Catalyst
1. Describe how dispersion forces are created2. What intermolecular forces does HF contain?3. What intermolecular forces does NCl3
contain?
End
Today’s Learning Targets• LT 4.1 – I can discuss how ionic solids dissolve due to the
random molecular motion of the water molecules. • LT 4.3 – I can compare and contrast various intermolecular
forces and relate them to the dissolving process of a solid. • LT 4.4 – I can hypothesize how surface area, temperature,
and pressure impact the dissolving process of a solid.
I. The Dissolving Process• The dissolving process is facilitated by motion of
liquid molecules and intermolecular forces.• Liquid molecules are moving in random motion.• When a molecule is dissolved in water, water
molecules hydrogen bond with one another to form a cage to dissolve.
II. Like Dissolves Like
• Like substances dissolve like substances • If something has a charge, then it will not be
able to dissolve something that does not have a charge.
Sugar Cube Investigation• We can make statements
about what we think is the answer to a question, but a good scientist experiments
• You are going to be doing an investigation with your group to determine how surface area and temperature impact the rate at which something dissolves.
Lab Conduct• Follow the procedure that has been given to
you• Respect the equipment. It costs a lot of money
to replace this stuff• Use the chemicals in a responsible and safe
way• Clean up the space when you are done• Read the steps, they will tell you what to do.
Lab Debrief• What happens to the rate at which the sugar
dissolved as you increased the temperature?• What happens to the rate at which the sugar
dissolved as you increased the surface area?• Why?!?!?!
Justify – TPS• Why does this solid appear at cold
temperatures, but it wasnt present when the cider was hot?
I. Dissolving• We can alter the rate at which the solute
dissolves by:1. Changing the temperature2. Changing the surface area of the
solute3. Changing the pressure of the solution.
II. Temperature and Dissolving• As you increase the
temperature, molecules start moving faster.
• By moving faster, the molecules are better able to grab the solute, form the cages around them and pull them into the solution.
• Therefore, the faster molecules are moving, the faster something dissolves.
III. Surface Area and Dissolving
• As you increase the surface area, the rate at which the solute dissolves increases.
• As you increase the surface area of a substance, you are providing more sites for the solvent to interact with the solute.
IV. Pressure and Dissolving• As you increase the pressure, the rate at
which the solute dissolves increases.• The solubility and pressure relationship is
clearly seen when a gas dissolves in a liquid. • Gases can dissolve into liquids.
IV. Pressure and Dissolving• When a gas is above a liquid and the pressure
is increased, the gas molecules collide more often with the wall of the liquid and this causes more gas to be pushed into the liquid.
Mind Maps• We will be making mind maps
to understand the connections between concentration calculations and solution chemistry
• In the center of our mind map will be the term “Solution Chemistry”
• You will have branches coming up for all the terms that you think are important for the idea of solution chemistry
Mind Map Work Time• Your mind map must contain the following words/terms/Ideas:
– Molarity - Hydrogen Bonding– Percent Composition - Dipole-Dipole Forces– Crystal Lattice - Dispersion Forces– Intermolecular Forces - How atoms are – Solvent arranged in solids/– Solute liquids/gases– How dissolving occurs -How pressure, volume at the
molecular level and temperature influence dissolving
• Put as many things as you know! USE NOTES!• Use colors!