To calculate the standard enthalpy change for the reaction, we need to know the balanced chemical equation and the standard enthalpies of formation for each compound involved in the reaction. The balanced chemical equation for the reaction between Aquapentamminecobalt III chloride and sodium hydroxide is:Co NH3 5Cl3 aq + NaOH aq Co NH3 5 OH 3 s + NaCl aq Now, we need the standard enthalpies of formation Hf for each compound. Unfortunately, the standard enthalpies of formation for Aquapentamminecobalt III chloride and Aquapentamminecobalt III hydroxide are not readily available in literature or databases. However, if you were able to find or measure the standard enthalpies of formation for these compounds, you could calculate the standard enthalpy change for the reaction using the following equation:H = Hf products - Hf reactants Where H is the standard enthalpy change for the reaction, and Hf are the standard enthalpies of formation for the products and reactants.If you can provide the standard enthalpies of formation for the compounds involved, I would be happy to help you calculate the standard enthalpy change for the reaction.