Diffusion & Osmosis Lab A&P

In which temperature (hot/cold) of water did the dye diffuse most rapidly? Explain why this occurred.

In hot water the dye diffused the most rapidly. The water molecules are moving much faster in the hot water than in the cold water. This caused the food coloring the spread.

Homogeneous mixture

Is one made up of materials that are evenly distributed throughout the mixture

Brownian motion

Is the random motion of molecules that occurs as a result of their absorption of heat

Which of two dyes has a smaller molecular size? Why did you reach this conclusion?

Orange has a smaller molecular size because its water changed color, where as green's didn't. This indicated it molecules were small enough to penetrate the dialysis tubing.

Why did we keep the temperature constant (both hot or cold) when we used different shaped containers?

So that water molecules are moving at the same rate.

What do you predict would happen to the bag after several hours?

The bag would burst.

Solvent

The liquid a solute dissolves in. EX: water

solute

The molecule that dissolves; ex: sugar

Detailed information about the Potato & In NaCl and the Distilled water

The potato placed in NaCl made the water leave being (hypertonic). Due to the concentration of solute being higher outside. Water left. The potato placed in distilled water made the potato gain little weight due to just being in water. (This is hypotonic since the potato most likely had more solutes rather than the distilled water.)

Concentration Gradient

The process of particles moving through a solution from an area of higher # of particles to lower. Areas are typically separated by a membrane.

Tonicity

The property of a solution that depends on the osmotic force exerted across a membrane as influenced by the differing concentrations of solutes in and out of a cell.

The reason behind plasmolysis

The water moved to the more concentrated solution (the salt water) so water leaves the cell. The plasma membrane pulls way from the cell wall as the cell shrinks.

Potato is Distilled Water

This was observed as more firm

The potato in the 10% NaCl

This was observed as softer

Did the rate of gain appear to be constant in Activity 3: Using an Artificial Cell to Demonstrate Osmosis.

Yes, the rate of gain did appear to be constant.

semipermeable membrane

a certain size molecule can only pass through EX: a coffee maker

hypertonic solution

a condition in which the environment has a higher solute concentration than inside the cell (concentration of water is greater inside the cell). Osmosis causes water to flow out of the cell and cause the cell to shrink.

hypotonic solution

a condition in which the inside of a cell has a higher concentration than its environment (contraption of water is greater inside the cell). Osmosis causes a net flow of water into the cell, causing swelling and expansion. This swelling may cause cells without a rigid cell wall to burst.

osmotic pressure

concentration of dissolved particles. Also known as the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis

Diffusion

moving from an area of high concentration to an area of low concentration

osmosis

type of diffusion in which water molecules diffuse down a concentration gradient across a semipermeable membrane

Plasmolysis

A condition where a plasma membrane pulls away from the cell wall as the cell shrinks.

Explain why the diffusion rates differed in the different types of containers (hint: Brownian movement should appear in your answer!)

Brownian movement spreads the dye quicker in the narrow tube because the molecules are closer than in the wide.