(a) Write a balanced chemical equation for the formation of 1 mol of MgO (s) from the elements i

step 1 Okay, so in this question, they want us to write the balance reaction using elements in their st

(a) Write a balanced chemical equation for the formation of...

(a) Write a balanced chemical equation for the formation of 1 mol of $\mathrm{MgO}$ (s) from the elements in their standard states. (Find the value for $\Delta_{j} H^{\circ}$ for $\mathrm{MgO}(s)$ in Appendix $\mathrm{L}$ ) (b) What is the standard enthalpy change for the reaction of 2.5 mol of Mg with oxygen?

(a) Write a balanced chemical equation for the formation of 1 mol of $\mathrm{MgO}$ (s) from the elements in their standard states. (Find the value for $\Delta_{j} H^{\circ}$ for $\mathrm{MgO}(s)$ in Appendix $\mathrm{L}$ )
(b) What is the standard enthalpy change for the reaction of 2.5 mol of Mg with oxygen?

Key Concepts

Standard Enthalpy of Formation

The standard enthalpy of formation is defined as the heat change that occurs when one mole of a compound is formed from its constituent elements, each in their standard states. This value is an essential reference point in thermochemistry and is used to calculate reaction enthalpies via Hess’s Law. It allows for the prediction and calculation of energy changes in chemical reactions by providing a baseline from which relative energy changes can be determined.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction where the number of atoms for each element is the same on both the reactant and product sides. This ensures the conservation of mass and energy during the reaction. In formation reactions, the equation illustrates how elements in their standard states combine to form a compound, with appropriate stoichiometric coefficients detailing the proportions of reactants needed to yield one mole of product.

Standard State

The standard state of an element refers to its most stable physical form at 1 bar pressure and a specified temperature (usually 25 °C). For formation reactions, it is crucial to start with elements in their standard states, as the standard enthalpy of formation for compounds is defined based on these conditions. This concept provides consistency and comparability between different thermodynamic measurements.

Stoichiometry in Thermochemistry

Stoichiometry in thermochemistry involves using the mole ratios indicated by a balanced chemical equation to scale the energy changes (such as enthalpy change) for chemical reactions to different amounts of reactants or products. It is the method used to calculate the overall enthalpy change of a reaction when the amounts of substances involved are not exactly one mole, ensuring that the energy changes are proportional to the quantities of reactants used.

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