Question

Three frequently prescribed antihypertensive medications are:

a) lisinopril (C₂₁H₃₁N₃O₅)

b) amlodopine besylate (C₂₆H₃₁N₂O₈SCl) [Note: last element is chlorine)

and

c) hydrochlorothiazide (C₇H₈N₃O₄S₂Cl) [Note: last element is chlorine)

1.  Show your calculation of the molar mass for each of the 3 compounds listed. Again just submitting the molar mass value WILL NOT EARN full credit -- ALL OF YOUR WORK MUST BE SHOWN!  Units count, too!

2.  Show your work as you calculate the % O (oxygen) present in each compound. Again giving only the final answers WILL NOT result in earning full credit for the question.

3.  Rank the 3 compounds in order of INCREASING % O (oxygen).

The order for your answer should be: _____________ (smallest), ___________ , _________________ (largest)

Answer 1

1. Molar mass lisinopril (C21H31N3O5) is calculated as follows

Molar Mass = 12g*21 + 1g*31 + 3*14g + 5*16g = 405 g (mass of H =1g , C=12g , N=14g , O=16 g )

amlodopine besylate (C26H31N2O8SCl)

Molar Mass = 12g*26 + 1g*31 + 2*14g + 8*16g + 1*32 + 1*35.5g = 567.5 g

hydrochlorothiazide (C7H8N3O4S2Cl)

Molar Mass = 12g*7 + 1g*8 + 3*14g + 4*16g + 2*32 + 1*35.g = 297.5 g

2. percentage oxygen

lisinopril = mass of O/Total mass = 80/405 = 19.75%

amlodopine besylate = 128/567.5 = 22.55%

hydrochlorothiazide = 64/297.5 = 21.5%

3. ranking of compound in icreaseing order of % O is

lisinopril < hydrochlorothiazide < amlodopine besylate