Chemistry Day 62 · Do-Now: “Solutions CN B” 1. Write down today’s FLT: I will be able to...
Transcript of Chemistry Day 62 · Do-Now: “Solutions CN B” 1. Write down today’s FLT: I will be able to...
Chemistry Day 62 Wednesday, March 25th, 2020
Do-Now: “Solutions CN B” 1. Write down today’s FLT: I will be able to
identify the factors that determine the rate at which a solute dissolves by completing Solutions CN B
2. Why is water able to dissolve ionic compounds? Be as specific as possible.
3. Is ice more or less dense than liquid or gas water?
4. Define the word “solution”. 5. Explain if a glass of saltwater is a solution
or not.
Planner: • Study! I recommend re-doing practice
problems from notes and quizzes. • Write your name on today’s date in your
planner and send it to me on remind for extra dojos
Table of Contents #2: 14. Solutions CN B 15. Solutions WS B
FLT • I will be able to identify the factors that
determine the rate at which a solute dissolves by completing Solutions CN B
Standard HS-PS1-3:Planandconductaninvestigationtogatherevidencetocomparethestructureofsubstancesatthebulkscaletoinferthestrengthofelectricalforcesbetweenparticles.
Recall: Water is Polar
Recall: Like Dissolves Like • Polar/chargedmoleculesdissolveotherpolar/chargedmolecules
• Nonpolarmoleculesdissolveothernonpolarmolecules
• …So,what’sthedifference?
Solutions CN B: Properties of Solutions
Recall
Solvents and Solutes • Solution=homogeneousmixtureofsolvent+solute.
Homogeneous vs. Heterogeneous
Mixtures • Mixturesarecombinationsoftwoormoredistinctsubstances
• Mostnaturalsubstancesexistasmixtures– Ex/Evenwatercontainsimpurities,andthereforeexistsasamixture
Homogeneous vs. Heterogeneous • Homo=same,Hetero=different• Homogeneousmixture=uniformthroughout(solutions)– Ex/Saltwater,Air
Homogeneous vs. Heterogeneous • Homo=same,Hetero=different• Heterogeneousmixture=non-uniformthroughout(unevenlydistributed)– Ex/Saltwaterwithsandinit
Non-Homogeneous Mixtures
Mixtures that are NOT Solutions: • Suspensions=mixturesw/largeparticlesthatslowlysettle(ex/sandywater)– Particlesofasuspensionaregreaterindiameterthan1000nm.
– Canbeseparatedbyfiltering
Mixtures that are NOT Solutions: • Colloids=heterogeneousmixturesw/mediumsizeparticles
• Betweenthesizeofsuspensionsandtruesolutions(1-1000nm)
• Ex/Blood,milk
Dissolution
Dissolution • Recall-The“nature”(polarity,orcomposition)ofthesoluteandthesolventwilldetermine…– Whetherasubstancewilldissolve– Howmuchwilldissolve
Dissolution • Youareaddingsugartoyourtea,butyounoticethatit’snotdissolving.Whatdoyoudo?
Dissolution • Whichwoulddissolvefaster–asugarcube,orgranulatedsugar?
Dissolution • Ifwewanttoincreasetherateofdissolution,weneedtoincreasecontactbetweenthesoluteandsolventparticles
• Howcanwedothat?• FactorsAffectingtheRateofDissolution:
Dissolution 1. Stirring/Agitation
• increases contact between solute & solvent particles
Dissolution 2. Surface Area (of solute)
• Smaller pieces = more SA = more contact between solute and solvent
Dissolution 3. Temperature
• High T = Greater avg. KE = Particles move faster = more contact between solute and solvent
• High T can also increase the total amount of solute that will dissolve!
Saturation
Saturation • Solubility=maxamtofsubstancethat
willdissolveataspecifictemperature.• Units=gsolute/100gsolvent
Saturation • UnsaturatedSoln’=Canstilldissolve
moresolute– Ex/Solutecompletelydisappears
Saturation • SaturatedSoln’=Containsthemaxamt
ofsolutedissolved.
Saturation • SupersaturatedSoln’=Containsmore
thanittheoreticallycandissolve
Saturation and Equilibrium
Solute is dissolving
More solute is dissolving, but some is crystallizing
Saturation equilibrium established
Solubility
Solubility • éTemperature:
– ésolubilityforsolidsandliquids
• Ex/Sugarintea– êsolubilityfor
gases• Ex/Gasescapes
fromliquidwaterwhenboiling
Solubility • Whataboutpressure?• Henry’sLaw=Solubilityofagasina
liquidisdirectlyproportionaltothePofthegasabovetheliquid
– Ex/ When you remove the cap of a bottle of soda, you release pressure, and then the gas starts to escape
Solubility • Ofcourse,there’sanequation
Miscibility
Liquids • Miscible=Whentwoliquidscanmix/
dissolve– Waterandantifreezemixanddissolve
Liquids • Someliquidsareonlypartiallymiscible
– Ex/Waterandether
Liquids • Immiscible=Cannotmix/Dissolve
– Ex/Oilandvinegar
Pair-Share-Respond 1. Listthreefactorsthataffecttherateof
dissolution2. Explainhoweachofthosethreefactors
affectstherate3. Youaddasolute,andnoticethatitall
disappearsinthesolvent.Isthissolutionsaturated,unsaturated,orsupersaturated?
4. Ifyouincreasethetemperature,willasoliddissolvefasterorslower?
5. Ifyouincreasethepressure,willagasdissolvefasterorslower?
HW • SolutionsWSB• Study