The 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? a) 2.2 * 10-34b) 1.3 * 10-10c) 7.8 * 1013d) 4.6 * 1033

There are 7.8 x 10¹³ molecules ghrelin in 1 l blood

Explanation:

Molarity (M) means the number of moles of a solute in one-liter solution. Then, 1.3 x 10⁻¹⁰ M means that there are 1.3 x 10⁻¹⁰ moles of ghrelin in 1 l of blood.

Since 1 mol of something are 6.022 x 10²³ something, then:

1.3 x 10⁻¹⁰ mol ghrelin * 6.022 x 10²³ molecules ghrelin / 1 mol ghrelin

= 7.8 x 10¹³ molecules ghrelin