Video Transcript

Hello. My name is Walter Unglaub and this is how to determine solubility in chemistry. Solubility is a measure of how much reagent will be consumed in a chemical reaction to saturate the solution. If we consider for example a chemical reaction of silver chloride in solution, say water, we have the silver chloride breaking up into silver ions and chlorine ions. Now we notice that this chemical reaction is balanced, in the sense that for every one atom of silver on the left hand side of the equation we have one one the right hand side. And for every one atom of chlorine on the left hand side we have one on the right hand side to match it. So as this compound is dissolving in the solution of water we're going to be losing some of that solid. OK. And likewise as we're losing this compound in the solution we're increasing at the same rate the amount of silver atoms and the amount of chlorine atoms. So when it comes to determining the solubility we need to first determine what the solubility product is. And that's usually denoted by ksp. And for different types of reactions there's different values of ksps. So for this particular reaction you would have to look it up on a table and it's equal approximately to 1.8 times 10 to the minus 10. So in order to determine the solubility, which is s, we know that the solubility product ksp is defined as the product ag+ and cl- here in terms of s. So that's going to give us s times positive s which is equal to s squared. When we set s squared equal to the tabulated value we can solve for the solubility s. So we have for this example, s is equal to the square root of 1.8 times 10 to the minus 10. And this is approximately equal to 1.34 times 10 to the minus 5 and the units are in moles per liter. And another way of writing this unit is just big M which stands for the molarity. So this is one general process by which one determines the solubility. My name is Walter Unglaub and this is how to determine solubility in chemistry.