Question 10

[li5504552]

I am confused how it is known that 4.6 is equivalence point because we cannot tell when the moles of acid are equal to moles of base as we do not have the concentration of the base. Thanks.

[admin]

Once you have the graph then you can tell where the moles of acid is equal to the moles of base: it is given by the point of inflection of a titration curve (the point at which the curve essentially is changing directions; sometimes referred to as the midpoint of the straight part of the curve).

CHM 6.9

Take a look at these curves: www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html

[MANDALAM]

HI,

ONCE YOU HAVE THE GRAPH IT IS PRETTY EASY. HOWEVER, IN THE QUESTION THE GRAPH IS NOT GIVEN, AND I TRUST WE ARE NOT SUPPOSED TO ASSUME THE GRAPH IN QUESTION 8 IS THE ACCURATE GRAPH FOR QUESTION 10 WITHOUT THE QUESTIONS MENTIONING SO. AND I DON'T THINK THE TABLE GIVES ANY INDICATION OF THE EQV. POINT. IS THERE ANY OTHER WAY TO FIND THIS, THAT WE NEED TO BE AWARE OF?

THANK YOU.

[dnpgr16513]

PLEASE CLARIFY...THERE WAS NO GRAPH GIVEN EXCEPT IN THE QUESTIONS WHICH SHOULDN'T ALLOW US TO BASE OUR ANSWER OFF OF THAT.............................................

[mopilas1171]

There are no graphs present in this passage...and I don't get how we're suppose to assume that 15mL is the equivalence point. Thanks

[hua8986059]

ya this question was kind of hard, can't use graph based from question I would think.

But I guess we kind of know that going from PH of 8.8 to 4.4 would indicate that this was a drastic change in PH therefore this was a end point (inflection) point.