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The first and second ionization constants of a diprotic acid $\mathrm{H}_{2} \mathrm{A}$ are $K_{\mathrm{a}_{1}}$ and $K_{\mathrm{a}_{2}}$ at a certain temperature. Under what conditions will $\left[\mathrm{A}^{2-}\right]=K_{\mathrm{a}_{2}} ?$
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Chemistry 102
Chapter 15
Acids and Bases
Liquids
University of Central Florida
Drexel University
Brown University
Lectures
03:07
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, a liquid is one of the four fundamental states of matter (the others being solid, gas and plasma). A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds. Water is, by far, the most common liquid on Earth. Like a gas, a liquid is able to flow and take the shape of a container. Most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, leading to wetting phenomena.
04:38
A liquid is a state of matter in which a substance changes its shape easily and takes the form of its container, and in which the substance retains a constant volume independent of pressure. As a result of this, a liquid does not maintain a definite shape, and its volume is variable. The characteristic properties of a liquid are surface tension, viscosity, and capillarity. The liquid state has a definite volume, but it also has a definite surface. The volume is uniform throughout the whole of the liquid. Solids have a fixed shape and a definite volume, but they do not have a definite surface. The volume of a solid does not vary, but the volume of a liquid may vary.
02:09
The first and second ioniz…
00:45
For a weak diprotic acid $…
01:07
02:21
Write the general equation…
okay for this problem. We're going to talk about dissociation constants for die Protic assets and were given in the following information. We have a die product acid H two A and we're going to call its dissociation Constant. Gonna write it over here, Actually read it down here as a dissociation. Constant one. Um and this is going to so to dissociate into a hydrogen ion and h a minus all of these air Equus and then this substance to a J minus will become for step two. I worked acid, and that will further disassociate into this again. These are all a quiz we have Step one and step two for the dissociation of a die product. Gas it and we'll call the dissociation constant for this one k A. To our question is the question that we're trying to answer is when, Under what conditions? When will the concentration of the eight to minus ion be equal to K A. To that's our question. Let's go ahead And writer dissociation constant expressions for each of these K one is going to be equal to We'll have our hydrogen ion on the top for the numerator and our H A minus in the numerator and our age to a concentration in the denominator for a second reaction will have its K two again H plus on the top, and this time we'll have a to minus in the numerator, and the denominator will have a J minus. So when will this quantity be approximately equal to that quantity? Let's look, we want to know when this quantity will be equal to this quantity. So that will be true when my age plus and my age A's when this quantity is equal to one, or when these are both approximately equal to one. More importantly, when this quantity is one. So let's look up here for our first step. We know that these two values are equal to one another. So if k a one, if K a one is substantially larger, then k a. To what will happen. That means that there's going to be very little these air going to be next to nothing. They're going to become insignificant because if K 81 is very much larger than K A. To this is the reaction that's most of your I'm hydrogen is and you're A J. plus will be present up here. The A J minus isn't going to furthered associate. So when K A one is quite a bit greater much greater than K A to then que a two will be equal to a two minus. Thanks for listening.
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