So in the past we learned that our activity coefficient which is represented by gamma and ionic strength which is represented by mu of a solution could be closely and accurately related by using the extended double Debbie huckle equation here, we'd say that the log of the activity coefficient equals negative 0.51 times the charge of the ion squared times the square root of your ionic strength divided by one plus alpha here represents the size parameter of the ion, usually in units of nanometers times the square root of your ionic strength divided by 305. Now, when the size parameter of the ion, which is alpha is unknown, we're gonna use instead the Davies equation now here because of the lack of a size parameter, this formula is most useful for mono valent ions. So ions with a charge of one plus or minus. So examples would be sodium or chloride ion. Now you could also use larger charges but it tends to be greater deviation um from credible value but you can still use larger charged ions as well. So here the equation is reformatted into log of activity coefficient equals negative 0.51 Z squared times the square root of your ionic strength divided by one plus your square root of ionic strength minus 10.3 times your ionic strength here we have our ionic strength values, they're increasing as we go down here, we have our charges plus or minus one plus or minus two plus or minus three and our activity coefficients notice that as your ionic strength is increasing, your activity coefficients are decreasing. Now we're going to say here from the Davis equations, all ions with the same magnitude in charge. So if two ions, one is plus one and the other one is minus one or plus two and minus two, they will have the same activity coefficient, which is what we're seeing here. Okay, so plus or minus, it really doesn't matter. And again that's because of the lack of an alpha value. We can group things together and make our list overall smaller. Traditionally when we're using the extended W huckle equation we segregate ions based on their charge as well as the value of their charge. Now that we've seen this attempt to do the practice question that's left here on the bottom of the page um Where were asked to determine what the activity coefficient is of calcium ion. When we have 0.25 Mueller of calcium phosphate here, we don't have the active, we don't have the size parameters so we're not gonna be able to use our typical extended W huckle equation. So try this question out if you get stuck. Don't worry, come back and see how I answer the same question

So remember when we talked about acids and bases reacting with one another, they helped to create water and assault that salt represents an ionic compound that's composed of a positive ion which is our cat ion and a negative ion which is our an ion. Remember based on the identities of these ions we can make either an acidic basic or neutral solution. Now we're going to see through the creation of these ions. How does ph play a factor on their cell viability? So if we take a look at cat ions which are positive ions, remember they're grouped as transition metals, main group metals as well as positive means remember for transition metals they have to be plus two or higher in charge to be acidic. If they're less than plus two then they are neutral. Here we have manganese, five iodide And we have five iodide. Remember we're only concerned with the positive ion for now since its transition metal with a charge of plus two or higher it is acidic. The main group metals they have to be plus three or higher in charge to be acidic. If they're less than plus three then they would be neutral. Here we have aluminum fluoride, aluminum and group +38. So it's plus three and then we have our three fluoride ions because aluminum is plus three it is high enough that it is acidic. Finally remember positive amines are automatically acidic here we have methyl ammonium ion as our positive ion and we have quarried i on this would be acidic. Now how does this tie into some liability and ph well we're gonna say remember cat ions make either an acidic or basic or acidic or neutral solution, we're gonna say here, if we increase if we're increasing the sai ability, that's a direct result of increasing your ph So if you make the solution more basic, it makes your acidic salt more soluble. That's because if we think about it, let's say we have here, Aluminum three plus that is acidic ion. An acidic ion would help to form acidic ions in solution. If I increase the ph that means I'm adding O H minus O H minus here is going to eat up this H plus ion and decrease its amount. If we decrease that amount according to the chandeliers principle, our reaction to shift to the right in order to replenish the ion that we just lost. So that's how the identity of our ionic salt can be affected by the presence of our ph. Now that we've seen. Can ions click onto the next video to look at and ions

now for an ions we're gonna say here for an an eye and we're gonna add H plus ion to it. If you add an H plus ion to an an ion and you create a weak acid then your negative ion is basic. Here we have sodium nitrite nitrite ion is our negative ion. We add an H Plus to it to give us nitrous acid. Nitrous acid is a weak acid because it's a weak acid. That means that the negative ion is basic. If we add an H plus ion to the an ion and you create a strong acid though that means your negative ion is neutral. Here are negative ion in potassium chloride. Is the chloride ion add an H plus two. It gives us hcl. Now each sales a strong acid. And remember if you're strong as an asset that means you're conjugate base is incredibly weak. So weak that we just say that you're neutral. Now how does this tie in a solid ability? And ph again remember and ions are basically neutral here to increase the survivability of a basic ion. We want the solution to be acidic. So we want decreasing the ph because remember what's happening here is uh an eye on that is basic would react with water. And because it's basic that means water work as would act as an acid and donating H plus to the basic ion here we would get this plus O. H minus if you decrease the ph of a solution that means that you're making it more acidic by adding H. Plus that H Plus would actually counteract or neutralize this O. H minus or losing product. And according to the on the shuttlers principle to replenish that ion we'd have to move in the forward direction to make more. This means that more of this ion would have to break up in order to form that product and thereby increase the susceptibility of that particular ion. So remember for acidic salts we want to make the solution more basic to make it more soluble for basic salts. You want to make the solution more acidic to increase reliability. And remember for an esoteric species we have our acidic Amfa Terek species and our basic Amfa Terek species, they themselves also follow the same type of guidelines. Since they're acidic. You would want to increase the ph to make it more basic in order to increase their suitability. And these guys which are basic, you'd want to decrease the ph to make it more acidic and thereby increase their suitability.