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The cryoscopic constant for acetic acid is 3.6 K kg/mol. A solution of 1g of a hydrocarbon in 100 g of acetic acid freeze at `16.14^(@)"C"` instead of the usual `16.60^(@)"C"`. The hydrocarbon contains 92.3% carbon. What is the molecular formula? |
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Answer» Correct Answer - `C_(6)H_(6)` Hydrocrabon-B ,acetic acid-A `"m"_("B")=(1000"K"_("f")"w"_("B"))/("w"_("A")xxDelta"T"_("f"))` `=(1000xx3.6xx1)/(100xx(16.60-16.14))` `"m"_("B")=78 "gm"` let molecular formula of Hydrocarbon`="C"_("x")"H"_("y")` `12"x"+"y"=78` `implies(12"x")/(78)xx100=92` `implies" x"=(92xx78)/(12xx100)` `"x=6(App)"` `"y=6"` `therefore"Molecular formula of compound"-"C"_(6)"H"_(6)` |
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