Question

Epinephrine (adrenaline) is a hormone secreted into the bloodstream in times of stress. It contains 59.0% C, 7.15% H, 26.20% O, and 7.65% N and has a molar mass of 183 g/mol. What is its molecular formula

Answer 1

C9H13O3N

Step-by-step explanation:

Take the atomic mass of C=12.0, H=1.0, O=16.0 and N=14.0.

We can draw a chart (please view this on desktop so to avoid spacing errors):

Let the mass of Epinephrine be 100g.

C H O N

mass(g) : 59 7.15 26.2 7.65

no. of moles : 59/12 =4.9167 7.15/1 = 7.15 26.2/16=1.6375 7.65/14=0.5464

(n.o.m. = mass/molar mass)

Ratio: 4.9167/0.5464 =9 7.15/0.5464=13 1.6375= 3 0.5464/0.5464 =1

(divide the n.o.m. by the smallest n.o.m., which is 0.5464 in this case, take the whole numbers)

So, the empirical formula will be: C9H13O3N

But this is still not yet the molecular formula. We have to ensure the molar mass is 183g/mol. Multiply the empirical formula by n.

So, let the molecular formula of Epinephrine be (C9H13O3N)n.

12x9n + 1x13n + 16x3n + 14n = 183

108n + 13n + 48n + 14n = 183

183 n = 183.

n = 1

Hence, the molecular formula is C9H13O3N.