Unit 11 Solutions- Guided Notes. What are alloys? What is the difference between heterogeneous and homogeneous mixtures?

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1 Name: Perid: Unit 11 Slutins- Guided Ntes Mixtures: What is a mixture and give examples? What is a pure substance? What are allys? What is the difference between hetergeneus and hmgeneus mixtures? Slutins: What is a slutin? Slute= Slvent= S, if I mix cream int my cffee, which is the slute and which is the slvent? Once the slute is evenly disslved, what d yu call the new cffee? Characteristics f Slutins: List sme characteristics and prperties f slutins: States f Matter f Slutins: Slutins are cnsidered t be in state f matter but can be made up f any cmbinatin f states f matter fr their and Can yu think f an example f each? Liquid in a Liquid: Gas in a Liquid: Gas in a Gas: Slid in a Liquid: Slid in a Slid: Slubility: refers t a slute s ability t be disslved by the slvent. A substance is if it is able t be disslved in a given slvent. A substance is said t be if it stays in its riginal state in the slvent (aka it des nt disslve) Liquids that disslve in ne anther are called and liquids that d nt disslve in ne anther are called 1

2 Slubility and Plarity: means having ppsite ends (a end and a end) substances include: inic cmpunds, acids, and plar cvalent cmpunds substances include: nn-plar cvalent mlecules and diatmic mlecules Water is a substance Like disslves like substances disslve ther substances substances disslve substances will nt disslve and vice versa Water is the (meaning it can disslve mst substances) because it is Why d yu think that il and water wn t mix? is nn-plar, s it is able t disslve grease. Disslving: Remember: plar substances, like inic cmpunds and water, are cmpsed f a end and a end There are 2 phases f disslving: - the prcess f attractin and assciatin f mlecules f a slvent with mlecules r ins f a slute - Separatin f slute mlecules and spreading f slute thrugh slutin with mre slvent surrunding Fr example when sdium chlride (NaCl) disslves in water, sdium chlride separates int sdium ins and chlrine ins in the slutin Describing Slutins: Cncentratin= What is the difference in dilute and cncentrated? Saturatin: D yu think yu culd disslve a whle bag f sugar in a cup f water? Why r why nt? What is a saturatin limit? Can saturatin limits change? Hw? What is a saturated slutin? Hw can yu tell a slutin is saturated? What is an unsaturated slutin? Hw can yu tell a slutin is unsaturated? What is a supersaturated slutin? Hw des a slutin becme supersaturated? Hw can yu tell a slutin is supersaturated? 2

3 Slubility Curves: A slubility curve is a representatin f slubility f substances Slubility curves shw hw much f a can be disslved in 100g r 100mL f at a given temperature What happens t slubility f a substance as temperature increases? D any substances break this rule? Why? On a slubility curve, the indicate the cncentratin f a saturated slutin the amunt f slute that will disslve at that specific temperature. Values n the graph a curve represent unsaturated slutins - slute culd be disslved at that temperature. Answer the questins and include units 1. Which slute is mst sluble at 10 C? 2. Which slute is least sluble at 40 C? 3. Hw much slute is in a saturated slutin f ammnia at 25 C? 4. If KNO 3 has 70g f slute disslved at 60 C is the slutin saturated, unsaturated, r supersaturated? 5. If a slutin f NaCl has 20g f slute disslved at 90 C is the slutin saturated, unsaturated, r supersaturated? Rate f Disslutin: Rate f disslutin is hw smething disslves If yu are making sme sweet tea and yu are trying t disslve a lt f sugar, hw can yu make the prcess f the sugar disslving faster? 3 factrs affect the rate f disslving:,, and 1. - the disslving prcess ccurs at the surface f the slid being disslved. The mre surface expsed the the disslving. Which wuld disslve faster: a cube f sugar r crushed sugar? 2. - agitatin such as,, r remves newly disslved particles frm the slid surface and cntinuusly expses the surface t fresh slvent higher temperature causes the slvent t mve mre rapidly, thus increasing the rate f disslving fr, but decreasing the disslving rate f a. Slubility fr decrease when temperature is increased because the mlecules mve t and escape rather than disslve b. This is shwn n a slubility curve by 3

4 Measuring Cncentratin: A slutin r a slutin is a slutin whse cncentratin is accurately knwn. There are multiple ways t measure cncentratin mathematically : (very similar t percent cmpsitin) : has t d with acids and bases : imprtant fr clligative prperties : the mst cmmn way t express cncentratin Mlarity Mst cmmnly used expressin f cncentratin Mlarity (M)= Number f f slute disslved in a liter f slutin Represented by and units are (Mlar) T make a 1M slutin f aqueus NaCl, measure 1 mle (which has a mass f 53g) f NaCl and add 1 Liter f water. 1 mle /1 L = 1 Mlar (M) Mlarity Practice: 1. If 5.7 g KNO 3 was disslved in 233 ml f water, what is the mlarity f the slutin? (Hint yu have t cnvert grams t mles and ml t L) 2. What is the mlarity f a slutin that cntains 42g f KCl in a 7.98L sl n? 3. Hw many grams f NaOH are required t prepare 200mL f a 0.45M slutin? 4. Hw many liters f a 0.85M slutin f sdium sulfate cntains 0.35 mles f sdium sulfate? 5. Hw wuld yu prepare 0.55 L f a 0.7M slutin f sdium chlride? 6. Hw wuld yu prepare 800 ml f a 1.2M slutin f lithium hydrxide? Clligative Prperties: is the number f particles a slute breaks int when it disslves. is a prperty that is dependent nly n the number f slute particles present in slutin (aka depends n the mlality and dissciatin factr) Examples f clligative prperties are and An increase r decrease in cncentratin will effect clligative prperties 4

5 When cncentratin is increased The freezing pint is always this is called freezing pint depressin And the biling pint is always this is called biling pint elevatin Which wuld freeze faster a 0.50M slutin f salt water r a 1.0M slutin f salt water? Which wuld bil faster? Why d we salt the rads when is snws? When salt is added t the rads the cncentratin (increases/decreases). This causes the (freezing pint/biling pint) t (increase/decrease). This helps because Why d we add salt t the pt f biling water when we ck ndles? When salt is added a pt f biling water when cking ndles the cncentratin (increases/decreases). This causes the (freezing pint/biling pint) t (increase/decrease). This helps because Dilutins: If yu made a slutin f sweet tea (slute= and slvent= ), if it was nt sweet enugh, hw culd yu increase the cncentratin? If it was t sweet, hw culd yu decrease the cncentratin? is the prcess f adding t a slutin t the cncentratin f slutin The actual number f mles f the slute never changes Only the amunt f slvent changes t reduce the f the slutin. The pictures t the right shw a slutin thrughut a dilutin prcess: 1. Which slutin is the mst cncentrated? 2. Which is the mst dilute? 3. What happens t the vlume as we dilute the slutin? 4. What happens t the amunt f slvent thrughut the dilutin? 5. What happens t the amunt f slute thrughut the dilutin? 6. What happens t the cncentratin f the slutin thrughut the dilutin? Dilutin Calculatins: When yu need t dilute a slutin, yu knw 3 f the fllwing 4 things: the mlarity f what yu started with ( ), the new mlarity f the slutin yu want t make ( ) The vlume f the slutin yu start with ( ) The vlume f the new slutin ( ) Use the dilutin equatin M 1V 1= M 2V 2 t slve fr the last variable. Vlume can be in units f r. 1. Calculate the mlarity that results when 250 ml f water is added t 125 ml f.251 M HCl. 2. Suppse yu wished t make a L f M aqueus silver nitrate by dilutin a stck slutin f a 0.675M aqueus silver nitrate. What will the vlume f the stck slutin wuld yu need t use? 3. Calculate the new cncentratin when 50.0mL f water is added t 735mL f 1.25M NaCl. 4. Hw much water wuld need t be added t 750mL f a 2.8 M HCl slutin t make a 1.0M slutin? 5