50   10. a weak acid with an initial ph of 3.2 was titrated with a strong base. 15 ml of 0.1 m naoh was added to the acid to reach the equivalence point at a ph of 8.6. what would you expect the approximate ph of the analyte to be after the first 5 ml of 0.1 m naoh was added? 8.6 3.4 5.1 7.2

Answer : Option C) 5.1

If we consider any weak acid and strong base titration. We usually observe that the pH initially rises quite fast then remains constant during the buffer region before rising rapidly to the end point.

So, if 5 mL of NaOH is considered to be the one third of the way to the endpoint, then after the initial rise which will be more than 3.4 and reaching to the buffer region before rising to the endpoint.

Now, if endpoint has pH of 8.6 a buffer region around 5 is a good but the acid could be acetic acid which has similar pH endpoints with the pKa of 4.74 - so buffer region around 5 will be the good condition.

And hence pH of 5.1 is the most probably the right answer.

5.1 would be the clostest answer

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).