Question

0.90 gm. of a solid organic compound
(molecular weight = 90) containing C, H and O
was heated with oxygen having volume 224 ml.
at NTP. After the reaction, total volume of gas-
ses was 560 ml. at NTP. On treatment with
KOH, the volume decreases to 112 ml.
Determined the molecular formula.​

Answer 1

Explanation:

Number of moles of organic compound is = 0.9/90 = 0.01 mol

After KOH treatment volume CO2 decreased = 560-112 = 448 ML

It means the volume of CO2 produced is 448 ml

22400 ml of CO2 = 1 Mol of CO2 at stp

So 448 ml contains = 448/22400 = 0.02 mol

0.01 mol of organic compound produces 0.02 mol CO2

So 1 mol organic compound produce = 0.02/0.01 = 2 mol CO2

So number of C in the organic compound is 2

So the molecular formula C2HxOy 24+ x1 + 16 y = 90

Substitute some possible values gives x =2 and y = 4

Hence the molecular formula is C2H2O4