A particular oral contraceptive contains 0.038 mg of ethinyl estradiol in each pill. The formula of this compound is C20H24O2. How many molecules of ethinyl estradiol are there in one pill?

The number of molecules of ethinyl estradiol present in one pill are

Explanation:

To calculate the number of moles, we use the equation:

Given mass of ethinyl estradiol = 0.038 mg =    (Conversion factor: 1 g = 1000 mg)

Molar mass of ethinyl estradiol

Putting values in above equation, we get:

According to mole concept:

1 mole of a compound contains number of molecules

So, of ethinyl estradiol will contain = number of molecules

Hence, the number of molecules of ethinyl estradiol present in one pill are

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

they are all solids.