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Rewrite equations using ΔH notation per mole of a given reactant or product

Grade 10 SABIS

When rewriting equations using ΔH notation, we express the enthalpy change (ΔH) per mole of a given reactant or product. This notation allows us to specify the heat energy associated with a specific amount of substance participating in a reaction and provides a standardized way to compare the energy changes between different reactions.

To rewrite an equation using ΔH notation, we first determine the ΔH value for the reaction as it is originally written. This value represents the total enthalpy change for the entire reaction, typically measured in kilojoules (kJ) per mole of reaction.

Next, we identify the reactant or product for which we want to express the ΔH notation per mole. This could be any substance involved in the reaction, and we focus on that particular component to calculate the ΔH value per mole.

To express the ΔH notation per mole of the given reactant or product, we divide the total ΔH value by the stoichiometric coefficient of the reactant or product in the balanced chemical equation. This division accounts for the molar ratio between the reactant or product of interest and the overall reaction.

For example, let's consider the reaction: 2H2(g) + O2(g) → 2H2O(g) ΔH = -483.6 kJ

If we want to express the ΔH notation per mole of oxygen (O2), we divide the total ΔH value (-483.6 kJ) by the coefficient of O2 in the balanced equation, which is 1. This gives us ΔH = -483.6 kJ/mol O2.

Similarly, if we want to express the ΔH notation per mole of water (H2O), we divide the total ΔH value by the coefficient of H2O, which is also 1 in this case. Thus, ΔH = -483.6 kJ/mol H2O.

It's important to note that ΔH notation per mole allows for easy comparison of energy changes between reactions involving different amounts of substances. By normalizing the enthalpy change to a per-mole basis, we can directly compare the energy transformations associated with different reactions.

By using ΔH notation per mole, we can assess the heat energy involved in specific reactants or products and understand their individual contributions to the overall energy change in a reaction. This notation provides a standardized and convenient way to express and analyze energy changes in chemical reactions.

In summary, when rewriting equations using ΔH notation per mole of a given reactant or product, we divide the total ΔH value by the stoichiometric coefficient of the component of interest. This allows us to express the enthalpy change per mole and facilitates comparisons between reactions. ΔH notation per mole provides a standardized approach to quantifying the energy changes associated with specific reactants or products in chemical reactions.



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