You have a stock solution of epinephrine at a concentration of 1 mg/ml. knowing that the pipette you will use delivers 20 drops/ml, a. calculate the number of drops of the stock solution that must be added to a smooth muscle bath containing 25 ml of locke’s solution so that the final concentration of epinephrine in the muscle bath will be 100 µg/ml, and

Answer : The number of drops pf the stock solution mist be added are, 50 drops.

Explanation :

As we are given that the concentration of stock solution 1 mg/mL and pipette delivers 20 drops/mL. That means,

1 mg of epinephrine = 1 mL = 20 drops

The final volume of Locke's solution = 25 mL

and the final concentration needed =

As, 1 mL of solution contains =

So, 25 mL of solution contains =

Conversion used :

Now we have to determine the number of drops needed.

As, 1 mg of epinephrine contains 20 drops.

So, 2.5 mg of epinephrine contains 2.5 × 20 = 50 drops.

Therefore, the number of drops pf the stock solution mist be added are, 50 drops.

 The density of  Ammonia is 0.648 g/l

Explanation:

Density = Mass/ Volume

Mass of one mole of  Ammonia (NH3) = 17.031g

Volume =?

Using the ideal gas law we can determine the volume.

PV = nRT

P = 0.913 atm, V= ?, n = 1, R = 0.08206 L.atm/K, and T= 293K

Make V the subject of the formular, we then have;

V= nRT/ P = 1 mol x 0.08206 L.atm/ K.mol x 293 / 0.913 atm

               V = 24.04358/ 0.913 = 26.3L

Having gotten the value of Volume in this question, we then go back to solve for density.

Density = Mass/ Volume

                17.031g/ 26.3L = 0.64756 ≈ 0.648 g/l