Write balanced net ionic equations and the corresponding
equilib...

Question

Write balanced net ionic equations and the corresponding 
equilibrium equations for the stepwise dissociation of the 
triprotic acid H3PO4.

Accepted Answer

hi everyone for this problem, it reads citric acid is a week try protic acid, right balance dissociation equations and corresponding equilibrium expressions for each dissociation step. So what we want to do here is we have two things we want to do. We want to write balanced association equations of course and corresponding equilibrium expressions. Okay, for each step. And let's take a look at that week, the acid that we're working with which is citric acid and this is a weak acid. Any weak acid dissociates like this. So we have the weak acid reacts with water and it's at equilibrium to produce hydro ni um ions plus the conjugate base and the equilibrium expression for this. It's not going to have the water in it because we don't include pure liquids and solids and the equilibrium expressions. And so the equilibrium expression becomes the concentration of products over the concentration of reactant since but in this case we just have our weak acid as the reacting. So let's take a look at our citric acid. Okay? And we're gonna go ahead and start off with writing the first dissociation. Okay, there are three car box cilic groups in citric acid. Since we're not concerned with the individual P. K. A values of the three car box silic acid values, we can write an equation where we will remove a proton from any of the three carb oxalic acid groups. So something that will need to remember is that if we had individual P. K values we would have removed proton from the carb oxalic acid group that had the smallest P. K. A. Value and the carb oxalic acid with the largest peak a value would lose the proton last. So let's go ahead and write our first association step. Okay, so this is our first step and our equilibrium constant expression. Then it's going to be our concentration of products over our concentration of reactant and we're not going to include any solids or liquids. So then this becomes okay, so this is our first association along with its equilibrium constant. Okay, so the second dissociation is going to be okay and the K expression or the Yes, the equilibrium constant expression, it's going to be the concentration of products over the concentration of react ints. And lastly the third dissociation along with its K expression or equilibrium constant expression is going to be the following. Oops, that is not correct. Excuse me. So we have and the constant for this one. K A three. This one is K two and the first one is K A one. Okay, so K three R equilibrium constant expression for the third one is concentration of products. Yeah. Okay, so that is going to be the answer to this problem. The 1st 2nd and 3rd associations along with their equilibrium constant expressions. Okay, that is it for this problem. I hope this was helpful

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