In 1934, Edward A. Doisy of Washington University extracted 3000 lb of hog ovaries to isolate a few milligrams of pure estradiol, a potent female hormone. Doisy burned 5.00 mg of this precious sample in oxygen and found that 14.54 mg of CO2 and 3.97 mg of H2O were generated.
(a) Determine the empirical formula of estradiol.
(b) The molecular weight of estradiol was later determined to be 272. Determine the molecular formula of estradiol.
Solution 54SP :
Amount of estradiol burned = 5.00 mg.
Amount of CO2 generated = 14.54 mg.
Amount of H2O generated = 3.97 mg.
Estradiol is a form of estrogen, a female sex hormone produced by the ovaries. It is essential for the development and maintenance of female reproductive tissues of organs.
(a) Determine the empirical formula of estradiol :
Empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound.
the empirical formula of disulfur dioxide is S2O2.
the empirical formula of ethane(C2H6) will be CH3.
Empirical formula gives the relative number of atoms of each kind present in that compound.
For example: Consider, Ethane (C2H6)
Relative number of atoms in simplest form will be CH3 and it is the empirical formula of ethane.
Steps to determine the empirical formula of a compound :
- First, we find the number of grams of each element. If percentages are given, we assume that the total mass is 100 grams so that the mass of each element = the percent given.
- Then, we convert mass of each element to number of moles.
- Then,we divide number of moles of each compound by the smallest number of moles calculated.
- Finally, we round up the obtained result to the nearest whole number and thus we get the mole ratio of the elements and this is represented by subscripts in the empirical formula.