unit 10- solutions and gases lecture 3: factors affecting...
TRANSCRIPT
Monday, April 13, 2015 WELCOME BACK! Unit 12: Solutions! 12.1 Solubility
WHAT QUESTIONS DO YOU HAVE TO FROM BREAK WORK?
Binder HW for checking: ALL: BREAK WORK Juniors: completed Regents Exam Sophomores: EC
Notes: DO NOW
(Seat)
Chemistry Reference Table
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matter
Pure substance Mixture
Element Compound Homo-
geneous
Hetero-
geneous
Homo-
geneous
Solute
Solvent
This is the greatest thing ever invented. At the end of the lesson, you will tell me why the “solution” to
waterproof mascara is solved by this magical goodness.
Quick Practice
Solution Solute Solvent
NaCl (aq)
C6H12O6 (aq)
AgNO3 (aq)
NaCl Water!
C6H12O6 Water!
Water! AgNO3
Soluble/Insoluble? Dissolves or does not
dissolve? Homogeneous or Heterogeneous?
Soluble
Insoluble
Dissolves Homogeneous
Does not
dissolve Heterogeneous
VIRTUAL STATIONS
• The next two slides will take you through the factors that affect solubility. For each slide I want you to consider what the factor is (ex. Temperature, pressure, etc.) and the trend for solubility.
• THERE WILL BE NO TALKING, CALLING OUT, ETC. in this activity in order to give all students a chance to think about what they see!
VIRTUAL STATION: FACTOR 1
SCENARIO: Dissolving sugar in hot coffee versus iced coffee. Which dissolves more quickly?
VIRTUAL STATION: FACTOR 2
SCENARIO: Both of these bottles contain seltzer water. Which was is the gas less soluble in? THIS IS TRICKY!
VIRTUAL STATIONS DEBRIEF
FACTORS EFFECTS
TEMPERATURE The hotter the solvent, the more soluble the solute is.
PRESSURE FOR GASES ONLY! The higher the pressure, the more soluble the gas is.
Let’s talk exceptions.
FACTORS EFFECTS EXCEPTIONS
TEMPERATURE The hotter the solvent, the more soluble the solute is.
FOR GASES- Gasses are more soluble in colder solutions.
PRESSURE FOR GASES ONLY! The higher the pressure, the more soluble the gas is.
DOES NOT EFFECT SOLIDS OR LIQUIDS.
WHY?!
• When a solute dissolves in solution, it requires interaction between the solvent and the surface of the solute (IT NEEDS TO MIX TOGETHER!)
Question.
HOW IS THE PROCESS OF DISSOLVING DIFFERENT FROM COLLISION THEORY?
POLARITY
What is polarity?
Unequal sharing of electrons due to large difference in electronegativity.
What trends do you see?
Solute Type Nonpolar solvent Polar solvent
Non-polar Soluble Insoluble
Polar Insoluble Soluble
“LIKE DISSOLVES LIKE!”
How does polarity affect solubility?
FACTOR EFFECT EXCEPTIONS
POLARITY “Like dissolves like”
Ionic compounds
Critical Thinking
• Having more surface area makes something dissolve faster. Why is this not considered a factor that affects solubility?
– Powdered sugar vs. sugar cubes—both are the exact same chemical, sucrose, C12H22O11
• However, smaller particles are more likely to dissolve than large particles.
– Sucrose vs. Starch
– C12H22O11 vs. C200H400O200
Quick Practice
Solute Solubility Polar or non-polar
Oxygen (O2) Insoluble
Glucose (C6H12O6) Soluble
Hexane Insoluble
Nitrogen (N2) Insoluble
Does this make sense?
70% Isopropyl Alcohol 30% Water
Canola Oil Water
Why does the bear dissolve in water?
BECAUSE IT’S POLAR!
This knowledge basically solved 99% of the problems in my life.
The quest for the best mascara… calls for the best eye makeup remover.
Why do we care about this?!
Self-experimenting with waxing usually leads to chaos.
Classwork Time!
Closing summary
What four factors affect solubility?
temperature, pressure, and polarity, size of particles!
What increases solubility for liquids and solids?
Small particle size and high temperatures!
What increases solubility for gases?
Low temperatures, high pressure