Calculate the rate of dissolution (dm/dt) of relatively hydrophobic drug particles with a surface area of 2.5×103 cm2 and saturation solubility of 0.35 mg/ml at 25°c in water. the diffusion coefficient is 1.75×10-7 cm2/s, and the thickness of the diffusion layer is 1.25m. the concentration of the drug in the bulk solution is 2.1×10-4 mg/ml.

Explanation:

We can use the Noyes-Whitney equation to calculate the rate of dissolution.

Data:

D = 1.75 × 10⁻⁷ cm²s⁻¹

A = 2.5 × 10³ cm²

Cₛ = 0.35 mg/mL

C = 2.1 × 10⁻⁴ mg/mL

d = 1.25 µm

Calculations:

Cₛ - C = (0.35 - 2.1 × 10⁻⁴) mg·cm⁻³ = 0.350 mg·cm⁻³

d = 1.25 µm = 1.25 × 10⁻⁶ m = 1.25 × 10⁻⁴ cm

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )