BackGeneral Chemistry: Essential Constants, Conversions, and Key Formulas
Study Guide - Smart Notes
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Conversions & Constants
Introduction
In General Chemistry, it is essential to be familiar with common physical constants and unit conversions. These are frequently used in calculations involving thermodynamics, kinetics, and other core topics.
Temperature Conversions:
°C = 5/9 (°F - 32)
K = °C + 273.15
Energy and Power:
1 W = 1 J/s
1 J = 1 kg·m2/s2
Gas and Thermodynamic Constants:
R = 0.08206 L·atm/K·mol = 8.314 J/K·mol
101.3 J = 1 L·atm
Key Formulas
Thermodynamics and Energy
These formulas are fundamental for understanding heat, work, and energy changes in chemical systems.
Heat Transfer:
Change in Internal Energy:
Work (at constant pressure):
Enthalpy Change per Mole:
Enthalpy of Reaction
Standard Enthalpy Change of Reaction:
Where:
= stoichiometric coefficient
= standard enthalpy of formation
Electrostatics and Kinetic Energy
Coulomb's Law (Electrostatic Energy):
Kinetic Energy:
Chemical Kinetics
Chemical kinetics deals with the rates of chemical reactions and the factors affecting them.
Rate Law for a Reaction A → B:
General Rate Law (for A and B as reactants):
Integrated Rate Laws
First-Order Reaction:
First-Order (Logarithmic Form):
Second-Order Reaction:
Arrhenius Equation
Temperature Dependence of Rate Constant:
Comparing Rate Constants at Two Temperatures:
Example Applications
Example 1: To convert 25°C to Kelvin:
Example 2: Calculating the enthalpy change for a reaction using standard enthalpies of formation.
Example 3: Using the Arrhenius equation to determine the effect of temperature on reaction rate.
