Strong Acid-Strong Base

Jules Bruno
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So let's take a look here. He says calculate the pH of the solution resulting from the Thai Trey Shin off 75 miles off 750.100 Moeller H b R 04 with 55 Emil's off 550.100 Mueller N A N h. Two. So remember this right here is a strong acid. This right here is a strong base. So what we're gonna say here is because both are strong. We don't have to use a nice We don't have to use a nice CF. So what are we doing? Step? We're gonna say step one is find the moles. And remember, how do we find moles? Remember, moles equals mole arat e Times leaders so divide the MLS by 1000. Multiply them times their lead on their mole Aridjis. Now, remember, for the base for the base, you're always supposed to check how maney O H minus is and H two minuses. H minus is an O to minus is you have to get the correct concentration. Here. We only have one NH two. So we don't have to worry about multiplying the concentration by anything. We can keep it as it iss So when we do this, we're gonna say 0.75 liters. Times 0.100 Moeller h b r equals 0075 moles of H B R 04 Then we do the same thing with the other one. Okay, so we have that. Now that we found their moles, we're gonna subtract the larger one by the smaller one. So what you're gonna say is now you have this much left off your strong acid. Okay, so that's all you're gonna say. That's how much you have left of your strong acid. Now, step two, you're gonna find mole arat e off whatever you have left. And how do we find polarity? Well, we're gonna take the moles that we just found and divide them by the total volume. So those two leaders added up together will give you my total volume. So we're gonna say 0.20 moles of H b R 04 divided by the total volume we used 0.75 liters plus 0.55 leaders. When we divide those together, that's going to give me 0.154 Mueller h B R 04 And remember, Since this is a strong acid to find pH, we don't need to do a nice chart since the strong acid just take the negative law. Negative log of a strong acid will give me my pH. Okay, so we plug in the concentration here, and at the end, he's scroll up some at the end. What is that gonna give me? My pH will be 1. So it's a simple is that if both their strong, this is a great situation. First, find the moles of both and remember, look at the correct morality of the strong base. If you have to multiply by two because there's 20 H is or there's two NH twos or there's two h is h minus is then you do that before you change everybody into moles. Once you find moles, you subtract the larger moles from the smaller moles. Whoever is left behind, whether it be a strong acid or strong base, you immediately change it into molar ity. If you have the polarity of a strong acid, take the negative log to find pH. If you have the polarity of a base a strong base. Then take the negative log of that. But that will give us P O. H. So remember strong basis if you take the negative log, gives us p o H. If you have P o h, you're gonna take that answer that you find and subtracted from 14 and that will give you pH. So it's a simple is that Just remember the steps. Step one. Find moles. Step to find polarity. Step three. I guess you just take the negative log or whatever your answer is to find either pH or P O. H. And that's all you really have to do. There's no need of any type of chart now that we've done this one. I want you guys to attempt to do the next one on your own as practice. So just take the same methods that we used above in order to find it. Make sure you get the correct concentrations of everyone before you change everyone in two moles. As long as you can remember that you'll be able to solve this question. Good luck, guys.