Chemical reactions are basically divided into two major classes depending on whether the reaction lose energy or gain energy from the environment during the course of the reaction. The two classes of reaction are exothermic and endothermic reaction.
An exothermic reaction is a type of reaction in which the reaction system lose energy to the environment and thus, the energy content of the reactants is more than that of the product formed. Because of this, the enthapyl change of an exothermic reaction is always negative.
An endothermic reaction is a type of reaction in which the reaction system absorb energy from the environment. Thus, the energy contents of the products is always higher than that of the reactants and the enthapyl change of the reaction is always positive. During the course of the reaction, the reaction container is usually cold to the touch because energy is been absorbed from the environment.
<h3><u>Answer;</u></h3>
D. It decreases and the pH increases.
<h3><u>Explanation;</u></h3>
- pH is a measure of the hydorgen ion concentration of a solution. Solutions with a high concentration of hydrogen ions have a low pH and solutions with a low concentrations of H+ ions have a high pH.
- <em><u>[H+] and [OH-] are inversely related. Therefore; As the concentration of H+ increases the pH decreases. Since the concentrations of H+ and OH- are inversely proportional, as one goes up, the other goes down. </u></em>
- <em><u>Therefore, an increase in OH- concentration will correspond to an increase in pH and a decrease in the concentration of H+.</u></em>
Lower the pH because increased number of free hydrogen ions
D. They act on a specific type of substrate in a reaction
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