Acids and Bases - Video Tutorials & Practice Problems
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Acids and Bases
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In this video we're going to begin our lesson on acids and bases. And so what you all need to know is that many biological concentration of dissolved hydrogen ions, or H+ ions, in the aqueous solution. And so the concentration of dissolved hydrogen ions can really just be abbreviated by brackets with an H plus in the middle. And so anytime you see brackets in science, it means the concentration of. And so what this brackets means is the concentration of hydrogen ions. And so acids and bases are substances that directly affect the concentration of hydrogen ions. And once again, the concentration of hydrogen ions is really, really important because that will strongly affect many biological processes that we'll talk about later in our course. But in our next lesson video, we're going to talk more details about exactly how acids directly affect the hydrogen ion concentration. And then later in a different video, we'll talk about how bases directly affect the hydrogen ion concentration. And so I'll see you all in our next lesson video to talk about acids.
2
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Acids
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In this video, we're going to introduce acids. And so acids are really just any chemical that increases a solution's concentration of hydrogen ions or H+ ions. And once again, recall that the concentration of hydrogen ions can be abbreviated with just brackets like this and it h+ in the middle. Because anytime we see the brackets in science, we know it means the concentration of of what's in between the brackets. So this is the concentration of hydrogen ions here. So acids will increase the concentration of hydrogen ions in solution. And so if we take a look at our example down below at the addition of hydrochloric acid or HCl to water, we could see an example of an acid. So notice over here on the far left, we're showing you 4 different molecules of hydrochloric acid or HCl, 1, 2, 3, and 4. And as its name implies, hydrochloric acid is an acid, which means that when we add it to water, it is going to increase the concentration of hydrogen ions. And so what happens when we add a hydrochloric acid molecule to water, it will actually split up into 2 components. It will split up into a hydrogen ion, and it will split split up into a chloride anion. And so the h plus, and the Cl minus, is what each HCl molecule will split up into when we add it into pure water. And so notice over here in this beaker, we have these chloride anions here, 3 of 4 of them for that matter since we have 4 HCl molecules, and we also have 4 hydrogen ions. And so ultimately, what we can see is that through the addition of HCl2 pure water, at the end, we have an increase in the concentration of hydrogen ions. We have more hydrogen ions in the solution than what we had before. And so, we can say that we have increased hydrogen ion concentration. And really that is it for acids. Acids are any substance that will increase the concentration of hydrogen ion. And once again, the concentration of hydrogen ion is really, really important when it comes to biological processes, and we'll get to learn more about that as we move forward in our course. But in our next video, we're gonna talk about bases. So I'll see you all there.
3
concept
Bases
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Video transcript
So now that we've introduced acids in our previous lesson videos, in this video we're going to introduce bases. And so bases are practically the opposite of acids and that is because instead of increasing a solution's hydrogen ion concentration, bases are any chemical that decreases a solution's hydrogen ion concentration or concentration of hydrogen ions. And so an example of a base is actually sodium hydroxide whose chemical formula is NaOH. And so if we take a look at our example image down below we'll be able to see an example of a base specifically the addition of Sodium Hydroxide or NaOH to water. And so notice on the left hand side over here what we're showing you are 3 different Sodium Hydroxide molecules, 1, 2, and 3. And so when each of these sodium hydroxide, molecules is added to water, the sodium hydroxide is going to dissociate or break apart or ionize into these ions. And so for example, this Sodium Hydroxide molecule will break apart into a Sodium ion or Na+ and a hydroxide ion or Oh minus. And so again this is going to be true for each of these sodium hydroxide ions. And so notice upon the addition of the Sodium Hydroxide to the pure water, the ions are going to break apart. So you'll see 3 hydroxide ions and 3 sodium ions. Now you'll notice that even in pure water over here we're showing you some hydrogen ions and this is going to be true even for pure water there will be some hydrogen ions. And this is because water has the ability to auto ionize which is something that we'll get to talk more about later in our course. But for now notice that there are some hydrogen ions even in pure water and so you can see those hydrogen ions over here as well. And so what's important to note is that each of these hydroxide ions is going to interact with a hydrogen ion, And so you will see these interactions right here and when the hydroxide interact with the hydrogen ion they create water molecules as you see right here. And so what you'll notice is that the concentration of hydrogen ions is being decreased because of the addition of this sodium hydroxide. And so whereas there were 3 hydrogen ions in the pure water and this beaker here, and the final beaker notice that there are not any hydrogen ions being shown, and so what this is showing is, the decreased hydrogen ion concentration. And so once again, when a chemical decreases a solution's concentration of hydrogen ions that chemical is referred to as a base. So sodium hydroxide is indeed a base. And so, once again the concentration of hydrogen ions is incredibly relevant to living systems, and so any substance that can change a concentration of hydrogen ion is going to be relevant as well and so bases are very important. And so this here concludes our brief introduction to basis and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.
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Problem
Problem
Which of the following reactions is most consistent with that of a base?
a) NH4+ → NH3 + H+
b) H2CO3 → HCO3- + H+
c) NaOH → Na+ + OH-
d) HCl → H+ + Cl-
A
a) NH4+ → NH3 + H+
B
b) H2CO3 → HCO3- + H+
C
c) NaOH → Na+ + OH-
D
d) HCl → H+ + Cl-
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Problem
Problem
The addition of an acid like HCl to an aqueous solution (pure water) would result in:
a) An increase in pH only.
b) Both the release of H+ and an increase in pH.
c) Both the release of H+ and a decrease in pH.
d) The release of H+ into the solution only.
e) A decrease in pH only.
A
An increase in pH only.
B
Both the release of H+ and an increase in pH.
C
Both the release of H+ and a decrease in pH.
D
The release of H+ into the solution only.
E
A decrease in pH only.
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Problem
Problem
In what way(s) do bases work to increase the pH of a solution?
a) Increasing the concentration of hydroxide ions.
b) Decreasing the concentration of hydrogen ions.
c) Decreasing the concentration of hydroxide ions.