Solutions

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Agenda Solutions Notes Solubility Curve Practice SAT Science Reading

Talk in your group What is a solution? What are some examples?

What is a Solution? A Homogeneous mixture of a solute dissolved in a solvent Everytime you look, you get the same thing – salt water, Gatorade, etc.

Examples of a Solution Salt or sugar water Gatorade Pop (soda) Everytime you look you get the same thing

What is a Solution? Solute: component(s) present in a smaller amount Solvent: component present in the greatest amount Assume that it is water, unless stated otherwise Solvents and solutes can be solids, liquids, or gases EX: CO2 in pop EX: acetic acid to make household vinegar compounds **Does not have to be a solid Substances that dissolve most readily in water are ionic compounds and polar covalent molecules. As individual solute ions break away from the crystal, the negatively and positively charged ions become surrounded by solvent molecules and the ionic crystal dissolves = solvation. In some ionic compounds, the attractions among the ions in the crystals are stronger than the attractions exerted by water. These compoudns cannot be solvated to any significant extent and are nearly insoluble. Barium sulfate and calcium carbonate

Can a solute only be a solid? Talk about it Can a solute only be a solid?

NOPE! Can be a solid, liquid, or gas!! **CO2 in pop (soda) **acetic acid to make household vinegar compounds

Checkpoint 1: A solution is a: Heterogeneous mixture of solute dissolved in solvent Heterogeneous mixture of solvent dissolved in solute Homogeneous mixture of solute dissolved in solvent Homogeneous mixture of solvent dissolved in solute C

Checkpoint 2: Which combination is correct? Kool-aid is in the powder, solid form. Solute Solvent A Water Kool-Aid B Salt C D Remember: If not stated, then water is the solvent C

Electrolytes A compound that conducts an electric current when in an aqueous solution or in the molten state Ions must be mobile, “free,” to carry an electrical current All ionic compounds

What is the Solution Process? As individual solute ions break away from the crystal, the negatively and positively charged ions become surrounded by solvent molecules and the ionic crystal dissolves = solvation. In some ionic compounds, the attractions among the ions in the crystals are stronger than the attractions exerted by water causing them to be insoluble. Barium sulfate and calcium carbonate Barium sulfate and calcium carbonate insoluble

What is Solubility? The maximum amount of solute dissolved in a solvent at a specific temperature

There are 3 Types of Solutions:

What are types of Solubility? Unsaturated Contains less than the maximum amount of solute that a solvent can hold at a specific temperature Like adding a half of a packet of kool aid to water

What are types of Solubility? Saturated Contains the maximum amount of solute that a solvent can hold at a specific temperature Full packet of kool aid

What are types of Solubility? Supersaturated Contains more than the maximum amount of solute that a solvent can hold at a specific temperature

https://www.youtube.com/watch?v=FcxZ9DyOaUk

What effects Solubility? Temperature Surface Area Stirring Pressure (gas) Amount solvent Surface area – crush it up, able to dissolve faster Butter and bread analogy Stirring – increase the motion and then increase the interaction of molecules Add more solvent if you have a supersaturated solution Increase pressure to squeeze molecules closer together in order to have more collisions

Checkpoint 3 Which of the following increases the solubility of a solute in a solvent? Decrease the amount of solvent Increase the amount of solute Increase the temperature Decrease the surface area C Not B because you want to increase the amount of SOLVENT not SOLUTE

Checkpoint 4 Crushing a cube of sugar into small granules: Increase the surface area and increase solubility Increases the surface area and decreases solubility Decreases the surface area and increases solubility Decreases the surface area and decreases solubility

Solubility Curves Used to make a saturated solution in the lab Tells us what mass of solute will dissolve in 100g of water over a range of temperatures So how do we know how to make a saturated solution in the lab? We can use solubility curves which tells us what mass of solute will dissolve in 100 g or 100 mL of water over a range of temperatures.

Solubility Curves Find the curve for KClO3 At 30°C approximately 10g of KClO3 will dissolve in 100g of water. If the temperature is increased to 80°C, approximately 40g of the substance will dissolve in 100g (or 100mL) of water. @30C

Checkpoint 5 What mass of KNO3 will dissolve in 100mL of water at 70°C? 0 g 43 g 100 g 140 g

Checkpoint 6 What mass of NaCl will dissolve in 100mL of water at 100oC? A. 0 g B. 40 g C. 100 g D. 130 g B

Solubility Curves Values on the curve represent saturated solutions Values on the graph below a curve represent unsaturated solutions Values above a curve represent supersaturated solutions All info on the solubility curve is for saturated solutions

Checkpoint 7 What term best describes a solution that contains 70g of NaNO3 per 100mL water at 30°C? Saturated Supersaturated Unsaturated

Checkpoint 8 What term best describes a solution that contains 60g of dissolved KCl per 100mL water at 80oC? A. Saturated B. Supersaturated C. Unsaturated

Concentration The amount of a substance in a given unit of volume Mass of solute per volume of solution 10 g NaCl in 100 mL water = 10/100 = 0.1g/mL Percent by mass 10 g NaCl in 100 mL water = 10% NaCl solution Molarity - Moles of solute dissolved in 1 L of solution 10. g NaCl in 100. mL water = 0.17 moles NaCl / 0.100 L = 1.7 M

Concentration Concentrated solution – contains a large amount of solute Dilute solution – contains a small amount of solute

Suspensions & Colloids Heterogeneous mixture Particles are much larger and do not stay suspended indefinitely Colloid Contains particles intermediate in size between those in a solution and those in a suspension Whipped cream, marshmallow, geletin, milk, mayonnaise, fog, aerosols, dust in air, egg white, jellies, paint, blood Emulsion – colloid dispersion of a liquid in a liquid