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5

Osmotic pressure for non-electrolytic solutes is given by $$\pi = CRT$$ where $C$ is the effective concentration of all the solutes. In our case, with multiple solutes, we simply add all their concentrations to obtain the effective concentration. This gives us $$ \begin{align} \pi_\mathrm{cell} &= 0.05RT\\ \pi_\mathrm{environment} &= 0.03RT \end{...


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Good question, the surprising thing is that you cannot predict conductivity easily. Ammonium acetate, which is a salt of weak acid and weak base, is a comparable conductor as a salt formed by strong acid and strong base (e.g. NaCl). This is a really old table but look at the cases of a) Sodium chloride: salt of strong acid and strong base b) Sodium acetate: ...


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When a weak acid such as acetic acid is added to pure water, it does not ionize much, but sufficiently to make the solution acidic. On the other hand, when small amounts of weak acids are added to buffered solution with a pH near neutral, acidic acid dissociates almost quantitatively. So the van't Hoff factor depends on the pH. The same goes for weak bases ...


4

I couldn't resist. The osmotic pressure equation is $$Π = cRT,$$ where $Π$ is osmotic pressure in atmospheres, $c$ is molar concentration, $R = \pu{0.082057366080960 L atm mol-1 K-1}$ (exactly) and $T$ is temperature in Kelvin. In this problem, $Π = \pu{0.236 torr}$ times exactly $\pu{1 atm}/\pu{760 torr}$ and $T = \pu{(273.15 + 19.0) K}.$ So $c = \pu{1....


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Ultrafiltration is ongoing at any pressure, even if slowly and liquid always goes to the side with lower pressure. Reverse osmosis is ongoing only at pressure higher then osmotic pressure. At pressure lower than osmotic pressure, normal osmosis occurs and liquid flows to the side of higher pressure.


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Let's begin by finding the molarity of each solute in that solution. We'll get to osmolarity later. NaCl The concentration of NaCl given in the problem is $0.04 \frac{\text{g}}{\text{mL}}=40 \frac{\text{g}}{\text{L}}$. We can divide by the molar mass, getting $\frac{40\text{g}}{\text{L}}\cdot\frac{\text{mol}}{58.44\text{g}}\approx0.6845\text{ M.}$ (M ...


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If you want to remove all the moisture content from a small sample on the order of a few mL I suggest using a lyophilizer. It should leave the solutes found in milk largely chemically unaltered. The high sugar and low water content should also serve to preserve the dry product (similarly to powdered milk). The dry product can be resuspended as needed by ...


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Osmotic flow is the movement of a substance (typically water), across a semi-permeable membrane, from the side on which the chemical potential of the substance (water) is higher to the side on which it is lower. I.e., just as temperature provides a gradient for the flow of thermal energy, chemical potential provides a gradient for the flow of matter. Thus ...


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