 Okay, so this is going to be the second part of our two-part videos on solutions and dilutions. And so in part one, we kind of talked about solutions and concentrations and dilutions and their definitions and their importance and spent the majority of that video talking about dilutions. And so this one we're going to be concentrating on solutions and kind of the nomenclature or the terminology related to solutions and how we make up solutions. So as we said last time, the kind of notion that kind of ties solutions and dilutions and all these things together are concentration. And for this discussion, we're going to kind of use a mathematical formula and we're going to say the amount of solute over the volume of solution, right? And we're talking about again volume of solution, not the volume of the solvent. I remember the volume of the solution is going to be the solute plus the solvent. And so this solution is going to be kind of the total volume of the solution. So let's look at some of the different terminologies to say with a different kind of solution. And we said percent solution, right? And this kind of information I'm actually working off to kind of preamble to the lab that you're doing on solution. So the first thing is percent and when we think percent, we're thinking per hundred. So if we had 10 would be 10% of a hundred or if we had say 30 people in the classroom and 15 people went on a field trip, we could say that 50% or 15 out of 30, 50% went on the field trip, 50% stayed home. But it's based on 100, we'll see how we do that. And we're going to talk about a couple ways of one with volume to volume. And we say that that's V to V. And so these would be solutions where your solute would be in liquid form typically. So you'd be adding amount of liquid to an amount of liquid. And so in the case gave in the lab would be 5% volume to volume. So if we say put 100 in the denominator, so we think 100 mils, right? And so 5% is 5100, so we would have 5 mils of solute to 100 mils of arrogant solution. Remember not solvent, because in the case of the volume, the 100 mils is a total. So we would have 5 mils of the solute and 95 mils. So if we wanted to make 5% acidic acid, we would have 5 mils of acidic acid and bring it to volume. Remember that bring to volume to 100 mils. So it's 5 out of 100. Now if you were wanting to make a liter, right, you would have to have 50 mils of the 500. Remember it's going to be a proportion. So if you take it to 100, if you base it on 100 and then do your proportion for whatever volume solution you're wanting to make, then that will work for you. Now the other would be weight to volume, right, or WV, right? And that would tend to be when your solute would be a solid and then again your solution would be water, ethanol, what your solvent is. So the example I gave was 7% weight to volume, right? So in this case now the percentage, we're going to say 7 grams of solute for 100 mils of solution. And so our rationale for this is if you recall, we take the mass of water per gram per mil. So this 100 mils is 100 grams, but we're still calling it 100 mils. So it's 7 grams per 100, 7%. And then again if you want to make a liter, you'll be proportionally 10 fold more, so you'd have to have 70 grams per liter. So think of the percent that's based on this 100 mils of total volume of solution. Okay, so B, our second way of talking about concentration of solutions would be molar solutions. And of course we're talking about concentration in terms of molarity. So we remember we had this molarity is moles per liter. So in this case if we had a 3.5 molar solution, we would say it would be 3.5 moles per liter, one liter of solution. So in this case if we were making a 3.5 molar solution, we would dissolve 3.5 moles of solute and bring to volume at one liter. So that's our molar solution. And the third is what I just call direct notation. It's when you basically just have an amount or some volume. So in a situation like this it may say that you want a concentration, let me, I can write a little bit in that concentration, 20 milligrams per mil. So if you were making one mil you would just weigh out 20 milligrams and dissolve it, bring it to the volume of a mil. Now typically that's your concentration, right, and it kind of lets you decide what kind of volume do you want, right? So if I wanted to make 100 mils of solution at a concentration of 20 milligrams per mil, I'd have to say 20 milligrams per mil times 100 mils. So I would need 2,000 milligrams, right, or that's equivalent of gram, right, 2,000 milligrams per mil of 100 mils. So if you have 2,000 by 100 and that's 20 milligrams per mil. So it gives you your recipe basically in terms of concentration, like the one previous said, if you wanted 3.5 molar solution to definition 3.5 moles per liter, if you're making more or less of that then you have to adjust for that. So your recipe is given in the concentration 3.5 moles per liter, right, percentages, right, taken to 100, and then what I just called the kind of direct notation is it'll tell you what weight you have per volume. So our lab handout has a couple of examples.