Chemistry

posted by .

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!

• Chemistry -

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.

• Chemistry -

Yes that makes a lot of sense now! Thank you so so much!:)

• Chemistry -

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.

Similar Questions

1. Chemistry Titration Lab HELP!

Hi everyone! I just got a new lab that I MUST complete today, and it's about titration- I have absolutely no clue how to do it, it just doesn't make sense to me! I hope that someone can help explain to me how to do it so I can finish …
2. Chemistry

I did a lab in which I added ionic solutions to tap and distilled water and another ionic solution. Distilled water is the control because it does not react to any solutions since it doesn't contain ions. But one of the lab questions …
3. 11th grade CHEMISTRY TITRATION LAB!

i have a tritation lab due tomorrow and i am stumped on a couple things. its a titration lab using sodium hydroxide (NaOH)- 250 mL 0.300 M concentration, 10 mL of an unknown substance of vinegar, the avg. of titrated NaOH in the flask …
4. Honors Chemistry

We did a lab in class on Friday where we stuck a metal loop in various chemicals and stuck it in the flame of a Bunsen burner and we observed the flame's colors as the different metals went in. For every lab we do, we have to write …
5. chemistry

I did a lab on pressure and depth today. This lab was to simply submerge a plastic tube into a large graduated cynlinder to find the relationship between the two. I found that as the depth increases, so does the pressure. One of the …
6. Chemistry Titration Lab

We did not use the volume of the water added initially to the Erlenmeyer in our calculations. Why?
7. Science 7R (Lab questions)

We did a lab today at science and for homework we have to answer questions about the Lab. I need help on 2. 12. Name two ways that a plant and animal cells differ in structure?
8. Chemistry

I'm doing some post lab questions and I'm stuck on one. In lab we performed Tollens test, Fehlings test, and Jones Oxidation to differentiate our unknown between an aldehyde or a ketone. The question I'm stuck on is " older bottles …
9. Chemistry

Sorry to post again but I'm really stuck on this one! I'm doing some post lab questions and I'm stuck on one. In lab we performed Tollens test, Fehlings test, and Jones Oxidation to differentiate our unknown between an aldehyde or …
10. Chemistry

1. Imagine that you work at a company that prepares chemical solutions. You are asked to label a solution to sell to different customers. One customer is a hospital, another is a chemistry lab at a university, and a third is a physics …

More Similar Questions