Agenda • Warm Up • Introduction to Solutions • Demo: Acetone and Foam • Assign Solutions Poster Assignment (Due Monday April 20th) **HW: Work on Poster Warm Up • In your notebook, write 2-3 sentences describing what you think a solution is. Solutions • There are many types of solutions Solutions A solution is a homogeneous mixture. The components are not chemically combined, but just intermingled uniformly. Example: Coffee is the same from the first sip, to the last. Solutions A solution is made up of a solute and solvent. •Solute: a dissolved substance •Solvent: the most abundant component of a solution, i.e what does the dissolving •In a salt water solution, what is the solute and what is the solvent? Solutions • Solvation is the scientific term for the process of dissolving a solute in a solvent. • If a solute dissolves in a solvent, it is said to be soluble. Conversely, if a solute does not dissolve in a solvent it is said to be insoluble. Solutions Water is called the “universal solvent” because it has the ability to dissolve so many substances. Why? Solutions • Remember, water is a polar molecule. • Polar and ionic solutes will dissolve in water because of the interactions of opposite charges. Dissolving Polar Molecules • Polar water molecules surround the polar solute molecules, pulling them away from each other. • All the molecules themselves, remain intact! Dissolving Ionic Compounds • The cations and anions that make up the ionic compound break apart and each is surrounded by polar water molecules. • “Dissociation”: ionic compounds separate into cations and anions. Solutions When something is dissolved in water the resulting solution is said to be an aqueous solution. Agenda • Warm Up • Factors affecting dissolving rate, saturated/supersaturated solutions • Very brief video • Solutions practice ws **HW: Solutions practice ws, continue working on poster due 4/20 Warm Up • In your notebook, write 2-3 sentences fully describing how an ionic compound (such as salt) dissolves in water. Solubility • Solubility describes how well a solute dissolves in a solvent (usually water). • Soluble solutes dissolve readily • ex. Salt in water • Insoluble solutes do not dissolve readily Solubility of Liquids • Miscible: two liquids which uniformly mix together (ex: milk and water) • Immiscible: two liquids which will not mix, forms two layers (ex: oil and water) As a general rule: “Like dissolves like” Non-polar + non-polar = miscible Polar + Polar = miscible Non-polar + Polar = immiscible Solubility of Liquids Solubility Factors • Recall that solubility is how well one substance dissolves in another • Several factors can speed up the dissolving of solid solutes in a solvent • Surface area; Powdered substances dissolve faster than cubed substances • Temperature; solids dissolve faster at higher temperatures than at lower temperatures (**Gases are an exception to this rule**) • Agitation: Stirring causes solids to dissolve faster Describing Solutions Solutions are described as: •Saturated: No more solute can dissolve •Unsaturated: More solute can dissolve •Supersaturated: More solute is dissolved than theoretically possible •These descriptions ultimately depend on the type/amount of solute and amount/temperature of water Describing Solutions • To further describe a solution we must also specify the relative amount of solute and solvent. • Concentration indicates the amount of solute dissolved in a given quantity of solvent. • Dilute: a small amount of solute • Concentrated: a large amount of solute Describing Solutions Describing Solutions •Supersaturated solutions are fun for Chemists; Here’s why! Agenda • Review HW • Saturated vs. Unsaturated POGIL • If you need your NB checked, bring it to me up front. • If you qualify for SG enrichment, let me know **HW: Complete POGIL due tomorrow, continue working on poster due Monday Agenda • POGIL Key will be posted online • Warm Up • Concentration, Molarity and Mass Percent • Molarity Practice ws **HW: Complete Practice ws, Finish poster due Monday Warm Up 1. A solution that has the maximum amount of solute dissolved in it is known as what type of solution: 2. A solution that has the less than the maximum amount of solute dissolved in it is known as what type of solution: 3. A solution that has the more than the maximum amount of solute dissolved in it is known as what type of solution: 4. How could someone increase the rate at which the solute that dissolves? 5. If you have a polar solvent like water, what kind of compound would most likely dissolve in it? Molarity • Recall that concentration of a solution indicates how much solute is dissolved in a given amount of solvent. • Concentration is expressed mathematically as Molarity • Molarity expresses concentration as number of moles of solute per liter of solution (units are mol/L = M) Molarity The formula for Molarity is: Let’s practice! What is the molarity of a solution that contains 1.4 moles of solute in 2L of solution? 0.7 M Molarity • Molarity questions are often not as straightforward as that. • Sometimes you will need to convert mass of solute (g) to moles of solute. Molarity Practice What is the molarity of a solution containing 0.900 g NaCl in 100 mL of solution? 0.900 g NaCl x 1 mol NaCl = 0.0150 mol NaCl 58.44 g NaCl Now we can plug into our molarity formula: 0.0150 mol NaCl = 0.150 M NaCl 0.100 L 100 mL = 0.100 L Molarity Practice What is the molarity of a solution with a volume of 2.00 L containing 36.0 g of C6H12O6 (glucose)? 36.0 g C6H12O6 x 1 mol C6H12O6 = 180.18 g C6H12O6 0.200 mol C6H12O6 Now plug into the molarity formula 0.200 mol C6H12O6 2.00 L = 0.100 M C6H12O6 Molarity Practice How many moles of solute are in 3.80 L of 0.700 M NaClO (bleach)? 3.80 L x 0.700 mol NaClO 1L 0.700 M written as mol/L = 2.66 mol NaClO Molarity Practice How many moles of solute are in 250 mL of 2.20 M CaCl2? 0.250 L x 2.20 mol CaCl2 = 0.550 mol CaCl2 1L 250 mL = 0.250 L Molarity Practice What mass of sodium hydroxide (NaOH) is needed to make 250mL of a 0.150M solution? 0.250 L x 0.150 mol NaOH = 0.0375 mol NaOH 1L 0.0375 mol NaOH x 40.00 g NaOH = 1.50 g NaOH 1 mol Molarity Practice How many liters of a 1.15 M solution are needed to give 0.805 moles of solute? 0.805 mol x 1L = 0.700 L 1.15 mol How many mL are needed? 0.700 L = 700 mL Molarity practice • Molarity can also be expressed as Mass percent • Mass percent = mass of solute X 100 mass of solution Molarity practice How many grams of a solution that is 32.7% by mass NaCl would contain 45.0 g of NaCl? Mass percent = mass of solute mass of solution 32.7 % = 45.0 g mass of solution Mass of solution = 45.0 g 0.327 X 100 X 100 = Divide both sides by 100 and Cross Multiply! 138g Agenda • Please turn in your poster. • Warm Up • Review Molarity HW • Dilution lesson • Dilution Practice ws **HW: Complete dilution practice ws, due next class Constructed Response Gases on 4/28!! Warm Up • How many mL of a 1.63 M solution would contain 12 g of NaOH? • What is the molarity of a solution that is made by adding 57.3 g of MgO to 24.6L of solution? Dilution • Dilution is the process of adding more solvent (always water) to a solution. • By doing so, the concentration (Molarity) of the solution becomes lowered. • It is important to note that the amount of solute does not change. Therefore, the moles of solute is the same before and after the dilution. Dilution 6 mol in 100 mL 6 mol in 200 mL same amount of solute Dilution Dilution • Because the moles of solute are the same before and after the dilution, we can relate this using the mathematical formula: initial Molarity initial Volume Molarity of dilute solution Volume of dilute solution Dilution Practice • How many mL of 2.00 M MgSO4 must be diluted to prepare 100 mL of 0.400 M MgSO4? (2.00 M) x V1 = (0.400 M) x (100 mL) (0.400 M) x (100 mL) = V1 = 20.0 mL (2.00M) Dilution Practice 200 mL of 10.0 M NaOH is diluted to 500 mL, what is the molarity of the dilute solution? (10.0 M) x (200 mL) = M2 x (500 mL) (10.0 M) x (200 mL) = M2 = 4.00 M (500 mL) Agenda • Molarity POGIL **HW: Per 0,4,6: Complete POGIL for Monday, CR review due Monday Constructed Response Gases on 4/28!! Agenda • Seat Change! • Review for tomorrow’s Gases CR • All KEYS are on my website • PowerPoint Notes are on my website • Extra Help Wednesday, C13 @ lunch **HW: study for Gases CR tomorrow, Study for Solutions Test Friday Agenda • Gases CR • You need a pencil, eraser and calculator • After test, pick up Lab and Study Guide **HW: Complete Pre-Lab for Thursday’s Kool-Aid Lab. Pre-Lab MUST be complete for you to participate in the lab. If it is not completed by Thursday, you will receive a ZERO for the lab! Agenda • Review problems to prepare for Friday’s test • Review Flyswatter! **HW: Study for Friday’s test, complete additional practice problems, Pre-Lab due tomorrow! If you don’t do it, you can’t participate! **Extra Help today @ lunch, C13 Agenda • Molarity of Kool-Aid Lab **HW: Study for test tomorrow, Study Guide for Enrichment, Complete Lab for Monday. Agenda • Solutions Test Today • There is NO notebook check! • Please turn in your study guide for enrichment • After your test, please pick up a reading. **HW: Complete reading and answer questions, complete Kool-Aid lab
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