SELECT * FROM question_mgmt as q WHERE id=667 AND status=1 SELECT id,question_no,question,chapter FROM question_mgmt as q WHERE courseId=3 AND subId=9 AND chapterId=60 and ex_no='1' AND status=1 ORDER BY CAST(question_no AS UNSIGNED)
Why is it essential to wash the precipitate with water before estimating it quantitatively?
The precipitate (product) formed out from any chemical reaction always contains some traces of unwanted materials (unreacted reactants or catalyst and certain impurities). These unwanted materials adsorbed onto the surface of the required product and settle down at the bottom of the container. For quantitative estimation of the product, these unwanted materials has to be removed. For removal of unwanted materials, different methods are used, one of them is washing with water. Because most of the impurities are water soluble, so they can be easily removed from the product. Water easily makes hydrogen bond with most of the elements (polar). After washing with water, the unwanted materials gets dissolved in water and removed out from the final product.
The following results have been obtained during the kinetic studies of the reaction: 2A + B → C + D
Experiment |
A/ mol L - 1 |
B/ mol L - 1 |
Initial rate of formation of D/mol L - 1 min - 1 |
I | 0.1 | 0.1 |
6.0 × 10 - 3 |
II | 0.3 | 0.2 |
7.2 × 10 - 2 |
III | 0.3 | 0.4 |
2.88 × 10 - 1 |
IV | 0.4 | 0.1 |
2.40 × 10 - 2 |
Determine the rate law and the rate constant for the reaction.
Vapour pressure of pure acetone and chloroform at 328 K are 741.8 mm Hg and 632.8 mm Hg respectively. Assuming that they form ideal solution over the entire range of composition, plot ptotal' pchloroform' and pacetoneas a function of xacetone. The experimental data observed for different compositions of mixture is.
100 ×xacetone |
0 | 11.8 | 23.4 | 36.0 | 50.8 | 58.2 | 64.5 | 72.1 |
pacetone /mm Hg |
0 | 54.9 | 110.1 | 202.4 | 322.7 | 405.9 | 454.1 | 521.1 |
pchloroform/mm Hg |
632.8 | 548.1 | 469.4 | 359.7 | 257.7 | 193.6 | 161.2 | 120.7 |
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