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Molarity
Preparing a solution
Dilution
Solubility rules
Complete & Net Ionic Equations
Colligative properties
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Heat Flow
Energy diagrams
Thermochemical equations
Heating/ Cooling curves
Specific Heat Capacity
Calorimetry
Hess's Law
Enthalpies of formation
Bond enthalpies
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Collision Theory
Rate Comparisons
Integrated Rate Law
Differential Rate Law
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Equilibrium
Equilibrium Expression
ICE Tables
Calculating K
K vs Q
Le Chatelier's Principle
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Definitions
Conjugate Acids & Base Pairs
Autoionization of water
pH Scale
Strong Acids/ Bases
Ka and Kb
Buffer
Titrations
Indicators
pH salts
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Entropy
Gibb's Free Energy
G and Temperature
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Oxidation numbers
Half Reactions
Balancing Redox reactions
Voltaic cells
Cell potential (standard conditions)
Cell potential (non-standard)
Electrolysis
Quantitative Electrochemistry
Heating & Cooling Curves
Related Examples and Practice Problems
Additional Worked Out Examples/ Practice
Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures
Separation techniques: Selected and explaining limitation of appropriate separation
Relating Properties to Composition: Predicting classification based on descriptive properties
and more …
Topic Summary & Highlights
and Help Videos
Core Concept
Heating and cooling curves show how the temperature of a substance changes as it absorbs or releases heat. These curves illustrate phase changes and the energy required to change a substance’s state (solid, liquid, or gas).
Key Components of Heating and Cooling Curves
Temperature Plateau (Flat Sections):
The flat portions of the curve represent phase changes where temperature remains constant.
Heat of Fusion ($\Delta H_{\text{fus}}$): The energy required for a solid to melt into a liquid (or for a liquid to freeze into a solid).
Heat of Vaporization ($\Delta H_{\text{vap}}$): The energy required for a liquid to vaporize into a gas (or for a gas to condense into a liquid).
Sloped Sections:
The sloped portions represent temperature changes within a single phase (solid, liquid, or gas).
During these segments, the substance’s temperature changes as it absorbs or loses heat, but it doesn’t change phase.
Phase Changes:
Melting: Transition from solid to liquid.
Freezing: Transition from liquid to solid.
Vaporization: Transition from liquid to gas.
Condensation: Transition from gas to liquid.
Specific Heat (c):
The amount of heat needed to raise the temperature of 1 gram of a substance by 1°C (for each phase).
Different phases of a substance have different specific heat values.
Interpreting a Heating Curve
A typical heating curve for water (as an example) consists of the following steps:
Solid Phase (Heating Ice):
Temperature increases as heat is added, but the substance remains in the solid phase.
Heat Calculation: $q = m \cdot c_{\text{solid}} \cdot \Delta T$
Melting (Ice to Liquid Water):
Temperature remains constant as ice melts to liquid water. The added energy goes into breaking intermolecular forces rather than raising temperature.
Heat Calculation: $q = m \cdot \Delta H_{\text{fus}}$
Liquid Phase (Heating Water):
Temperature increases as liquid water absorbs heat.
Heat Calculation: $q = m \cdot c_{\text{liquid}} \cdot \Delta T$
Vaporization (Liquid to Gas):
Temperature remains constant as liquid water vaporizes to steam. The heat added overcomes intermolecular forces to separate molecules into the gas phase.
Heat Calculation: $q = m \cdot \Delta H_{\text{vap}}$
Gas Phase (Heating Steam):
Temperature increases as steam absorbs heat.
Heat Calculation: $q = m \cdot c_{\text{gas}} \cdot \Delta T$
Tips for Solving Heating and Cooling Curve Problems
Separate Each Phase: Calculate the heat required for each phase change and temperature change separately.
Use Correct Specific Heat and Heat of Phase Change: Ensure that you use the specific heat or enthalpy value appropriate for each phase (solid, liquid, or gas).
Double-Check Units: Convert all masses to grams, temperatures to Celsius or Kelvin as needed, and energy to joules or calories.
Add Heat Values: For total energy calculations, sum all heat values for each phase change and temperature segment.
