How to Calculate Reaction Enthalpy and Standard Enthalpy of Formation
How do you calculate reaction enthalpy for a given chemical reaction?
Calculate the reaction enthalpy for the following reaction: C(s) + O2(g) → CO2(g) given δHrxn = -394 kJ mol–1.
What is the standard enthalpy of formation and how is it estimated?
Estimate the standard enthalpy of formation of CO2(g) at 298 K using the given data.
Calculating Reaction Enthalpy
For the given chemical reaction C(s) + O2(g) → CO2(g) with δHrxn = -394 kJ mol–1, the reaction enthalpy is -394 kJ mol–1. This value represents the heat released or absorbed during the reaction under constant pressure conditions.
Estimating Standard Enthalpy of Formation
The standard enthalpy of formation (ΔHf°) of a compound is the change in enthalpy when 1 mole of the compound is formed from its elements in their standard states. To estimate the standard enthalpy of formation of CO2(g) at 298 K, we can use the given reaction enthalpy and other relevant data.
In order to calculate the reaction enthalpy, you simply need to consider the difference in enthalpy between the products and the reactants. In the case of C(s) + O2(g) → CO2(g) with a reaction enthalpy of -394 kJ mol–1, the negative sign indicates that the reaction is exothermic, meaning it releases energy in the form of heat.
Estimating the standard enthalpy of formation involves considering the enthalpies of the reactants and products in their standard states and using the given data. In this case, additional information such as the standard enthalpies of formation for the elements and compounds involved would be needed to accurately calculate the standard enthalpy of formation for CO2(g) at 298 K.