# 11th grade CHEMISTRY TITRATION LAB!

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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 with vinegar is 27.7 mL

firstly its a titration lab where the purpose is determining the concentration of a acetic acid in an unknown sample of vinegar.
to begin..i have no idea what to write for the hypothesis. we added phenolphthlein so we have to reach an end-point.

secondly, i do not know what the balanced chemical equation would be. the only known substance is sodium hydroxide (NaOH) and vinegar but i don't know what kind.

and how do i calculate the concentration of the substance using avg volume?

thank you so much if you can help!

• 11th grade CHEMISTRY TITRATION LAB! -

I am somewhat confused but I can answer most of your questions. Vinegar is acetic acid and you are doing th titration in order to determine the concentration of acetic acid in vinegar. Acetic acid is HC2H3O2 and the first H on the left in the formula is the acidic hydrogen (the other H atoms in the formula don't contribute to the acidity). So here is the equation.
HC2H3O2 + NaOH ==> NaC2H3O2 + HOH which follows the general rule that acids plus bases produce a salt (in this case sodium acetate) plus water.
Next, the concentration is determined by the following:
How many mols NaOH were used in the titration? That will be M x L = 0.3 M x 0.0277 L = ?? mols.
Since there is 1 mol acid to 1 mol NaOH in the balanced equation, that tells you the mols acetic acid in the sample is equal to the mols NaOH in the titration which you have just calculated. If you want concentration of the acetic acid, it will be mols/L. You have mols and the volume of the unknown is 10 mL (0.010 L). Or if you want grams acetic acid in the sample, that is mols acetic acid x molar mass acetic acid = grams acetic acid.
Now you know grams acetic acid in the 10 mL sample of the unknown vinegar.

• 11th grade CHEMISTRY TITRATION LAB! -

oh ok..i just wasn't sure if the vinegar was acetic acid because the procedure saud determining the concentration of acetic acid in an unkown sample of vinegar.
thank you very much though!

oh one last question, i understand the purpose of lab and how to conduct the lab but im still not quite confident on what to write for the hypothesis. am i supposed to hypothesize on the concentration of the vinegar? but i don't know what logical assumptions i would use to prove my point

• 11th grade CHEMISTRY TITRATION LAB! -

I don't know exactly what you are doing so I'm not sure of a hypothesis. You may have hypothesized that the concn of the vinegar was xx percent (most is 4% or 5%) or you may have hypothesized that the vinegar purchased at some location was not as strong as it should have been.

• 11th grade CHEMISTRY TITRATION LAB! -

alright thank you very much i appreciate it! :)

• 11th grade CHEMISTRY TITRATION LAB! -

weiirrdd .. i'm in grade 11 with a titration lab due the same day
and i had the same questions .. i never handed it in today so i get 5% off . but what did you end up writing for your purpose and hypothesis ?

• 11th grade CHEMISTRY TITRATION LAB! -

can someone just come to my house and do my lab for me????

• 11th grade CHEMISTRY TITRATION LAB! -

dvdx

• 11th grade CHEMISTRY TITRATION LAB! -

it is easy to know it and i am only in year 10

• 11th grade CHEMISTRY TITRATION LAB! -

how do you do the concentration of the unknown base?

• 11th grade CHEMISTRY TITRATION LAB! -

Well, firstly the Purpose is to dtermine the concentration of the acetic acid in a vinegar sample.
And the hypothesis is just writing what you think the concentration of the acetic acid in vinegar might be.

• 11th grade CHEMISTRY TITRATION LAB! -

Well, firstly the Purpose is to determine the concentration of the acetic acid in a vinegar sample.
And the hypothesis is just writing what you think the concentration of the acetic acid in vinegar might be.

• 11th grade CHEMISTRY TITRATION LAB! -

bigboy

• 11th grade CHEMISTRY TITRATION LAB! -

what ate the assumption of the titration lads

• 11th grade CHEMISTRY TITRATION LAB! -

idk

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