Problem: Neurotransmitters are molecules that are released by nerve cells to other cells in our bodies, and are needed for muscle motion, thinking, feeling, and memory. Dopamine is a common neurotransmitter in the human brain.Experiments with rats show that if rats are dosed with 3.0 mg/kg of cocaine (that is, 3.0 mg cocaine per kg of animal mass), the concentration of dopamine in their brains increases by 0.75 M after 60 seconds. Calculate how many molecules of dopamine would be produced in a rat (average brain volume 5.00 mm3) after 60 seconds of a 3.0 mg/kg dose of cocaine.

FREE Expert Solution

We have to calculate the number of molecules of dopamine produced in a rat brain when the concentration of dopamine increases by 0.75 M.


We can use the molarity and given volume of rat brain to calculate the number of moles of dopamine. Then we can use the Avogadro’s number to calculate the number of dopamine molecules.


The formula for molarity is:

Molarity = moles of soluteliters of solution


The formula for number of molecules is:

Number of molecules = moles×NA

NA = Avogadro's number = 6.022×1023 particles/mol

View Complete Written Solution
Problem Details

Neurotransmitters are molecules that are released by nerve cells to other cells in our bodies, and are needed for muscle motion, thinking, feeling, and memory. Dopamine is a common neurotransmitter in the human brain.

The structure of benzene is a six-carbon hexagon arranged with its points up and down.  The sides of the hexagon are alternating double and single bonds, with the left side being the first double bond.  The top and bottom point and lower right vertex are all single bonded to H.  The upper and lower left vertices are single bonded to OH.  The upper right vertex is single bonded to C, which is single bonded above and below to H and right to C.  That C is single bonded above and below to H and right to N, which is single bonded to two Hs.

Experiments with rats show that if rats are dosed with 3.0 mg/kg of cocaine (that is, 3.0 mg cocaine per kg of animal mass), the concentration of dopamine in their brains increases by 0.75 M after 60 seconds. Calculate how many molecules of dopamine would be produced in a rat (average brain volume 5.00 mm3) after 60 seconds of a 3.0 mg/kg dose of cocaine.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Molarity concept. You can view video lessons to learn Molarity. Or if you need more Molarity practice, you can also practice Molarity practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Bartoszek Loza's class at OSU.