I'm in 10th grade and we did a titration lab; with every lab we have to answer follow up questions and I'm totally stuck on this one: We did not uses the volume of the water added initially to the Erlenmeyer flask in our calculations. Why?
Ok as far as calculations go, I'm not even sure if I did them right and I just do what my teacher/the book says to do without question so I have no idea why I didn't use the volume of water in the flask for the calculations. Is it just because they were irrelevant? Sorry if this made no sense, it's due tomorrow so any help is greatly appreciated!
It isn't irrelevant and it makes a lot of sense. I have been asked this dozens of time in class and many students wonder how the volume of the water added makes no difference. Two ways to explain it. The most scientific way is this way. Say we titrate 25 mL 1.0 M acid with 25 mL 1.0 M base. What usually happens is that we start with 25.0 mL acid, add some water (not measured of course), add a few drops of indicator solution, then begin titrating with the base. You probably remember that as the end point came closer and closer the person washed down the sides of the flask with MORE water (again not measured) because we don't want drops of acid or base on the walls of the container. Here is why it doesn't matter. Scenario 1.
You have 25.0 x 1.0 = 25 mols of the acid to start. The indicator will turn when exactly 25.0 mL of 1.0 base has been added. It turns when the solution is neutralized. Adding water does nothing to make that neutralization happen. So the indicator is waiting until mols acid = mols base at which point it will change color (at least it will if the equivalence point and the end point are the same.) Got it. The end point is when mols acid = mols base and adding water doesn't change that.
Scenario 2 and the one that ALWAYS works with students but it's a little less scierntific.
OK. We've added 25.0 mL of 1.0 M acid to the flask and we add some water before the titration begins. The student asks, "But won't that dilute the acid?" And my answer always is, "Yes, but it will dilute the base (when it is added) exactly the same amount." I hope this helps.
Yes that makes a lot of sense now! Thank you so so much!:)
determine the specific heat capacity of a sample of zinc that weighs 187.2 grams if its temperature is changed from 22.0C to 35.0C when it absorbs 949 J of heat.
In a titration lab, the purpose is to determine the amount of a particular substance in a solution by reacting it with a known concentration of another substance. Typically, you would have a burette containing a solution of known concentration (the titrant) that you add drop by drop into a flask containing the solution of unknown concentration (the analyte) until the reaction is complete.
In this scenario, the volume of water initially added to the Erlenmeyer flask is not relevant to the calculations because it does not contribute to the reaction. The water is only used as a solvent to dissolve the analyte and provide a medium for the reaction to occur.
The calculations in a titration lab usually involve determining the volume of the titrant needed to reach the equivalence point, which is the point at which the reaction is complete. From this volume, you can calculate the concentration of the analyte using stoichiometry and the known concentration of the titrant.
To make sure you have done the calculations correctly, you should check the procedure given by your teacher or in the lab manual. Make sure you followed the steps correctly and used the appropriate formulas and conversion factors. It's also a good idea to ask your teacher or a classmate for help if you're still unsure.
Remember, understanding the reasoning behind the steps in a lab and the calculations involved is crucial for gaining a deeper understanding of the concepts and being able to apply them in different situations.