat capacity (J/g°C)

m: Mass of substance (grams, g)

Q: Heat energy (Joules, J)

Equation: Q = mcΔT

Calorimetry

Calculate heat (Q) using Q = mcΔT

Measure temperature change (ΔT)

Mix reactants in the calorimeter

Procedure:

Types of Calorimeters: Coffee cup (constant pressure), bomb (constant volume)

Purpose: Measure heat absorbed or released during a chemical reaction

Factors Affecting Rates

Concentration: Higher concentration increases reaction rate

Catalysts: Lower activation energy, increase reaction rate

Surface Area: Greater surface area increases reaction rate

Temperature: Higher temperature increases reaction rate

Calculating Reaction Rates

Conductivity: Change in ionic concentration over time

pH: Change in acidity over time

Volume: Change in gas volume over time

Mass: Change in mass over time

Instantaneous Rate: Rate at a specific moment

Average Rate: Change in concentration over time

Hess' Law

Subtopic

Application: Combine steps to find overall ΔH

Principle: Total enthalpy change is the same regardless of the route taken

Energy Changes in Reactions

Energy Diagrams: Show energy changes during reactions

Endothermic Reactions: Net absorption of energy (e.g., photosynthesis)

Exothermic Reactions: Net release of energy (e.g., combustion)

Bond Breaking: Requires energy (endothermic)

Bond Formation: Releases energy (exothermic)