AP EAMCET201825 Apr 2018Morning ShiftChemistrySolutionsActual
When 36 g of a non-volatile, non-electrolytic solute have the empirical formula CH 2 O is dissolved in 1 . 2 kg of water, the solution freezes at - 0 . 93 ° C . The molecular formula of the solute is ( K f of water = 1 . 86 K kg mol - 1 )
Options
- ACH 2 O
- BC 2 H 4 O 2
- CC 3 H 6 O 3
- DC 4 H 8 O 4
Correct answer
B. C 2 H 4 O 2
Step-by-step solution
Given, Mass of the solute = 36   g Mass of the solvent = 1 . 2   kg ∆ T f = Depression in freezing point = 0 . 93 ° C K f H 2 O = 1 . 86   K   kg   mol - 1 We know that, ∆ T f = K f × m Molality, m = Mass   of   solute Molar   mass   of   solute × mass   of   solvent   kg ⇒ m = 36 M × 1 . 2 Substituting the values, we get, ⇒ 0 . 93 = 1 . 86 × 36 M × 1 . 2 ⇒ M = 60 Given, Empirical formula = C