Titration help!! (1 Viewer)

[yayyy]

i am confused about the procedures for conducting an accurate tiltration

- why do we need to rinse the burette with distilled water first, then with the solution to be held in it later? whereas for the conical flask, only distilled water is required???

thanks!!

 

[b3kh1t]

i am confused about the procedures for conducting an accurate tiltration

- why do we need to rinse the burette with distilled water first, then with the solution to be held in it later? whereas for the conical flask, only distilled water is required???

thanks!!

It must first be washed with distilled water to remove any dirt and unwanted substances. It must then be washed out with the solution you will put into the burette as this will remove the distilled water remaining in the it, this must be done as if some distilled water remains then the solution will become more dilute and your answer will not be valid or reliable. However, the conical flask (assuming this is where you will put the solution to be titrated) can be washed with distilled water as the indicator will be put in here, if you wash this flask with the solution, you will either increase the amount of hydrogen ions or hydroxide ions therefore altering the amount of the solution needed to neutralise it.

 

[FaDeYagami]

I think i might help although i did terrible for my titration prac test ><
The reason u have to wash with distilled water first is to eliminate any substances that might contaminate ur solution later. U have to re-rinse with the solution that will go into it later abt 3 times to make sure every drops of liquid left in the burette after washing will not affect the concentration of the solution will be held in it. If u just wash with water, the concentration later will be lower than wat u want coz u somehow dilute it with the water left. The conical flask is different, say when u add 20mL of 1mol/L NaOH into it, because this is already measured carefully by you, there will be exactly 0.02 mol in the conical flask, then the number of moles of the unknown needed to neutralise that 0.02 mol is the same the concentration doesnt really affect it

 

[effylove]

^what b3h..etc. said

Don't forget.
The first titration is disregarded and you don't include it when averaging.
It's only meant to be a rough indication.

 

[b3kh1t]

^what b3h..etc. said

Don't forget.
The first titration is disregarded and you don't include it when averaging.
It's only meant to be a rough indication.

That is generally true however if the titration for the first one is close to the others then it should be included, the difference must be within 0.1 from memory, and then you discard the rest

 

[effylove]

That is generally true however if the titration for the first one is close to the others then it should be included, the difference must be within 0.1 from memory, and then you discard the rest

psh
easier to do it the normal way.

 

[muzeikchun852]

I doubt they will ask it again, since they asked a 7/8 marker last year.

 

[b3kh1t]

Lol aiight just putting it out there

I doubt they will ask it again, since they asked a 7/8 marker last year.

nah they have to ask something about it, but maybe not a big question like that and it wouldn't hurt to know the stuff

 

[yayyy]

thanks guys!! i reckon the chemistry paper this year will not easy and requires a lot of analytical thinking.. so better to know everything. like maths ex1..

 

[FaDeYagami]

man are they changing the syllabus for chem next year?? coz if they do then they will make this year chem paper just as cruel as maths ext 1