 Okay, so now we're going to, I'm going to show you exactly how to make your PBS and also pH the solution to make sure you have the correct pH. So what I did, I took the liberty of weighing the components ahead of time since you already know how to weigh substances. So I'm just going to add the different components. So first I'm going to add my potassium phosphate monobasic to my, the water. So the water I added here to the beaker is about 200 mils. So you don't want to add the entire 300 mils initially when you're adding your solute to your solvent. That is because on addition of some solutes, you could end up bypassing the required volume that you need. So always stay below the final volume so that it will compensate for the solutes that are added. And also make sure you turn on your stirrer, your magnetic stirrer, and the stirrer bar is in my water. So it's going to mix the solution while I'm adding the components. So now I'm going to add my sodium phosphate dibasic solution powder. And what I'm going to do here, because you may not be able to see it, but some of this the powder is left back. So I'm going to add water to the bowl, the way both to get as much of it out as possible so that I can get an accurate and accurately made solution. So at the same time, the components, the solutes are being mixed into the water. And I'm going to do the same thing with my sodium chloride. So this is my sodium chloride that I'm going to add. And some of the crystals are left back. So now that I don't see any more crystals, I will let the solution continue to mix until I see all the salt dissolving. So the idea here is to make sure that all the solute has dissolved. So I'm looking at the mixture and there's still solutes there. So that means I'll have to let it continue spinning or mixing. So I look at my solution and I don't see any more solutes. So that means that the solutes have completely dissolved. So next, what I need to do is to make sure that I bring my volume up to the correct 300 mil mark. So I'm going to do this. I'm going to do this by, first I have to take out my stir bar. So because this is a magnet, you can use another stir bar to take it out. And I will place it to the side. And then I'm going to use a measuring cylinder to make sure that I bring the volume up to the 300 mil mark. That is what I'm trying to make 300 mils of PBS. So I add my solution. And I look at the volume I have here and it's about 180 mils. So I'm going to add more water. This is water to bring the volume up to 300 mils. So again, what you want to do is to make sure that your eyes are in line with the meniscus. Okay, so it's at 300 mils. That's our final volume. So now I pour this back out and mix a little in the measuring cylinder. And then I'm going to pour it back out into my beaker. And then I'm going to put it back on my stir plate so that the mixture can continue to mix.