In this video, we're going to introduce acids. Acids are any chemical that increases a solution's concentration of hydrogen ions, or H+ ions. Recall that the concentration of hydrogen ions can be abbreviated with brackets like this: [H+]. Whenever we see the brackets in science, it means the concentration of what's between the brackets. So, this is the concentration of hydrogen ions. Acids will increase the concentration of hydrogen ions in solution.
Let's take a look at our example below: the addition of hydrochloric acid, or HCl, to water. Notice on the far left, we're showing you four different molecules of hydrochloric acid. As its name implies, hydrochloric acid is an acid, meaning that when added to water, it increases the concentration of hydrogen ions. When a hydrochloric acid molecule is added to water, it splits into two components. It splits into a hydrogen ion, and into a chloride anion; the H+ and Cl-, respectively, from each HCl molecule when added into pure water.
In the beaker, we have these chloride anions, three of four of them, since we have four HCl molecules, and we also have four hydrogen ions. Ultimately, we can see that through the addition of HCl to pure water, we have an increase in the concentration of hydrogen ions. We have more hydrogen ions in the solution than we had before.
Acids are any substance that increases the concentration of hydrogen ions. The concentration of hydrogen ion is really important in biological processes, and we'll learn more about that as we move forward in our course. In our next video, we're going to talk about bases. So, I'll see you all there.