Question

1/ What is the formula weight for iron (III) oxide, in amu ?

2/ what is the atomic mass for capsaicin ( C18H27NO3) which is responsible for the heat of a chili pepper, in amu ?

Answer 1

1) Iron (III) oxide is Fe2O3   , O has 15.999 amu , Fe has atomic mass of 55.845 amu

Fe2O3 molar mass = ( 2 x Fe atomic mass) + ( 3 x O atomic mass)

= ( 2 x 55.845 amu) + ( 3 x 15.999 amu)

= 159.7 amu

2) C18H27NO3 molar mass = ( 18 x C atomic mass) + ( 27 x H atomic mass) + N atomic mass +

                                          (3 xO atomic mass)

             = ( 18 x 12.01 amu) + ( 27 x 1.008 amu) + ( 14 amu) + ( 3 x 15.999 amu)

        = 305.4 amu