How does diffusion differ from osmosis

To answer the question, you need to know the definitions of osmosis and diffusion and really understand what they mean. Osmosis and diffusion are related processes that display similarities:. Here's how they are different:. Facts to remember about diffusion and osmosis:. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance.

Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Table of Contents Expand. Key Points. Anne Marie Helmenstine, Ph. The flow of constituents is in all directions. The flow of constituents occurs in one direction only.

Diffusion is a natural phenomenon that can not be stopped. The process can be stopped or we can reverse it by applying an external force. All the types of substances present in the solution can move from the region of its high concentration to the region of low concentration.

For instance, when placed in water, red blood cells will let the water creep through their membrane. When placed in a concentrated solution of sugar, the red blood cell actually shrinks because the water moves out by osmosis towards the area of lower water concentration.

This is why the cells appear wrinkled when viewed through a microscope. Luckily, this never happens inside the body because the kidneys make sure the concentration of the blood stays about the same as the concentration of the solution inside the red blood cell.

Unlike red blood cells, plant cells have a far stronger and more rigid cell wall on the outside of the cell membrane.

This enables the plant cells to absorb more water by osmosis without bursting. If plant cells lose too much water by osmosis , they become less rigid , and eventually , the cell membrane shrinks away from the cell wall. When osmosis is used to equalize concentrations on both sides of the membrane, it exerts a force called osmotic pressure.

For instance, picture two compartments in a tank separated by a semipermeable membrane that only allows water molecules to pass through.

One compartment is filled with a salt solution , while the other adjacent compartment is a pure water solution.

The only way equilibrium can be reached is by transporting water from the pure water compartment to the saltwater compartment. In doing so, osmosis r a ises the level of liquid in the saltwater compartment until enough pressure caused by the difference in levels between the two compartments stops the processes.

The pressure it takes to reach this equilibrium is called the osmotic pressure. In other words, instead of seeking an equal balance of solvent and solute in both solutions, reverse osmosis separates the solute from the solvent.

Reverse osmosis is very handy for applications like water desalination removing salt from seawater. Worldwide, there are now over 13, desalination plants in the world. In reverse osmosis, we are literally just reversing the proces s b y making our solvent filter out of our high concentrate and into the lower concentrate solution , s o instead of creating an equal balance of solvent and solute in both solutions, it is separating out solute from the solvent. Tibi is a science journalist and co-founder of ZME Science.