Assume that you have 1.00 g of a mixture of benzoic acid (Mol. wt. = 122) and gallic acid (Mol. wt. = 170)), both of which contain one acidic hydrogen that reacts with NaOH. On titrating the mixture with 0.500 M NaOH, 14.7 mL of base is needed to completely react with both acids. What mass in grams of each acid is present in the original mixture?

Video transcript

Hello everyone today. We have the falling problem. A mixture containing a mixture contained lactic acid and Peruvian acid. Both acids contain one acidic hydrogen that reacts with potassium hydroxide. How much of each acid in g is in the mixture of 297 ml of 45 molar potassium hydroxide Is required to completely react with .150 g of the mixture. So it was stated that both acids, So both acids contain only one acidic hydrogen, Right one H. Plus There is a 1-1 Mole ratio with the acid-based filtration. So for every one asset there is one mole of base. And so in this titillation we have moles of lactic acid and we also have moles of piru vic acid. So most of lactic acid, animals of piru acid. And so what we need to do is we need to find the moles of our potassium hydroxide that we are going to use to titrate this mixture. So we want to we want to take the 297 ml of our potassium Hydroxide. You want to convert that to leaders by using the conversion factor, that one leader is equal to 1000 ml. And we want to multiply by our molar itty similarities and units of moles per liter. So you can simply say this is 45 moles for one liter. When our units canceled out, we end up with 13.3 moles of potassium hydroxide. No, but the thing that we need to do is we need to set up some variables to solve for our mass. So if we let X equal the mass of lactic acid. So the massive lactic acid is in grams, then we can say that the mass of our piru vic acid Is the total mass .150 g of the mixture minus whatever the value for X is. And so we set up an equation to solve for that variable. So we set up X, which is essentially our mass over R. Mueller mass for lactic acid, which is 90. plus We do the total mass minus the mass of lactic acid over the molar mass of Pirou vic acid, which is 88.06 g per mole. And we can go ahead and equal that two h 13.365 moles of potassium hydroxide. Because remember we have moles of lactic acid and peru vic acid that make up this mixture. And we also said that when we have a 1-1 more ratio that is the situation here. So, and solving for X, We get the answer that X is equal 0.077- grams of course. And so we said that the mass of our lactic acid was X. So our mass of lactic acid is going to be that 0.077 - three g. And our mass of our Peruvian acid Is going to be the total mass of the solution, 0.150 g minus the mass of our lactic acid. And that is going to give us 0.0778 g as our answer. And so we have our two masses found here. Overall, I hope that this helped, and until next time.