RP 2- acid base titrations Flashcards
what is the aim of this practical?
to determine the concentration of hydrochloric acid
what is the first part of this practical? (7)
1) making standard solution of NaHCO3
2) weigh out a certain mass in a weighing boat and transfer into 250cm3 beaker
3) add a small volume of distilled water into the beaker and stir until fully dissolved, swill out weighing boat
4) transfer solution into 250cm3 volumetric flask using a funnel
5) rinse the beaker and glass rod and funnel with distilled water to the volumetric flask
6) fill volumetric flask up to graduated line using distilled water
7) stopper the flask and invert a few times
what is the second part of this practical? (6)
1) Finding the concentration of HCl by titration
2) use pipette and pipette filler to transfer xcm3 of the standard NaHCO3 solution to a 250cm3 conical flask
3) fill the burette with hydrochloric acid (ensuring there is no air bubble) and record initial burette reading
4) add HCl from burette to conical flask and add drop wise as you near the end point (change from yellow to orange)
5) record final burette reading
6) repeat until 2 concordant results are obtained
how do we calculate the concentration of HCl?
1) calculate the mean tire using only concordant results
2) calculate moles of NaHCO3 present in 25cm3 of standard solution
3) calculate moles of HCl present in the mean titre using neutralisation equation
4) calculate concentration of HCl
what are the errors in this experiment?
1) some of the weighted NaHCO3 may not be transferred from the weighing boat
2) forcing all liquid from pipette
3) colour change may not be clearly visible during titration