7 - Unit 1, Section 5 - Day 1

Diffusion and Osmosis

Unit 1, Section 5

• Add your salt to the water

• As you swirl the cup, answer the question with your partner:

  • What is being dissolved, and what is it dissolving into?

Salt and Water

Solution - a mixture in which a solid is dissolved in a liquid

• Solute - the solid that is dissolved

• Solvent - the liquid in which the solute dissolves

• Concentration - the amount of solute that is dissolved in a specific amount of the solvent

Solutions

Multiple Choice

In salt water, the salt is the __________.

• Solute.

• Solvent.

• Concentration.

Multiple Choice

In salt water, the water is the __________.

• Solute.

• Solvent.

• Concentration.

• Add a few drops of food coloring to the water without disturbing the water

• Watch how the food coloring spreads throughout the water for one minute

Food coloring and water

Open Ended

Describe how the food coloring spread throughout the water, and how you know it had stopped spreading.

When a solute is first added to a solvent, the concentration is highest where the solute was added

• This creates a concentration gradient between an area of high concentration and an area of low concentration

Concentration Gradients

• Diffusion - the movement of solute molecules from an area of high concentration to an area of low concentration

Diffusion

Open Ended

What do you think happens to the size of the concentration gradient as the solute diffuses through the solvent?

• As the solute dissolves through the solvent, the concentration gradient gets smaller

• Diffusion ends when the concentration gradient is eliminated

When Does Diffusion Stop?