What substance was diffusing into the agar cubes?

What substance was diffusing into the agar cubes?

We know the sodium hydroxide diffuses into the agar cube because the cube turned purple as it entered the cube containing the phenolphthalein, an indicator of base.

How can you determine the rate of diffusion in the agar cubes?

Calculating % diffusion in each cube:

1. Calculate total volume of each cube (volume = L x W x H)
2. Calculate volume that did not turn pink.
3. Calculate volume diffused = total volume – volume not pink.
4. Calculate % diffusion = Volume diffused /total volume x 100.

What do the agar cubes represent in this lab?

The agar cubes represent biological cells. The volume of the cube correlates to the cytoplasm and the surface area of each cube to the cell membrane. All living cells are dependent on diffusion processes for survival. These processes transport materials across the cell membrane into and out of the cell.

How can agar be used to represent diffusion?

Use cubes of agar to investigate how size impacts diffusion. All biological cells require the transport of materials across the plasma membrane into and out of the cell. By infusing cubes of agar with a pH indicator, and then soaking the treated cubes in vinegar, you can model how diffusion occurs in cells.

What is diffusion extent?

Extent of the concentration gradient: The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of the material gets to equilibrium, the slower the rate of diffusion becomes.

Why does diffusion occur?

Diffusion happens because gases and liquids move from place to place in quick random motions. When this happens, the particles collide, which in turn makes them change directions. The process of diffusion occurs on its own without any help from shaking or stirring.

What percentage of each cube’s volume was reached by diffusion?

Note that 100% of the smallest cube’s volume has been reached by the vinegar, while only 19% of the largest video is reached by diffusion. The basic idea: small size results in a high surface area to volume ratio, which enhances diffusion. And that’s why cells are small.

What is the relationship between SA v ratio and diffusion time?

Explanation: When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared. When there is more volume and less surface area, diffusion takes longer and is less effective.

How is distance measured in diffusion?

D is the diffusion coefficient of a solute in free solution. The diffusion coefficient determines the time it takes a solute to diffuse a given distance in a medium. D has the units of area/time (typically cm2/s)….

What are agar cubes made of?

Agar consists of a mixture of two polysaccharides: agarose and agaropectin, with agarose making up about 70% of the mixture. Agarose is a linear polymer, made up of repeating units of agarobiose, a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose.

What is diffusion rate?

The rate of diffusion, dn/dt, is the change in the number of diffusing molecules inside the cell over time. Since the net movement of diffusing molecules depends on the concentration gradient, the rate of diffusion is directly proportional to the concentration gradient (dC/dx) across the membrane.