ASAP - titration - rinsing equipment question (1 Viewer)

[amdspotter]

what do you rinse the burette and pipette with, also why do we wash the conical flask which holds the analyte initially with dimin water (distilled water) and then finally with the solution it was holding. also by finally it would have both analyte and the titrant being used so what do you wash it with.
thanks in advance

 

[icycledough]

1) The burette should be rinsed with distilled water first, then the titrant at the end (solution which does into burette) to not affect concentration

2) Similarly, the pipette should be rinsed with distilled water first, then the indicator which will be transferred from the pipette (I think some textbooks may just include rinsing with the solution going to be used, rather than BOTH distilled water and the solution, so I'm not 100% sure on that)

3) I think conical flask or other equipment is washed with distilled water then solution as distilled water cleans the equipment of any pre-existing liquid on the sides, which can affect the concentration. However, then it would have to be washed with the solution, to once again prevent affecting the true concentration

 

[CM_Tutor]

Do NOT under any circumstances wash the conical flask with anything but water. The calculations are based on the assumption that the analyte in the conical flask all came from the pipette. Concentration does not matter in the conical flask but moles does. The pipette must be rinsed last with the solution it is to deliver as concentration matters and any residue of water would dilute the sample. Adding water to the conical flask doesn't matter as we know the volume it occupied in the pipette, so if it is then diluted, it won't matter... so long as no extra is added.

 

[ColdMint123]

A good way to remember whether to wash with water or solution is;

all long and narrow things get washed with the solution going in them (eg. your pipette and burette, which are long and narrow)
all containers that have a wider base such as your conical flash and volumetric flask get washed with distilled water.

Good way to remember, but i suggest you also understand why for example, the pipette needs to be washed with the standard solution.

 

[amdspotter]

thanks a lot @icycledough @CM_Tutor @ColdMint123 really appreciate the time you have taken to help me understand this concept