Understanding Chemical Bonds and Reactions

Okay, so we just had the three types of chemical bonds. Remember, covalent bonds are the strongest bonds. Hydrogen bonds are the weakest, although ionic bonds are pretty weak, too. Bonds are broken, formed, rearranged during what we call chemical reactions. So chemical reactions are kind of like cooking, where you have certain ingredients, you allow time to form, for it to occur and then you end up with a finished product. So, the order is everything. If you don't follow the instructions, you get really, really bad things in the kitchen. It's not like you can put icing on cookies before you bake them. So chemical pathways are crucial. These are several chemical reactions that occur in a specific sequence. So just like when you download a recipe from Pinterest, it's all about making sure you proceed in correct order. So one of the most common chemical reactions is cellular respiration. If you've ever had biology before, this is the part you hated. Here on this previous slide, oxygen is needed. So that's the difference here. Oxygen is needed. is present, oxygen is not. Well, if you make it to the mitochondria, you get 34 ATP, and carbon dioxide is given off as a waste, which is why you're breathing carbon dioxide on every exhale at this moment. So if I go to Vegas and I put down a dollar and I get $34 back, that's better than two. So either one of these, I'm making energy. Either one of these, I'm coming out ahead, I'm getting ATP. But would you rather have $2 or $34? So the difference is you're supposed to breathe oxygen, as we know. So cellular respiration... is respiration at the cellular level, bringing in oxygen, making carbon dioxide for the sole purpose of making... So in order to perform a chemical reaction, your body needs enzymes. Enzymes are specialized proteins. We're going to see that proteins are the most complicated molecules in your body. Enzymes are biological catalysts. If you're a catalyst, you speed... things up. You get things kind of fired up. Ten trillion times in this case. I can't conceive of a million of anything, let alone a trillion of anything, but I know that if things are sped up ten trillion times, that's freaking fast. So the point is, if you're... relying on breaking down food or some other chemical reaction in your body. And that chemical reaction were to slow down 10 trillion times, you would die. So enzymes are necessary to keep things going. But because they're so complicated, they're really sensitive. I mean, if you think about things that are complicated, they break easily. When I was 16 years old, I got one of the first cell phones. They were these ginormous bag phones that looked like a regular home phone telephone. I mean, size-wise. and then there was a giant magnet you put on top of your car with the antenna it was hilarious and it had a 10-minute cell phone plan ten minutes well now I have the iPhone and I mean of course it comes with like unlimited minutes data of the internet on my phone these old bag phones they didn't have that but if I dropped that bag phone off the top of a building it would have survived whereas I broke the screen of my iPhone dropping it like two feet once so the more complicated something it is the easier it is to break iPhones break way way more than those old kind of rotary dial phones, if you're old enough to remember those. So they're very sensitive, enzymes are. They're sensitive to temperature, they're sensitive to pH, which is acids and bases, and they're sensitive to radiation, which is why living next to nuclear power plants is probably not a good idea. But besides speeding up chemical reactions 10 trillion times, which again is just impossible to think about, they help regulate the speed and the sequence. So making sure that the chemical reactions occur in the proper order. Just like a recipe again, I can't go from step 6 to step 4 to step 3 to step 1 and expect to get a meatloaf. Okay, so different kinds of chemical reactions. There are synthesis reactions. And although the top says combination, I prefer the term synthesize. If you synthesize, you make. So if you look at the picture on the right, you're taking those individual amino acids and making protein. So it looks like individual beads and you're making a necklace. Or if you look on the left there, A plus B equals AB. So all you've done is synthesized. You've built, just like putting these beads into a necklace or putting two Legos together. So we call this anabolic. Anabolic, if you think of anabolic steroids, are there to pump you up. You're just building things. So we're taking little guys, making big guys. This is synthesis. This is also that term we saw in the beginning. beginning a simulation changing its chemical form. One of the most common ways we synthesize molecules in our body is through dehydration. If you're dehydrated, you've lost water. So if you look at this picture, we've taken the short polymer and the monomer, and then if you look in the middle, there's an H and an HO. And then you see the arrow, how they've just pulled water out. If you remember from the chemistry, atoms are made of a single molecule. Hydrogens don't care who they're sharing electrons with as long as they fill their orbitals. So in this example, that short polymer is sharing electrons with the hydrogen. The monomer is sharing his electrons with the hydroxyl, the OH. If we pull the water out, they'll bond together and result in that longer polymer shown below. So dehydration synthesis, water is removed to make little guys bond together to make big molecules. So this is how we build. So we call this synthesis. Decomposition reactions. The good thing is this is a word we use. If something decomposes, it breaks down. So you can see on the far right, we take a starch molecule, so something like some yummy spaghetti or french fries, and we bust it into its pieces of sugar. If you've ever heard of it, it's a good thing. heard of the Atkins diet, you can't have pasta when you're on the Atkins diet, which you think, well pasta's not sweet, but if you look at this example, starch molecules basically break down into sugar. If you look on the left, it says AB yields A plus B. So we've taken a big guy and made two little guys. So this is catabolic. So we had anabolic, pump you up, was to build. Catabolic is to break down. And this is really what digestion is all about. So if you think about it, that's what you're doing all day long. You're building molecules, you're breaking molecules. You're building, breaking, building, breaking, building, breaking, building, breaking. It's exhausting. So how can we break molecules? Also by using water, just a little differently. Through hydrolysis. Hydro means water. Lysis means to break. So hydrolysis is water is added to a large molecule. So if you look at this picture, again, where they're showing that purple arrow, we don't care who we share with. We just want to make sure we're filling those orbitals. So what we're going to do is we're going to going to do is add water to this molecule and he's going to then share with the water. So you can see the bottom picture, we have split that bond and now we have two smaller molecules. So hydrolysis is adding water to make big guys into little guys. And when you break bonds, energy is released. When you build, energy is required. So this is what digestion is all about, is bringing in huge cal proteins and breaking them down into their smaller amino acids. Or bringing in French French fries, huge starch molecules, and making sugar molecules. So you break them into their components by adding water. This is what digestion is all about, and if you think about it, there's lots of water in your digestive system. How many times have you been in an empty room where your stomach has growled all crazy and you can hear the water sloshing around in there? So molecules don't care. Atoms don't care who they're sharing electrons with. They just want to share. So hydrolysis works because we can add water through our digestive system, which is full of water, and entice... these big guys to break into little guys. Chemical reactions, if you've never had chemistry, a chemical formula is shown on the left of the reactants, A plus B. There's always an arrow that tells you the direction, again, kind of like a recipe, and your products, A, B. So the example is carbon dioxide and water bond, they form a weak acid. So it just shows you your ingredients and your products, your results. Reversible reactions. In theory, any chemical reaction is reversible. In theory, if I build something out of Legos, at the end of the day, I can break it down into its Legos. So A plus B yields AB, or I could take AB and split it into A plus B. So chemical bonds that are broken, or made, can easily be broken. An exchange reaction. Basically, this is just showing that trading of atoms again. They don't really care who they're sharing with as long as, again, their orbitals get filled. So if you look, A and B are together. C and D are together in the picture on the right. Then they just switch, and at the end, C and A are together, D and B are together. So it's kind of like going to a party. You have Chad and Diana, and they're dating. You have Amanda and Brent. And then at the end of the party, Chad goes home with Amanda, Diana goes home with Brent. So just two people switching at a party, making a new love connection. Atoms do the same thing. They don't care who they're sharing. They just want to fill those orbitals. Electrolytes. We'll see electrolytes a lot as we move through physiology. Electrolytes are a result of compounds that dissolve in water and release ions. So the one we've already seen before, table salt. So if you look down at the bottom, NaCl comes apart into Na. positive and Cl negative. So remember these are ions when we saw from chemical bonds we got ions whenever we donate or receive an electron. So sodium gets rid of an electron he becomes positive. Chlorine accepts an electron he becomes negative and remember they stick together. But because this is an ionic bond they dissolve very easily in water and what that does is it creates a solution that can conduct electricity. So electron or electrolytes excuse me, are really, really important for us because when these things dissolve in our blood, it means our blood can conduct electricity. And you are an electrical organism. Your muscles and your nerves rely on electricity to fire their messages really, really fast. So if you have an electrolyte imbalance, and that sometimes happens from too much sweating or vomiting or diarrhea, when your electrolytes get out of whack, you'll feel shaky, you'll feel like kind of hallucinogenic. because your muscles and your nerves just can't fire properly. So the term for positive ions are cations, the term for negative ions are anions. I always remember this, it's pretty stupid, but I always remember this because cations, I think cats make me happy, make me positive. And anion, when you first look at the word, it kind of looks like onion, and onions make me sad, because when you cut them it makes you cry. So that's a really stupid way to remember those terms, and I'll give you lots and lots of dumb ways to remember things. So when we're looking at electrolytes, we want to measure their strength. So we have something that's called the pH scale, which gives us a measurement of acids, bases, and buffers. An acid is an electrolyte. So we just saw in the previous slide that that means it's something that dissolves in water. And in this case, it releases hydrogen ions. So that's not a very interesting definition for an acid. To me, an acid is something that like melts your skin. But truly, an acid is just... something that comes apart in water and releases hydrogen ions. So if you see hydrogen ions, you know you're talking about an acid. So some examples, we have hydrochloric acid, which is one of the strongest acids we see in lab. When hydrochloric acid separates in water, you get H pluses and Cl minus. So you get positive cations of hydrogen, negative anions of chlorine. That's what tells us it's an acid. A base is an electrolyte, which remember means comes apart in water. In this case, releases hydroxyl, OH negative ions. So an example of a really strong base we see in lab, sodium hydroxide. When sodium hydroxide comes apart in water, you get Na plus and OH negative. So you get a positive sodium cation and a negative hydroxide anion. So pH is a measurement of the concentration of sodium hydroxide. concentration of hydrogen ions in solution. A pH of less than 7 is acidic, a pH of greater than 7 is basic, and 7 right down the middle is neutral. So if we look at this, a pH again is the measurement of this number of molecules. In chemistry we call this molarity. We don't really care because this isn't a chemistry class. What we do care is the pH scale is based on how many hydrogen ions are present. Another thing we care about is that it is a log scale. So the change of one number on the pH scale represents actually a ten-fold change. So if you're comparing a solution with a pH of 4 to a solution with a pH of 5, there's a 10 times difference. If I'm comparing a solution with a pH of 2 to a solution with a pH of 4, there's a 100 times difference. So every notch you go up on this little color wheel shown below is actually 10 times stronger or 10 times weaker. So it's based on... on what's called a mathematical log scale, which is based on the power of 10. Now if you look at the pH scale, what I want you to know about it is that it goes from 0 to 14 and that 7 is neutral. I don't need you to know what the pH of beer is, although I can certainly remember fun facts like that. The examples on this are just to give us perspective so we can kind of know what these pHs mean. This scale is kind of weird. Most of the time when you rank things, like say you have a scale of 1 to 10, we know a 1 is equal to 1 isn't very good, and a 10 is really good. But this scale isn't like that. The pH scale is kind of strange. If you look at the very bottom, there are arrows pointing to both ends, and 7 being neutral in the middle. So if you look on the left, it says increasing... acidic heading towards the zero. If you look on the right it says increasingly basic heading towards 14. That's what I need you to know. I need you to know what these numbers mean, not actual representatives of how what's the pH of household bleach. So for example, I want you to know a pH of 1 is much stronger than a pH of 2 and that it's an acid. Or I would want you to know that a 12 is much stronger than a 10 and on that end are the bases and then again 7 is a pH of 1. is perfectly neutral. So the acids are 1 through 6 and that means there's more hydrogens. The bases are 8 through 14 and that means there's more hydroxyls. But keep in mind every notch is a 10 difference. So if we look at the actual examples, wine and vinegar ranges around a 2.4 to 3.5, so let's say around a 3. Stomach acid is around a 0. Or lemon juice around a 2 and wine around a 3. So if we compare like wine to lemon juice, wine is 10 times weaker acidic than lemon juice. Or we could say lemon juice is 10 times stronger than wine. Stomach acid, a pH of around 1. It ranges really from 1 to 3, but let's just say 1. Gastric juice is what it's listed there. If your stomach is a pH of 1, it is 100 times stronger than beer. a pH of 3, or wine. Or lemon juice is 10 times weaker than stomach acid. So depending on which direction you go, you're either getting stronger or weaker. As you head towards 1 and 14, you're getting extremely strong. 1 would be a really strong acid. 12, 13, 14 would be really strong bases. Whereas when you hit around a 6, that's a very, very weak acid, to the point where it's hardly acidic at all. Milk. Milk is around a pH of 6. Urine is around a pH of 6. And if it burns when you pee, that's probably chlamydia. One in four college students has chlamydia. You should probably go and get that checked. So normal urine doesn't burn, of course. Household bleach, however, being a pH of about 9.5. If you've ever cleaned with bleach and you had an open cut on your finger, it burns like hell. Same thing with oven cleaner. Oven cleaner is up there around a 13.4. If you've ever seen oven cleaner, it has all these crazy warnings on its label because it's so dangerous. Whereas, neutrality is pure water. Being a pH of 7 is rare. Because if you think about it, most things have an opinion one way or another. There's not a lot of, like, neutral things. There's not a lot of people that if you say, I'm going to cut your face off, that they say, okay, go ahead and cut my face off. Because most people would have an opinion one way or another about that. Well, in chemistry, it's the same thing. There's not a lot of pure, neutral 7 on the pH scale things. Really, the only only example is water. And I'm not talking about Danville water. I'm talking about NASA purified water that's sealed in a vacuum where nothing can touch it. Because if you think about it, even if we could purify water, as soon as it runs through a pipe, it's going to dissolve stuff. So pure water is neutral because water is made of H's and OH's. So they cancel each other out. So just some examples for homeostasis. Remember, homeostasis is maintaining our constant internal environment. Some examples of parts of our body that have to be in certain ranges and you do not have to know these numbers. But blood, blood needs to be between 7.35 and 7.45. Stomach, anywhere from 0.9 to 3. Your stomach needs to be very acidic because it has to break down molecules. The small intestine, 7.4 to 7.8 because it's mixed with pancreatic juices and other intestinal juices. Urine, anywhere from 5 to 8 is considered normal. So the point of showing you this is to go back to homeostasis again, maintaining a constant internal environment, and to show us that different parts of the body have different pHs depending on their function. The blood is almost neutral, whereas the stomach, we need it to be acidic. For the blood to do its job, it needs to be around neutral. For the stomach to do its job, whereas chewing up molecules, it has to be pretty acidic. So acidosis versus alkalosis. Acid is heading towards the acids. Alkaline means that the blood is not neutral. So we're heading towards the bases. So blood needing to be between 7.35 and 7.45 is a crucial part of your homeostasis. That's pretty picky. That's a pretty narrow range. So you work pretty hard every second of every day to keep yourself within this range. If your pH gets lower than 7.35, we call this acidosis because you're heading towards the acids. Being diabetic, starvation, having lots of protein in your diet or severe diarrhea can cause this. When you eat a lot of protein, you make a lot of natural. acids during the process of breaking it down. If the pH is higher than 7.45, we call it alkalosis. Vomiting or alkaline drugs, basic drugs, can cause this. It's actually quite a bit less common than the other. So if you've ever heard of ketoacidosis, referring to diabetes, pretty sadly a pretty common thing. But your body works really, really hard to keep you within this range. Right now, we just need to know a buffer helps us resist pH changes. Because of homeostasis, it's very... very important to maintain pH, temperature, breathing rate, heart rate, and all those other things that we've

So, the order is everything. If you don't follow the instructions, you get really, really bad things in the kitchen. It's not like you can put icing on cookies before you bake them. So chemical pathways are crucial. These are several chemical reactions that occur in a specific sequence.

So just like when you download a recipe from Pinterest, it's all about making sure you proceed in correct order. So one of the most common chemical reactions is cellular respiration. If you've ever had biology before, this is the part you hated. Here on this previous slide, oxygen is needed.

So that's the difference here. Oxygen is needed. is present, oxygen is not.

Well, if you make it to the mitochondria, you get 34 ATP, and carbon dioxide is given off as a waste, which is why you're breathing carbon dioxide on every exhale at this moment. So if I go to Vegas and I put down a dollar and I get $34 back, that's better than two. So either one of these, I'm making energy.

Either one of these, I'm coming out ahead, I'm getting ATP. But would you rather have $2 or $34? So the difference is you're supposed to breathe oxygen, as we know. So cellular respiration...

is respiration at the cellular level, bringing in oxygen, making carbon dioxide for the sole purpose of making... So in order to perform a chemical reaction, your body needs enzymes. Enzymes are specialized proteins. We're going to see that proteins are the most complicated molecules in your body. Enzymes are biological catalysts.

If you're a catalyst, you speed... things up. You get things kind of fired up. Ten trillion times in this case.

I can't conceive of a million of anything, let alone a trillion of anything, but I know that if things are sped up ten trillion times, that's freaking fast. So the point is, if you're... relying on breaking down food or some other chemical reaction in your body. And that chemical reaction were to slow down 10 trillion times, you would die. So enzymes are necessary to keep things going.

But because they're so complicated, they're really sensitive. I mean, if you think about things that are complicated, they break easily. When I was 16 years old, I got one of the first cell phones.

They were these ginormous bag phones that looked like a regular home phone telephone. I mean, size-wise. and then there was a giant magnet you put on top of your car with the antenna it was hilarious and it had a 10-minute cell phone plan ten minutes well now I have the iPhone and I mean of course it comes with like unlimited minutes data of the internet on my phone these old bag phones they didn't have that but if I dropped that bag phone off the top of a building it would have survived whereas I broke the screen of my iPhone dropping it like two feet once so the more complicated something it is the easier it is to break iPhones break way way more than those old kind of rotary dial phones, if you're old enough to remember those.

So they're very sensitive, enzymes are. They're sensitive to temperature, they're sensitive to pH, which is acids and bases, and they're sensitive to radiation, which is why living next to nuclear power plants is probably not a good idea. But besides speeding up chemical reactions 10 trillion times, which again is just impossible to think about, they help regulate the speed and the sequence.

So making sure that the chemical reactions occur in the proper order. Just like a recipe again, I can't go from step 6 to step 4 to step 3 to step 1 and expect to get a meatloaf. Okay, so different kinds of chemical reactions.

There are synthesis reactions. And although the top says combination, I prefer the term synthesize. If you synthesize, you make. So if you look at the picture on the right, you're taking those individual amino acids and making protein.

So it looks like individual beads and you're making a necklace. Or if you look on the left there, A plus B equals AB. So all you've done is synthesized. You've built, just like putting these beads into a necklace or putting two Legos together. So we call this anabolic.

Anabolic, if you think of anabolic steroids, are there to pump you up. You're just building things. So we're taking little guys, making big guys. This is synthesis.

This is also that term we saw in the beginning. beginning a simulation changing its chemical form. One of the most common ways we synthesize molecules in our body is through dehydration.

If you're dehydrated, you've lost water. So if you look at this picture, we've taken the short polymer and the monomer, and then if you look in the middle, there's an H and an HO. And then you see the arrow, how they've just pulled water out.

If you remember from the chemistry, atoms are made of a single molecule. Hydrogens don't care who they're sharing electrons with as long as they fill their orbitals. So in this example, that short polymer is sharing electrons with the hydrogen.

The monomer is sharing his electrons with the hydroxyl, the OH. If we pull the water out, they'll bond together and result in that longer polymer shown below. So dehydration synthesis, water is removed to make little guys bond together to make big molecules.

So this is how we build. So we call this synthesis. Decomposition reactions. The good thing is this is a word we use. If something decomposes, it breaks down.

So you can see on the far right, we take a starch molecule, so something like some yummy spaghetti or french fries, and we bust it into its pieces of sugar. If you've ever heard of it, it's a good thing. heard of the Atkins diet, you can't have pasta when you're on the Atkins diet, which you think, well pasta's not sweet, but if you look at this example, starch molecules basically break down into sugar. If you look on the left, it says AB yields A plus B. So we've taken a big guy and made two little guys.

So this is catabolic. So we had anabolic, pump you up, was to build. Catabolic is to break down. And this is really what digestion is all about. So if you think about it, that's what you're doing all day long.

You're building molecules, you're breaking molecules. You're building, breaking, building, breaking, building, breaking, building, breaking. It's exhausting.

So how can we break molecules? Also by using water, just a little differently. Through hydrolysis.

Hydro means water. Lysis means to break. So hydrolysis is water is added to a large molecule.

So if you look at this picture, again, where they're showing that purple arrow, we don't care who we share with. We just want to make sure we're filling those orbitals. So what we're going to do is we're going to going to do is add water to this molecule and he's going to then share with the water.

So you can see the bottom picture, we have split that bond and now we have two smaller molecules. So hydrolysis is adding water to make big guys into little guys. And when you break bonds, energy is released.

When you build, energy is required. So this is what digestion is all about, is bringing in huge cal proteins and breaking them down into their smaller amino acids. Or bringing in French French fries, huge starch molecules, and making sugar molecules.

So you break them into their components by adding water. This is what digestion is all about, and if you think about it, there's lots of water in your digestive system. How many times have you been in an empty room where your stomach has growled all crazy and you can hear the water sloshing around in there?

So molecules don't care. Atoms don't care who they're sharing electrons with. They just want to share. So hydrolysis works because we can add water through our digestive system, which is full of water, and entice... these big guys to break into little guys.

Chemical reactions, if you've never had chemistry, a chemical formula is shown on the left of the reactants, A plus B. There's always an arrow that tells you the direction, again, kind of like a recipe, and your products, A, B. So the example is carbon dioxide and water bond, they form a weak acid. So it just shows you your ingredients and your products, your results.

Reversible reactions. In theory, any chemical reaction is reversible. In theory, if I build something out of Legos, at the end of the day, I can break it down into its Legos. So A plus B yields AB, or I could take AB and split it into A plus B. So chemical bonds that are broken, or made, can easily be broken.

An exchange reaction. Basically, this is just showing that trading of atoms again. They don't really care who they're sharing with as long as, again, their orbitals get filled.

So if you look, A and B are together. C and D are together in the picture on the right. Then they just switch, and at the end, C and A are together, D and B are together. So it's kind of like going to a party. You have Chad and Diana, and they're dating.

You have Amanda and Brent. And then at the end of the party, Chad goes home with Amanda, Diana goes home with Brent. So just two people switching at a party, making a new love connection.

Atoms do the same thing. They don't care who they're sharing. They just want to fill those orbitals. Electrolytes. We'll see electrolytes a lot as we move through physiology.

Electrolytes are a result of compounds that dissolve in water and release ions. So the one we've already seen before, table salt. So if you look down at the bottom, NaCl comes apart into Na. positive and Cl negative.

So remember these are ions when we saw from chemical bonds we got ions whenever we donate or receive an electron. So sodium gets rid of an electron he becomes positive. Chlorine accepts an electron he becomes negative and remember they stick together. But because this is an ionic bond they dissolve very easily in water and what that does is it creates a solution that can conduct electricity. So electron or electrolytes excuse me, are really, really important for us because when these things dissolve in our blood, it means our blood can conduct electricity.

And you are an electrical organism. Your muscles and your nerves rely on electricity to fire their messages really, really fast. So if you have an electrolyte imbalance, and that sometimes happens from too much sweating or vomiting or diarrhea, when your electrolytes get out of whack, you'll feel shaky, you'll feel like kind of hallucinogenic. because your muscles and your nerves just can't fire properly.

So the term for positive ions are cations, the term for negative ions are anions. I always remember this, it's pretty stupid, but I always remember this because cations, I think cats make me happy, make me positive. And anion, when you first look at the word, it kind of looks like onion, and onions make me sad, because when you cut them it makes you cry.

So that's a really stupid way to remember those terms, and I'll give you lots and lots of dumb ways to remember things. So when we're looking at electrolytes, we want to measure their strength. So we have something that's called the pH scale, which gives us a measurement of acids, bases, and buffers.

An acid is an electrolyte. So we just saw in the previous slide that that means it's something that dissolves in water. And in this case, it releases hydrogen ions. So that's not a very interesting definition for an acid. To me, an acid is something that like melts your skin.

But truly, an acid is just... something that comes apart in water and releases hydrogen ions. So if you see hydrogen ions, you know you're talking about an acid. So some examples, we have hydrochloric acid, which is one of the strongest acids we see in lab. When hydrochloric acid separates in water, you get H pluses and Cl minus.

So you get positive cations of hydrogen, negative anions of chlorine. That's what tells us it's an acid. A base is an electrolyte, which remember means comes apart in water. In this case, releases hydroxyl, OH negative ions.

So an example of a really strong base we see in lab, sodium hydroxide. When sodium hydroxide comes apart in water, you get Na plus and OH negative. So you get a positive sodium cation and a negative hydroxide anion. So pH is a measurement of the concentration of sodium hydroxide. concentration of hydrogen ions in solution.

A pH of less than 7 is acidic, a pH of greater than 7 is basic, and 7 right down the middle is neutral. So if we look at this, a pH again is the measurement of this number of molecules. In chemistry we call this molarity.

We don't really care because this isn't a chemistry class. What we do care is the pH scale is based on how many hydrogen ions are present. Another thing we care about is that it is a log scale. So the change of one number on the pH scale represents actually a ten-fold change. So if you're comparing a solution with a pH of 4 to a solution with a pH of 5, there's a 10 times difference.

If I'm comparing a solution with a pH of 2 to a solution with a pH of 4, there's a 100 times difference. So every notch you go up on this little color wheel shown below is actually 10 times stronger or 10 times weaker. So it's based on... on what's called a mathematical log scale, which is based on the power of 10. Now if you look at the pH scale, what I want you to know about it is that it goes from 0 to 14 and that 7 is neutral. I don't need you to know what the pH of beer is, although I can certainly remember fun facts like that.

The examples on this are just to give us perspective so we can kind of know what these pHs mean. This scale is kind of weird. Most of the time when you rank things, like say you have a scale of 1 to 10, we know a 1 is equal to 1 isn't very good, and a 10 is really good. But this scale isn't like that. The pH scale is kind of strange.

If you look at the very bottom, there are arrows pointing to both ends, and 7 being neutral in the middle. So if you look on the left, it says increasing... acidic heading towards the zero.

If you look on the right it says increasingly basic heading towards 14. That's what I need you to know. I need you to know what these numbers mean, not actual representatives of how what's the pH of household bleach. So for example, I want you to know a pH of 1 is much stronger than a pH of 2 and that it's an acid.

Or I would want you to know that a 12 is much stronger than a 10 and on that end are the bases and then again 7 is a pH of 1. is perfectly neutral. So the acids are 1 through 6 and that means there's more hydrogens. The bases are 8 through 14 and that means there's more hydroxyls. But keep in mind every notch is a 10 difference.

So if we look at the actual examples, wine and vinegar ranges around a 2.4 to 3.5, so let's say around a 3. Stomach acid is around a 0. Or lemon juice around a 2 and wine around a 3. So if we compare like wine to lemon juice, wine is 10 times weaker acidic than lemon juice. Or we could say lemon juice is 10 times stronger than wine. Stomach acid, a pH of around 1. It ranges really from 1 to 3, but let's just say 1. Gastric juice is what it's listed there.

If your stomach is a pH of 1, it is 100 times stronger than beer. a pH of 3, or wine. Or lemon juice is 10 times weaker than stomach acid.

So depending on which direction you go, you're either getting stronger or weaker. As you head towards 1 and 14, you're getting extremely strong. 1 would be a really strong acid.

12, 13, 14 would be really strong bases. Whereas when you hit around a 6, that's a very, very weak acid, to the point where it's hardly acidic at all. Milk.

Milk is around a pH of 6. Urine is around a pH of 6. And if it burns when you pee, that's probably chlamydia. One in four college students has chlamydia. You should probably go and get that checked. So normal urine doesn't burn, of course.

Household bleach, however, being a pH of about 9.5. If you've ever cleaned with bleach and you had an open cut on your finger, it burns like hell. Same thing with oven cleaner.

Oven cleaner is up there around a 13.4. If you've ever seen oven cleaner, it has all these crazy warnings on its label because it's so dangerous. Whereas, neutrality is pure water. Being a pH of 7 is rare.

Because if you think about it, most things have an opinion one way or another. There's not a lot of, like, neutral things. There's not a lot of people that if you say, I'm going to cut your face off, that they say, okay, go ahead and cut my face off. Because most people would have an opinion one way or another about that. Well, in chemistry, it's the same thing.

There's not a lot of pure, neutral 7 on the pH scale things. Really, the only only example is water. And I'm not talking about Danville water.

I'm talking about NASA purified water that's sealed in a vacuum where nothing can touch it. Because if you think about it, even if we could purify water, as soon as it runs through a pipe, it's going to dissolve stuff. So pure water is neutral because water is made of H's and OH's. So they cancel each other out. So just some examples for homeostasis.

Remember, homeostasis is maintaining our constant internal environment. Some examples of parts of our body that have to be in certain ranges and you do not have to know these numbers. But blood, blood needs to be between 7.35 and 7.45. Stomach, anywhere from 0.9 to 3. Your stomach needs to be very acidic because it has to break down molecules. The small intestine, 7.4 to 7.8 because it's mixed with pancreatic juices and other intestinal juices.

Urine, anywhere from 5 to 8 is considered normal. So the point of showing you this is to go back to homeostasis again, maintaining a constant internal environment, and to show us that different parts of the body have different pHs depending on their function. The blood is almost neutral, whereas the stomach, we need it to be acidic.

For the blood to do its job, it needs to be around neutral. For the stomach to do its job, whereas chewing up molecules, it has to be pretty acidic. So acidosis versus alkalosis.

Acid is heading towards the acids. Alkaline means that the blood is not neutral. So we're heading towards the bases.

So blood needing to be between 7.35 and 7.45 is a crucial part of your homeostasis. That's pretty picky. That's a pretty narrow range. So you work pretty hard every second of every day to keep yourself within this range. If your pH gets lower than 7.35, we call this acidosis because you're heading towards the acids.

Being diabetic, starvation, having lots of protein in your diet or severe diarrhea can cause this. When you eat a lot of protein, you make a lot of natural. acids during the process of breaking it down.

If the pH is higher than 7.45, we call it alkalosis. Vomiting or alkaline drugs, basic drugs, can cause this. It's actually quite a bit less common than the other.

So if you've ever heard of ketoacidosis, referring to diabetes, pretty sadly a pretty common thing. But your body works really, really hard to keep you within this range. Right now, we just need to know a buffer helps us resist pH changes.

Because of homeostasis, it's very... very important to maintain pH, temperature, breathing rate, heart rate, and all those other things that we've

Transcript for:Understanding Chemical Bonds and Reactions

Transcript for:
Understanding Chemical Bonds and Reactions