Chemistry/ physics?

Question

Vitamin B3 also known as niacin helps maintain the normal function of the skin, nerves and digestive system. The disease pellagra results from a severe niacin deficiency. Niacin has the following formula: C6H5O2. Often tablets contain vitamin B3 in the form of niacinamide C6H6N2O which is easier to absorb. A vitamin tablet contains 100mg of niacinamide
a) What mass of niacin contains an equivalent # of moles as 100mg of niacinamide?

Answer 1

You made a slight mistake in the niacin formula. It is actually C6H5NO2. The molar mass is calculated by adding up all the atomic masses in the formula.
C = 12 x 6 = 72
H = 1 x 5 = 5
N = 14
O = 16 x 2 = 32
So the molar mass of C6H5NO2 is 123 g/mol

The molar mass of niacinamide, C6H6N2O, is 122 g/mol

Whoa! These molar masses are SO similar, that your answer will be VERY close to 100 mg.

100 mg is equal to 0.1 gram. Now convert grams to moles as follows:

0.1 g C6H6N2O x (1 mol / 122 g) = 8.20 x 10^-4 mol

Now convert moles to grams as follows:

8.20 x 10^-4 mol x (123 g/mol) = 0.101 g = 101 mg

Answer 2

C'mon, John.

I'm making a leap of faith that your formulae are correct.

Do the math.

Atomic mass of Carbon = 12
Atomic mass of Oxygen = 16
Atomic mass of Nitrogen = 14
Atomic mass of Hydrogen = 1

(6*12) + (5*1) + (2*16) = 109 for Niacin

(6*12) + (6*1) + (2*14) + (1*16) = 122 for Niacinamide

100 milligms Niacinamide* (gm/1000milligms)*(gm-mole Niacinamide/122 gms) = 8.197x 10^(-4) gm-mole.


8.197x 10^(-4) gm-mole * (109 gm Niacin/gm-mole) = 0.08934 gms Niacin or 89.34 milligms Niacin.

Answer 3

Calculate the molar masses of niacin and niacinamide from their formulas.

100 mg = 0.1 g

Divide 0.1 g by the molar mass of niacinamide to get the number of moles present.

Multiply that by the molar mass of niacin to get the mass of that same number of moles.