Lecture 3: Thermodynamics and Thermochemistry

These flashcards cover key concepts from Lecture 3 on thermodynamics and thermochemistry, including definitions of terms and principles relevant to the study of heat and energy in chemical reactions.

Enthalpy (H)

An extensive property of a substance used to obtain the heat absorbed or evolved in a chemical reaction at constant pressure.

State Variables

Variables characterizing the state of a system, which include intensive and extensive properties.

Intensive Properties

Properties that do not depend on the amount of substance, such as pressure (P) and temperature (T).

Extensive Properties

Properties that depend on the amount of substance, such as mass (m), volume (V), and amount of substance (n).

Thermochemical Equation

A balanced chemical equation that includes the enthalpy change (ΔH) for the reaction.

Significant Figures

Digits that indicate the precision of a measurement and the accuracy of calculated values.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed or transferred.

Molar Enthalpy

The heat content per mole of a substance, often used in stoichiometric calculations.

Scientific Notation

A way of expressing numbers as a coefficient multiplied by a power of 10, useful for very large or small quantities.

Order of Magnitude

A classification of quantities based on their scale, indicating the power of ten that is closest to that number.

Calorimetry

The measurement of heat transfer during chemical reactions or physical changes.

Unit Conversion

The process of changing one set of measurement units to another to ensure comparability and accuracy.

Heat of Reaction (ΔHRxn)

The change in enthalpy during a chemical reaction, calculated as the difference between the enthalpy of products and reactants.

Sources of Uncertainty

Factors that introduce error into measurements, including model errors, statistical variations, and instrumentation errors.

Combustion

A chemical reaction that typically releases heat by burning a fuel in the presence of oxygen.