Consider an osmometer, a device to measure osmotic pressure generated by a macro
ID: 892950 • Letter: C
Question
Consider an osmometer, a device to measure osmotic pressure generated by a macromolecule that cannot pass a semi-permeable membrane, though water and salts can pass. For simplicity, we will assume that the protein is pure, that is, a single macromolecular component, and that it does not dissociate, and thus a solution corresponds to a definite molecular weight. The working equation is: PI = hydrostatic pressure = rho gh (where rho is the density of the solution, g is gravitational acceleration, and h is the height of the meniscus in the tube above the surface of the solution outside the tube = n_B RT/V, where n_B denotes the number of moles of component "B", the protein, V is the volume that contains the protein (and is thus inside the apparatus connected to the vertical tube), R the molar gas constant, T the absolute temperature. Note that n_B/V = W/M, where W is the weight concentration of the protein (gms/L) in the protein solution within the apparatus. Be sure your equations have the correct units (M, Kg, secs, etc. pr gm, cm, secs, etc). Report the height of the column in cm. Calculate h for w=0.5, 10, 25, and 50 gm/L and for a protein of MWt = 15,000 gm/mole.Explanation / Answer
Consider an osmometer, a device to measure osmotic pressure generated by a macro