He concentration of the appetite-regulating hormone ghrelin is about 1.3 × 10-10 m in the blood of a fasting person. how many molecules of ghrelin are in 1 l of blood?

To solve this problem, let us first calculate for the number of moles of ghrelin in the blood. This is calculated by using the formula:

number of moles of ghrelin = Molarity * Volume of blood

number of moles of ghrelin = (1.3 × 10^-10 mol / L) * (1 L)

number of moles of ghrelin = 1.3 × 10^-10 mol

Avogadro’s number states that for every mol of a substance there is approximately 6.022 x 10^23 atoms or molecules of that substance. Therefore converting this into number of molecules:

number of molecules of ghrelin = 1.3 × 10^-10 mol (6.022 × 10^23 molecules / mol)

number of molecules of ghrelin = 7.8286 × 10^13 molecules