
	Trending ▼ ICSE CBSE 10th ISC CBSE 12th CTET GATE UGC NET Vestibulares ResFinder

ISC Class XII Analysis Of Pupil Performance 2014 : Chemistry

9 pages, 10 questions, 0 questions with responses, 0 total responses,

	Prateek Gurjar Kabul	+Fave Message
	Profile Timeline Uploads

Home > prateekgurjar > F Also featured on: School Page

Formatting page ...

CHEMISTRY PAPER 2 (PRACTICAL) Attempt all questions. Question 1 [8] You are provided with two solutions as follows: C-10 is a solution prepared by dissolving 25 gms of sodium thiosulphate crystals (Na2S2O3 xH2O) per litre. C-11 is a solution prepared by dissolving 5 gms of potassium dichromate (K2Cr2O7) per litre. [ PROCEDURE: Rinse and fill the burette with the given solution C-10 (Na2S2O3.xH2O). Pipette out 20 ml or 25 ml of solution C-11 (K2Cr2O7) in a clean conical flask. To this, add 20 ml of C-12 (dilute sulphuric acid) and about 20 ml of C-13 (10% solution of potassium iodide). Now add about 20 ml of distilled water, followed by a pinch of sodium hydrogen carbonate (C-14). Shake the contents of the flask and cover it with a watch glass. Allow the solution to stand for about 5 minutes till the solution becomes dark reddish brown. Titrate the solution by running C-10 from the burette till the solution turns yellowish green. Add about 2 to 3 ml freshly prepared starch (C-15). The colour of the solution changes to dark blue. Continue adding C-10 drop-wise till addition of one drop of C-10 changes the colour of the solution from blue to light green. Repeat the above procedure of titration to get at least two concordant readings. Tabulate your readings. State: (a) The capacity of the pipette used. (b) The titre value you intend to use in your calculations. Show the titre value to the Visiting Examiner. The equations for the above reactions are as follows: K2Cr2O7 + 7H2SO4 + 6KI 4K2SO4 + Cr2(SO4)3 + 7H2O + 3I2 6Na2S2O3 + 3I2 3Na2S4O6 + 6NaI. Cr2O 72 + 14H+ + 6 I 2Cr3+ + 7H2O +3I2 6S2O 32 + 3I2 3S4O 62 + 6 I Relative atomic masses: K =39 Cr = 52 Na = 23 S = 32 O = 16 56 H=1

Formatting page ...

Additional Info : ISC Class XII Analysis Of Pupil Performance 2014 : Chemistry
Tags : ISC Board, Class 11th, Class 12th, NDA/NA Entrance Examination

prateekgurjar chat

Horizontal lines at:
Guest Horizontal lines at:
AutoRM Data:
Box geometries: