Acid spills are often neutralized with sodium carbonate or sodium hydrogen carbonate. For neutralization of acetic acid, the unbalanced equations are 112 CH3CO2H1l2 + Na2CO31s2 S CH3CO2Na1aq2 + CO21g2 + H2O1l2 122 CH3CO2H1l2 + NaHCO31s2 CH3CO2Na1aq2 + CO21g2 + H2O1l2 (c) How much heat in kilojoules is absorbed or liberated in each reaction? See Appendix B for standard heats of for- mation; ΔH°f = - 726.1 kJ>mol for CH3CO2 Na(aq).

Verified step by step guidance

1. First, write the balanced chemical equations for the neutralization reactions. For acetic acid with sodium carbonate: \(2 CH_3CO_2H + Na_2CO_3 \rightarrow 2 CH_3CO_2Na + CO_2 + H_2O\). For acetic acid with sodium hydrogen carbonate: \(CH_3CO_2H + NaHCO_3 \rightarrow CH_3CO_2Na + CO_2 + H_2O\).
2. Next, use the standard heats of formation (\(\Delta H^\circ_f\)) values from Appendix B for each reactant and product in the balanced equations. You will need the values for \(CH_3CO_2H\), \(Na_2CO_3\), \(NaHCO_3\), \(CH_3CO_2Na\), \(CO_2\), and \(H_2O\).
3. Calculate the total heat of formation for the reactants and the products for each reaction by multiplying the heat of formation of each substance by its coefficient in the balanced equation and summing these values.
4. Determine the heat of reaction (\(\Delta H\)) for each neutralization by subtracting the total heat of formation of the reactants from the total heat of formation of the products. Use the formula: \(\Delta H = \sum (\Delta H^\circ_f \text{ of products}) - \sum (\Delta H^\circ_f \text{ of reactants})\).
5. The result from step 4 will give you the heat absorbed or liberated in each reaction in kilojoules. A negative value indicates heat is liberated (exothermic reaction), and a positive value indicates heat is absorbed (endothermic reaction).

Key Concepts

Neutralization Reactions

Neutralization reactions occur when an acid reacts with a base to produce water and a salt. In this context, acetic acid (CH3CO2H) reacts with sodium carbonate (Na2CO3) or sodium hydrogen carbonate (NaHCO3) to form sodium acetate (CH3CO2Na), carbon dioxide (CO2), and water (H2O). Understanding the stoichiometry of these reactions is essential for calculating the heat changes involved.

Enthalpy Change (ΔH)

Enthalpy change (ΔH) is a measure of the heat absorbed or released during a chemical reaction at constant pressure. It is crucial for determining whether a reaction is exothermic (releases heat) or endothermic (absorbs heat). The standard enthalpy of formation (ΔH°f) values for the reactants and products are used to calculate the overall ΔH for the reaction, which is necessary for answering the question about heat changes.

Standard Heats of Formation

Standard heats of formation (ΔH°f) represent the change in enthalpy when one mole of a compound is formed from its elements in their standard states. These values are essential for calculating the enthalpy change of a reaction using Hess's law, which states that the total enthalpy change is the sum of the enthalpy changes for individual steps. In this case, the ΔH°f for sodium acetate is provided, allowing for the calculation of heat changes in the neutralization reactions.