here. We're going to say that extremely dilute solution concentrations are expressed in parts per million, abbreviated as ppm or parts per billion, or bring it as ppb. Now we're going to say here units can either be in mass or volume when it comes to ppm or ppb. Now, let's take a look at parts per million. We're gonna say this represents the number of parts either in grams or milliliters per one million parts. And remember, one million is 10 to the sixth in a quick solution. Helpful thing to help to help you with parts per million is that one parts per million is equivalent to one mg per one leader. So here we take a look at parts per million. We can look at it, look at it and neither are form of mass or in a form of volume. If we're looking at parts per million in terms of mass, we're gonna say it equals grams of solute divided by grams of solution times 10 to the six. And if we're looking at parts per million in terms of volume, then it becomes milliliters of solute divided by milliliters of solution times 10 to the six. So this setup should be kind of reminiscent of mass percent where it be grams over grams times 100%. Now, instead of doing 100% we're now dealing with 10 to the six because we're dealing with a million parts, one million parts. All right, so just keep in mind, we deal with PPM and later on ppb when discussing very extremely diluted concentrations.