 We talked about water. We talked about solutions. How is pH related to this? Well, pH is a measure of Hydrogen ion concentration in a solution now a Couple things first of all, I don't know if I've told you this yet, but when you put something in brackets That can mean Concentration of so I often will abbreviate by saying, okay, let's talk about the concentration of sodium Ions in your blood. Let's talk about the concentration of calcium ions in your blood And I just shorthand it with those little brackets pH Deals with hydrogen ions hydrogen ions are like the simplest thing Possible remember hydrogen was element number one it consists of one electron and one proton and If you make it into a positively charged ion, you just take away its electron So all that's left is a proton It's so important to To Manage the hydrogen ion concentration Because it impacts the structure of pretty much all other biomolecules in your body So we're gonna talk about pH and and get a sense of What it actually is Okay, so hydrogen ions like where would these things even come from well, it's super interesting because water H2o yes actually dissociates Into hydrogen ions and What would be left if we took a water molecule and we took one of the hydrogen atoms off and left an electron behind what's gonna be left over an OH that has a negative charge this is called a hydroxide Ion and The hydrogen the positively charged hydrogen is called a high hydrogen It's a hydrogen ion Sometimes and this is why I this is why I couldn't talk sometimes You get to hydrogen. I mean these are water molecules And this also goes back and forth sometimes The hydrogen ion doesn't it rips off of one of the water molecules, but it doesn't Go rogue and just float around by itself. It actually combines with another water molecule So that you get H3o Which has a positive charge and then you have you have that left over Hydroxide ion with a negative charge. So I tend to Prefer this version the top version just because it feels easier to me to visualize one water molecule Breaking off, but if you do hear people talking about this They refer to this right here as a hydronium a hydronium ion and it is Functionally the same as a hydrogen ion. It's it's it's what we're measuring when we measure pH now. We're gonna talk I I said pH is a measure of hydrogen ion concentration And so we're gonna look at how that like what the what the Scale looks like and how It actually is a measure of those hydrogen ions Before we do that. I want to name This I want to address These little arrows that are going back and forth We know in a chemical reaction the arrow indicates the direction that the reaction is proceeding right, so we have reactants that React to form Products and the arrow points to the direction so you know if you throw What was it glucose and oxygen into a mitochondrion and have it go through cellular respiration? we're gonna get carbon dioxide and water and energy out of that reaction like we're gonna move it in one direction if Your arrow points in both directions. You have a thing called dynamic equilibrium. Where'd it go? that was That was a lot of pages that went flying by us This is an example of dynamic equilibrium and It's a little I don't know. I think I don't know why but dynamic equilibrium always feels Tricky to me. I don't know why but all it's saying is that The rate that a reaction happens in one direction is Equal to the rate that it happens in the other direction So there is no net change in the environment It's dynamic because there there are reactions happening. We are Going from right to left, but every time we go from right to left We also go from left to right and so ultimately there is no net change. We're in an Equilibrium state common for critters especially to Put energy into a system to maintain a dynamic equilibrium it also means that We can use this to manage the pH of a system Okay, so let's talk about pH if pH is a measure of the hydrogen ions in a solution the concentration of hydrogen ions in a solution Then we're gonna have I Don't know. Let's do this. We'll say we have acidic solutions that have Well, I don't know how to roll this all out for you. We have basic Solutions and we have neutral Solutions and these all Are on a spectrum the spectrum goes from zero to 14 and Neutral is seven now I'm gonna blow your mind into little pieces really fast and then I'm gonna do an Activity with you to help build the pH scale Because this is not Intuitive, but this is the only thing I'm gonna tell you and then we're gonna move into activity land I'm gonna tell you that acidic substances have high hydrogen ion concentration and Basic substances What do you think? Have low hydrogen ion concentration does anybody want to Mutiny Object, so do we have any objections to this because the fact is that that is Backwards, right? Wait a minute. Why do I have to remember that a high hydrogen ion concentration is actually a low number? And that's acidic It doesn't make sense until We do a thing that I'm gonna do with you in just a second. I'm gonna explain it to you so come along and Come along with your brain ready to participate this next clip is going to be an interactive Clip I expect to hear you yelling back at me loud and proud home kids loud and proud