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Solutions & Solubility. Day 2. Solubility Rules. Use STAAR chart to determine whether or not a compound is soluble (aq) or insoluble (s) Cu(NO 3 ) 2 MgCO 3 NH 4 Cl NaOH Mg(OH) 2 PbCrO 4. Solubility and Factors affecting solubility.
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Solutions & Solubility Day 2
Solubility Rules Use STAAR chart to determine whether or not a compound is soluble (aq) or insoluble (s) Cu(NO3)2 MgCO3 NH4Cl NaOH Mg(OH)2 PbCrO4
Solubility and Factors affecting solubility Solubility- the amount of a substance required to form a saturated solution with a specific amount of solvent at a specific temp. • ex: the solubility of sugar in water is 204 g/100 ml of water at 20oC.
Factors affecting the RATE OF DISSOLUTION (how fast is dissolves): • 1) STIR (agitate)- Brings “fresh” solvent into contact with the solute increasing collisions between particles
2) HEAT - Increases the kinetic energy (particles start moving faster) of the solvent molecules causing more frequent collisions between the solvent and solute
3) Crush/Grind It reduces the particle size and increases the surface area of the solute exposed to the solvent causing more frequent collisions between particles
Factors affecting solubility(how MUCH dissolves) Solubility- the amount of a substance required to form a saturated solution with a specific amount of solvent at a specific temp. • ex: the solubility of sugar in water is 204 g/100 ml of water at 20oC.
1) Polarity “Like dissolves like”- solubility of a substance is related to the nature of the solvent.
The Solution Process “like dissolves like”- like refers to the polarity of the solute and solvent • Polar solvents will dissolve POLAR & IONIC solutes water will dissolve salt water will dissolve sugar • Nonpolar solvents will dissolve NONPOLAR solutes gasoline will dissolve oil
The Solution Process miscible (soluble)- dissolves in all proportions ethanol is miscible in water because they are both polar
The Solution Process Immiscible (not soluble)- vegetable oil is immiscible in water.
The Solution Process oil will not dissolve in water because oil is nonpolar and water is polar
2) TEMPERATURE • Increased temp of solids solubility • Increased temp of gases solubility GASES SOLIDS
Factors affecting solubility • PRESSURE • only affects the solubility of gases. pressure, increased solubility (soda) pressure, decreased solubility(fizz) • Solubility of liquids and solids is not changed by changes in pressure.
Activity 1: • Place a Styrofoam cup in Beaker A. What happens? • If beaker A contains water, what can you tell me about the substance Styrofoam? • Now place the cup in Beaker B. What happens? • Without me telling you what the liquid in Beaker B is, what do you already know about it? • Draw and label a picture of this at the bottom of your notes.
FYI… Henry’s Law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid. When a soda fizzes and rapidly releases gas its called effervescence.
Day 2 Activity : • Make a small oval shaped pile of shaving cream directly on your table. Spread out with your wood stick. • Select 2-3 colors of food coloring and drop 5-6 drops in different locations on the pile. • Using a coffee stirrer, MARBLE (don’t whip!) the food coloring through the shaving cream making a swirl pattern.
Cellulose (in paper) • Write your name decoratively on an index card with Sharpie. • Dip the card into the shaving cream (name side down). • Use a ruler to scrape off the shaving cream.