Refining petroleum involves cracking large hydrocarbon molecules into smaller, more volatile pieces. A simple example of hydrocarbon cracking is the gas-phase thermal decomposition of butane to give ethane and ethylene: (a) Write the equilibrium constant expressions for K_p and K_c.

Key Concepts

Equilibrium Constant (K)

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction. For gaseous reactions, K_p is expressed in terms of partial pressures, while K_c is based on molar concentrations. Understanding how to derive these constants is essential for analyzing chemical reactions, particularly in the context of cracking hydrocarbons.

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. This principle is crucial in refining processes, as it helps predict how changes in temperature, pressure, or concentration will affect the yield of products like ethane and ethylene during hydrocarbon cracking.

Thermal Decomposition

Thermal decomposition is a chemical reaction where a compound breaks down into simpler substances when heated. In the context of hydrocarbon cracking, butane decomposes into smaller hydrocarbons, such as ethane and ethylene, under high temperatures. Understanding this process is vital for optimizing conditions in petroleum refining to maximize the production of desired volatile compounds.