How much heat in kilojoules is evolved or absorbed in the reaction of 2.50 g Fe2O3 with enough carbon monoxide to produce iron metal? Is the process exothermic or endothermic? Fe2O3(s) + 3 CO2(g) → 2 Fe(s) + 3 CO2(g) ΔH° = -24.8 kJ

Verified step by step guidance

1. Step 1: Determine the molar mass of Fe2O3. Calculate the molar mass by adding the atomic masses of 2 iron (Fe) atoms and 3 oxygen (O) atoms.
2. Step 2: Convert the mass of Fe2O3 to moles. Use the formula: moles = mass (g) / molar mass (g/mol).
3. Step 3: Use the stoichiometry of the balanced chemical equation to find the moles of Fe2O3 reacting. The balanced equation shows a 1:1 ratio between Fe2O3 and the reaction.
4. Step 4: Calculate the heat evolved or absorbed using the enthalpy change (ΔH°) of the reaction. Multiply the moles of Fe2O3 by the ΔH° value (-24.8 kJ/mol) to find the total heat change.
5. Step 5: Determine if the process is exothermic or endothermic. Since ΔH° is negative, the reaction is exothermic, meaning heat is evolved.

Key Concepts

Thermochemistry

Thermochemistry is the study of the heat energy associated with chemical reactions and phase changes. It involves understanding how energy is absorbed or released during these processes, which is quantified in terms of enthalpy (ΔH). In this context, the negative ΔH value indicates that the reaction releases heat, classifying it as exothermic.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on balanced chemical equations. It allows us to determine the amount of heat evolved or absorbed by relating the mass of reactants to the enthalpy change. In this case, we need to convert the mass of Fe2O3 to moles to find the corresponding heat change using the given ΔH.

Exothermic vs. Endothermic Reactions

Exothermic reactions release heat to the surroundings, resulting in a negative enthalpy change (ΔH < 0), while endothermic reactions absorb heat, leading to a positive ΔH. The classification of a reaction as exothermic or endothermic is crucial for understanding energy flow in chemical processes. In the provided reaction, the negative ΔH indicates that it is exothermic, meaning heat is evolved.