The addition of 3.15 g of \(\mathrm{Ba}(\mathrm{OH})_{2} \cdot 8 \mathrm{H}_{2} \mathrm{O}\) to a solution of \(1.52 \mathrm{g}\) of \(\mathrm{NH}_{4} \mathrm{SCN}\) in \(100 \mathrm{g}\) of water in a calorimeter caused the temperature to fall by \(3.1^{\circ} \mathrm{C} .\) Assuming the specific heat of the solution and products is \(4.20 \mathrm{J} / \mathrm{g}^{\circ} \mathrm{C}\) calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation: $$\mathrm{Ba}(\mathrm{OH})_{2} \cdot 8 \mathrm{H}_{2} \mathrm{O}(s)+2 \mathrm{NH}_{4} \mathrm{SCN}(a q) \longrightarrow \mathrm{Ba}(\mathrm{SCN})_{2}(a q)+2 \mathrm{NH}_{3}(a q)+10 \mathrm{H}_{2} \mathrm{O}(I)$$

Calorimetry is an experimental technique that allows us to measure the amount of heat involved in a chemical or physical process. By using a device known as a calorimeter, scientists can track temperature changes in a substance as it undergoes a reaction. This temperature change, when carefully measured, corresponds to the heat absorbed or released during the process.

During a calorimetry experiment, such as the one described in the exercise, the change in temperature of the water solution helps us determine the heat exchange involved in the dissolution and chemical reaction. The experiment took place in a calorimeter, which helped to isolate the system and better measure the temperature changes and therefore the heat involved.

Enthalpy change, often symbolized as \( \Delta H \), embodies the total heat content change within a system at constant pressure. This key term in thermochemistry signifies whether a reaction is exothermic (releases heat) or endothermic (absorbs heat).

In this case, since the temperature decreases, we can conclude that the reaction is endothermic—the heat is absorbed by the reaction from the surrounding water. The enthalpy change is a crucial piece of information about a reaction's energy dynamics and can inform us about the stability of the products relative to the reactants.

The specific heat capacity (\( c \) is a physical property of materials that describes how much heat energy is required to raise the temperature of one gram of a substance by one degree Celsius. Its units are typically \( \text{J/g}^\circ \text{C} \).

Understanding the specific heat capacity is vital because it tells us how a substance behaves when exchanging heat. In the exercise, the specific heat capacity of the solution and products (\(4.20 \text{J/g}^\circ \text{C}\)) is provided. It helps to calculate the total heat absorbed by the aqueous solution when the temperature of the system decreases, which enables us to solve for the heat absorbed in the reaction.

Chemical reactions, such as the one given in the exercise, involve the breaking and forming of chemical bonds, resulting in new substances. These reactions can be characterized by energy changes, which are often observed as changes in temperature.

Understanding the nature of chemical reactions enables us to predict the energy exchange, reactants' and products' stability, and the spontaneity of the reactions. In the given equation, the combination of \(\mathrm{Ba}(\mathrm{OH})_2 \cdot 8 \mathrm{H}_2\mathrm{O}\) and \(\mathrm{NH}_4\mathrm{SCN}\) results in new products and a net absorption of heat, as demonstrated by the decrease in temperature measured in the calorimetric experiment.