Errors!

[cindyy]

edit: solution X = HCl and solution Y = NaOH

Is this correct?

When the burette is rinsed with water:
The solution is diluted, which means more titre needs to be used to reach the end point, and the concentration of the solution will be lower.


When the pipette is rinsed with water:
The volume of the solution in the pipette will be less, therefore the titre to dilute the solution will be less, and hence the calculated concentration will be higher.

When the pipette is rinsed with solution:
The solution X will react with solution Y, which means less titre will be required to reach the end point, and the calculated concentration will be higher.

[Martoman]

I don't think so.

1) If its rinsed with water >> diluted >> more volume needed >> HIGHER percentage.

2) Diluted >> More titre >> HIGHER

3) If it reacts there will be less solution which means less needs to be added from titre which means lower.

I could be wrong i hate this stuff

[cindyy]

arghh we said the opposite! haha yeah, i hate this stuff too, confuses the shit out of me!

for the first one, i did it on my calc: i did 0.025/0.02 and 0.025/0.03, the second one being due to the error, and there was a lower concentration, thats why i thought it was lower. haha

[boysenberry]

Are you guys planning to memorise these?

[cindyy]

no...i would just like the understand it

[stonecold]

I don't think there a defined rules you can follow, as it entirely depends on what solution is in what glassware.  

[ghadz7]

Martoman is right! When less titre is required, it means there was a lower amount of the substance in the conical flask ( c = n/v ). Hence the concentration is lower.

[Martoman]

Yay my intuition!  :smitten:

[cindyy]

yay for you, not so yay for me! haha this stuff is so confusing.

so when there is more titre, it means higher concentration?

[ghadz7]

That's right.

[ghadz7]

Have you tried TSFX 2010?

[chansthename]

I don't think so.

1) If its rinsed with water >> diluted >> more volume needed >> HIGHER percentage.

2) Diluted >> More titre >> HIGHER

3) If it reacts there will be less solution which means less needs to be added from titre which means lower.

I could be wrong i hate this stuff

Wow, I'm really confused now too,

NB, I am going with a titration where the burette contains HCL and volumetric flask contains NaOH

First one, I agree with you (just think it should be higher concentration not percentage, volumetric not gravimetric)

2. Since we have some water in the pipette there is a lower concentration of NaOH going into the conical flask. as a result less HCl is required to reach an endpoint.
Lower titre -> lower mol HCl used in reaction -> lower mol of NaOH -> Lower calculated concentration of NaOH

3. not sure what the original question is saying.

If it is saying that the pipette is rinsed with NaOH (from my scenario) then there will be no change as that is what should be happening.

If it is saying the pipette is rinsed with HCl then some HCl and NaOH will react in the pipette, meaning less HCl from the burette is used to reach an endpoint. end result lower titre and lower calculated concentration.

Correct me if I am wrong (really confused now)

[ghadz7]

The solution X will react with solution Y. Hence the two solutions are different which indicates that HCl reacted with NaOH.

[simonhu81292]

Is this correct?

When the burette is rinsed with water:
The solution is diluted, which means more titre needs to be used to reach the end point, and the concentration of the solution will be lower.



When the pipette is rinsed with water:
The volume of the solution in the pipette will be less, therefore the titre to dilute the solution will be less, and hence the calculated concentration will be higher.

When the pipette is rinsed with solution:
The solution X will react with solution Y, which means less titre will be required to reach the end point, and the calculated concentration will be higher.

it depends where the sample is ... the flask, burette or pipette ...
so yeah... as stonecold said ... depends on the situation

[cindyy]

Okay, i guess this is all my fault, i thought it would be the same with all situations, so i didnt use any compounds, so lets say solution X is HCl and solution Y is NaOH!