1. Dissociation & Rate of Dissolving
Bundle 4: WateR, Solubility, and ph

2. Watch the following video and write down your observations
engage
Watch the following video and write down your observations

3. QUICK WRITE – 2 Minutes What did you see happen in the video?
Now, turn to your table partner and together discuss what happened and draw it on the paper provided.
Be prepared to share with the class.

4. Table Talk – 1 minute Question:
Why do the water molecules orient themselves differently around the anions and cations in salt?
Answer: electrical attraction Because Water is polar! The Water Molecule has charged ends so the positive end of a water molecule is attracted to the negative chlorine ion, and the negative end of a water molecule is attracted to the Positive sodium ion.

5. Dissociation
Dissociation (Dissolving) is a process where the positive and negative ions of a substance come apart as an ionic compound dissolves in a solvent, like water.
Dissociation is reversible because the original ionic compound does not change, therefore dissociation is a physical change
ONLY Ionic compounds dissociate

6. Dissociation of Ionic compounds
Dissociation is a separation of ions that already exist.

7. activity
At your table, create a picture of the dissolving of salt ions in water using the ion and water molecule pictures.
Color the ions and water molecules as instructed below:
Sodium – green
Chlorine – red
Oxygen – blue
Hydrogen – orange
Glue or tape your pictures in your ian notebook showing the correct configuration of water molecules around the salt ions
When finished, your teacher will stamp your picture if it is correct

8. Question
If you wanted to dissolve a substance in water quickly, what are some things you could do to make it happen faster?

9. DEMO
What factors do you think affect how quickly something dissolves?

10. Rate of dissolving
There are 3 factors that affect the rate at which a substance will dissolve in water.
Agitation
Increased surface area
Increased temperature

11. AGitation
Agitating mixture (stir, shake) - moves dissolved solute particles away from contact surfaces more quickly allowing new collisions between solute and solvent.
Ex. Sugar stirred in tea vs. unstirred.

12. Increased Surface Area
a greater Surface Area allows more collisions to occur.
The surface area can be increased by crushing or grinding the solute to change into powder
Ex: sugar cube vs granulated sugar

13. IncreaseD temperature
increases the KINETIC energy (energy of movement) resulting in more frequent collisions with greater energy.
Ex. Sugar dissolves faster in hot tea than in cold tea.

14. Rate of dissolving lab Go to your assigned lab table
Complete the three tasks in 10 minutes or less
Answer the guided questions
Return to your seat and write your summary of the lab
Be prepared to share with the class