How Does Solubility Influence Diffusion Rates?

[sameeralord]

Hello everyone,

I got some questions about diffusion. My note says that diffusion is affected by

1. Solubilty of solute- What do they mean by this. Does solubility increase or decrease the rate. Since water is the major liquid found inside the body. Are they referring to solubilty in water. If they are not soluble (non polar) can't they easily diffuse through the membrane. Or are they simply saying that less solubilty means less movement and less diffusion.
2. Concentration gradient- Atleast I understand this.
3. Number of H bonds to be broken- When dissolved in water do they have to break H bonds first before diffusing. I don't understand this.
4. Charge density of electrolytes- I understand why polar molecules would find it difficult to diffuse but not ions. Why would have an ionic charge make it difficult to diffuse?

I also have a question about osmosis and diffusion of ions. When water diffuses through the membrane, does the ions or anything dissolved in it diffuse as well. If so why do ions need specific protein channels for diffusion can't they just diffuse with water.

Thank you very much

 

[Greg Bernhardt]

Hello! It's great that you have some questions about diffusion.

1. Solubility of solute- Solubility is a measure of how much of a solute can be dissolved in a solvent. In the case of diffusion, the solubility of the solute affects the rate of diffusion. For example, if the solute is more soluble, then it will diffuse faster than if it is less soluble. When referring to water, yes, they are referring to solubility in water. Non-polar molecules can still diffuse through the membrane, but their diffusion rate will be slower than polar molecules since they are not affected by the electric field of the cell membrane.

2. Concentration gradient- The concentration gradient is the difference in concentration of the solute from one side of the membrane to the other side. This difference in concentration causes the solute to move from the area of higher concentration to the area of lower concentration, which is known as diffusion.

3. Number of H bonds to be broken- H-bonds are hydrogen bonds that form between two molecules. These bonds must be broken in order for the molecules to diffuse through the membrane.

4. Charge density of electrolytes- Electrolytes carry an electrical charge, which makes them more difficult to diffuse through the membrane. Since the cell membrane has a negative charge, the positively charged ions are repelled and cannot move through the membrane.

When water diffuses through the membrane, it carries the dissolved ions along with it. However, the ions need specific proteins in the membrane called ion channels to facilitate their diffusion across the membrane. These ion channels allow the ions to move through the membrane without having to break any hydrogen bonds.

I hope this helps!