Posted by **Mary** on Saturday, April 14, 2007 at 11:01pm.

The active ingredient in the allergy medication Claritin contains carbon (C), hydrogen (H), chlorine (Cl), nitrogen (N), and oxygen (O). Its molecular formula is C22H23ClN2O2. The standard adult dosage utilizes 1.480 1019 molecules of this species. Determine the mass (in grams) of the active ingredient in the standard dosage.

The molecular mass of the active ingredient is:

22(12.011) + 23(1.00794) + 35.453 + 2(14.0067) + 2(15.9994)= 382.88982u

Please tell me where do I go from here.

There are 6.022E23 molecules in 382.89 grams of this substance. A proportion should solve the problem for you. Is that a period between 1 and 4. Check the problem. I don't know how you will get 1.480 molecules. That is a VERY small number. And how will you divide a molecule so you can get exactly 1.480 of them?

Sorry that was my mistake. The correct number is 1.480 x 10^19.

That's much better. The method for any number however, is the same.

Thanks!