Acetylene (C₂H₂(g)) is used for welding because oxyacetylene is the hottest burning common fuel gas. Using standard enthalpies of formation, calculate the quantity of heat produced when 10 g of acetylene is completely combusted in air under standard conditions.

Key Concepts

Standard Enthalpy of Formation

The standard enthalpy of formation is the change in enthalpy when one mole of a compound is formed from its elements in their standard states. It is a crucial concept in thermodynamics, as it allows for the calculation of heat changes in chemical reactions, particularly combustion. Each substance has a specific enthalpy of formation value, which can be found in tables and is essential for determining the overall heat released or absorbed during a reaction.

Combustion Reaction

A combustion reaction is a chemical process in which a substance reacts rapidly with oxygen, producing heat and light. In the case of acetylene, the reaction with oxygen produces carbon dioxide and water. Understanding the stoichiometry of the combustion reaction is vital for calculating the amount of heat released, as it involves balancing the chemical equation and determining the moles of reactants and products involved.

Heat of Combustion

The heat of combustion is the amount of energy released when a substance is completely burned in oxygen. It is typically expressed in kilojoules per mole (kJ/mol) and is derived from the standard enthalpies of formation of the reactants and products. This value is essential for calculating the total heat produced during the combustion of a specific mass of a substance, such as acetylene, allowing for practical applications in fields like welding and energy production.