# The concentration of the appetite-regulating hormone 1.3 times 10^-10 M in a fasting person. How many molecules of ghrelin are in 1 L of blood?

##### 1 Answer
Sep 4, 2017

Approximately $7.8 \cdot {10}^{13}$ ghrelin molecules are present in a fasting person's blood.

#### Explanation:

$M$ is molarity, units of molarity are $\frac{m o {l}_{s o l u t e}}{{L}_{s o l n}}$.

Thus there are $1.3 \cdot {10}^{-} 10 m o l$ per liter of blood.

Furthermore, using Avogadro's number, we'll arrive at the solution:

1.3*10^-10mol* (6.023*10^23 " molecules")/(mol) approx 7.8*10^13" molecules"

Ghrelin is a protein that functions as a hormone: