Thermochemistry+2c+-+Calorimetry
Unit 1: Thermochemistry Overview
Focus on the determination of enthalpy changes during chemical reactions using calorimetry; formulae and principles are discussed throughout.
Page 1: Introduction to Calorimetry
Fundamental understanding of calorimetry.
Key Goal: Use calorimetry data to determine enthalpy changes in reactions.
Page 2: Calorimetry Video
Subject Matter Expert: Dr. Paul McCord
Emphasizes the importance of calorimetry in understanding thermochemistry.
Page 3: Principles of Calorimetry
Heat Exchange Principles:
Heat Lost = - Heat Gained
Heat gained by surroundings equals heat lost by system and vice versa.
Classifications:
Exothermic: Releases heat.
Endothermic: Absorbs heat.
Page 4: Equipment Used in Calorimetry
Key Components:
Styrofoam lid and calorimeter.
Reaction mixture and temperature sensor relevant to heat measurement.
Page 5: Calorimetry Functionality
Quantitative measurement of energy changes.
An isolated system that prevents energy or matter transfer is essential.
A calorimeter approximates isolation, measuring heat changes of physical or chemical processes.
Page 6: Assumptions in Calorimetry
System isolation assumption ensures negligible energy loss.
Assumption of minimal thermal exchange with calorimeter materials (Styrofoam cups, thermometer, etc.).
Reaction in water maintains the properties of water (specific heat capacity and density).
Constant pressure maintained during reactions.
Page 7: Kinetic Energy Calculation
Heating Methodology: Estimates using:
Amount of water (m), specific heat capacity (c), initial and final temperature (ΔT).
Formula: q = mcΔT
Potential Energy:
ΔrHm = nΔrHm for combustion reactions (e.g., burning potato chip).
Page 8: Key Equations for Calorimetry
Heat Transferred Equation:
q = mcΔt
where q = heat transferred, m = mass of water, c = specific heat capacity, Δt = temperature change.
Reaction-based heat transferred:
q = nΔrHm
where n = moles of fuel and ΔrHm = molar enthalpy of reaction.
Relationship:
nΔrHm = -mcΔt
Page 9 & 10: Importance of Insulation in Calorimetry
Insulation Requirement:
Calorimeters must insulate reactions to minimize heat loss to the environment.
Utilizes measured mass, specific heat, and temperature change for calculations.
For burning potato chips and similar substances, establishing moles helps compute heat changes.
Page 11: Decision Making for Equations
Different formulas based on specific situations:
q = mcΔT and q = -ΔrH.
ΔrH = nΔrHm; combine relations to maintain equilibrium.
Page 12: POGIL (Process Oriented Guided Inquiry Learning)
Introduces collaborative and inquiry-based analysis in learning thermochemistry.
Page 13: Example Problem on Combustion of Methane
Example data: Combustion of 5.00 g of methane; calculation of resulting temperature change in heated water.
Moles of methane derived from its mass (molar mass: 16.05 g/mol).
Formula application to find temperature change (ΔT):
Using the combustion molar enthalpy: ΔrHm = -803.0 kJ/mol.
Page 14: Continued Calculations for Temperature Change
Deriving Δt using the relationship between water mass and energy lost to the water.
Outcome: Δt calculated to be 11.9 ºC.
Page 15: Energy Gained by Water from Reaction
Energy gained calculated: ΔrH = 249 kJ using mass of water and specific heat.
Page 16: Energy Released by Reaction
Energy released through reaction calculations: ΔrH = –250 kJ.
Page 17: Molar Enthalpy of Reaction for Nitrogen Gas
Calculation for nitrogen reacted with oxygen provides molar enthalpy information for synthesizing nitrogen monoxide.
Further calculations to estimate result in kJ/mol.
Page 18: Learning Insights
Notable Quotes to encourage and reflect on insights gained through learning and analysis.
Page 19: Diploma Exam Preparation
Practical calculation of energy transferred during a reaction between ammonium nitrate and water.
Final outcome of ΔrHm provided.
Page 20: Assignment Overview
Assignment addressed: Posing questions and reviewing key concepts crucial for comprehension.
Page 21: Guided Practice Exercise 1
Neutralization reaction for sulfuric acid with potassium hydroxide in calorimeter setup.
Calculation of molar enthalpy of neutralization based on temperature change.
Page 22: Guided Practice Exercise 2
Assessment of copper oxidation reaction in a calorimeter.
Specification of mass, heat change, and final energy calculations mentioned.
Page 23: Guided Practice Exercise 3
Calculation involving zinc reaction with hydrochloric acid; qualitatively assess energy released and required mass of zinc for a defined temperature increase.