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Rebecca Triano...

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Triano'CHE'111'F2019'

' Solutions:'Concentration,'Dilution,'and'Osmosis' ' 1.''Review'of'Solution'Formation:'For'each'of'the'following'compounds,'mark'whether'you'expect'it'to' dissolve'in'water'or'not.'For'those'compounds'that'do'dissolve'in'water,'write'the'balanced'chemical' equation'that'represents'how'they'dissolve.' ' ''''''''Does'it'dissolve?'(Y/N)' ' ' ' Y' ' NaCl'(s)''–––––>'Na+'(aq)'+'Cl–'(aq)' a.'' ' ' ' b.' ' N' ' CCl4'(l)' ' ' N' ' Gasoline'(CxHy)' c.'' ' ' ' d.' ' y' ' CH3OH'(l)'–––––>'CH3OH'(aq)'' ' ' y' ' CH3CO2H' (l)'+'H2O'–––––>'CH3CH2OO–'(aq)'+'H3O+'(aq)' e.' ' ' ' Y' ' Na3PO4' (s)'–––––>'3'Na+'(aq)'+'PO4 3–'(aq)' f.' ' ' ' ' 2.'Concentration:'' ' a.'In'general'(not'for'any'specific'units),'concentration'measures:'''amount'of''solute''''''''''''''''''d' ' ' ' ' ' ' ' ' ''''amount'of'solution' ' ' b.'Let’s'look'at'making'a'specific'solution:''a'2.0'M'solution'of'sodium'bicarbonate'(NaHCO3).'' ' ' i.'How'many'moles'are'in'a'liter'of'this'solution?'2.0'moles' ' ' ' ii.'To'make'100'mL'of'a'2.0'M'solution'of'NaHCO3,'you'might'place'0.20'moles'of'the'solid'in'a' ' 100'mL'volumetric'flask,'and'then'fill'it'to'the'line.' ' ' Why'wouldn’t'you'add'2.0'moles'to'the'flask'if'it’s'a'2.0'M'solution?' ' Only'making'a'tenth'of'a'liter,'so'add'1/10'*'2.0'moles'' ' ' ' Moles'can’t'be'measured'directly'in'the'lab'–'instead,'how'would'you'determine'how'much' ' solid'to'add?'Would'need'to'measure'grams'or'volume.'For'grams,'need'molar'mass' '

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Triano'CHE'111'F2019'

' ' Calculate'the'amount'of'NaHCO3'that'you'would'place'into'the'volumetric'flask'to'make'100'mL' ' of'a'2.0'M'solution.' ' .20'moles'x'40'g/mol'='0.80'grams' ' ' ' c.'Now'let’s'compare'multiple'units'of'concentration.' ' ' i.''What'is'the'%'m/v'concentration'(g/mL)'of'a'NaCl'solution'prepared'when'35'mg'of'NaCl'is' ' dissolved'to'a'total'volume'of'500.'mL'of'solution?'' ' ' 35'g/500.'mL'*'100'='7.0'%' ' ' ' ' ii.'What'is'the'molarity'(mol/L)'of'the'same'NaCl'solution?' ' 35'g'/'58.44'g/mol'='0.599'moles' ' ' .599'moles/'0.500'L'='1.2'M' ' ' ' iii.'Does'a'similar'solution'of'KI'(35'g'in'500.'mL)'have'the'same'%'(m/v)'concentration?'The' ' same'molarity?' ' Same'%'m/v'concentration'because'still'35'g'in'500'mL'but'different'molar'masses'='different' '' ' molarities' ' ' ' d.'Equivalents:'A'unit'often'used'in'medical'applications'to'measure'electrolytes'in'the'blood.'An' equivalent'of'an'ion'is'the'amount'needed'to'make'1'mole'of'positive'or'negative'charge.' ' So:'''1'mol'Na+'='1'Eq'Na+','but'1'mol'Ca2+'='2'Eq'Ca'2+','and'1'mol'PO43–'='3'Eq'phosphate' ' So,'if'a'patient'has'a'blood'calcium'level'of'4.8'mEq/L,'what'would'that'calcium'level'be'in'molarity?' ' ' 4.8'mEq/L'='0.0048'Eq/L'='0.0024'mol/L' ' ' ' What'if'instead,'the'patient’s'blood'calcium'level'was'not'given'in'Eq,'but'in'mg/dL?'Convert'7.4'mg/dL' into'molarity,'remembering'our'guidelines'for'dimensional'analysis.' ' *$& *+$'( *$%,!.#$%& = $0.0018$𝑀' $𝑥$$ $𝑥$ $𝑥$ ' '(

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Triano'CHE'111'F2019'

' e.'For'a'solution'with'a'concentration'of'0.000045'g/mL'(m/v),'express'the'concentration'as'a'%m/v,'a' ppm,'and'a'ppb.'Which'concentration'is'easiest'to'report'because'it'has'the'fewest'zeros?' ' ' %'m/v'='0.0000045'x'100'='0.0045' ' ' ppm'='0.0000045'x'1,000,000'='4.5'ppm'(easy'to'report)' ' ppb'='0.0000045'x'1,000,000,000'='4500'ppb'' ' ' ' ' 3.'Dilution:'When'diluting'solutions,'the'number'of'moles'doesn’t'change,'only'the'concentration'and' the'volume!' ' a.'A'student'transferred'50.'mL'of'a'2.5M'aqueous'sodium'hydroxide'stock'solution'to'a'500.mL' volumetric'flask'and'added'water'to'the'fill'mark.'What'is'the'molar'concentration'of'the'solution'she' prepared?' ' ' 50.'mL'x'2.5'M'='500'mL'x'C2' ' C2'='0.25'M' ' ' ' ' b.'Nipride'is'a'medication'for'patients'in'heart'failure.'You’re'preparing'an'IV'solution'for'a'patient'that' should'have'a'concentration'of'50.'mg/250'mL.'' ' ' i.'You’re'given'a'vial'from'the'pharmacy'with'a'concentration'of'25'mg/mL'and'have'access'to'as' ' much'saline'solution'to'dilute'it'as'you'need.'How'would'you'prepare'the'IV'solution?' ' You'need'50'mg,'so'using'dimensional'analysis,'you'take'2'mL'of'the'solution'from'the'pharmacy' ' ' vial'and'dilute'it'to'a'total'volume'of'250'mL' ' ' ' ' ii.'The'patient'is'receiving'their'Nipride'solution'by'IV'at'a'rate'of'60.'mL/hr.'How'many'hours' ' will'the'patient'be'undergoing'an'infusion'for?' ' ' 4.16'hours'or'4'hours,'10'minutes' ' ' ' ' iii.'How'many'milligrams'of'Nipride'per'hour'is'the'patient'receiving?' ' 50'mg/250'mL'x'60'mL/h'='12'mg/hr' ' ' ' ' '

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Triano'CHE'111'F2019'

' ' 4.'Osmosis:'' ' a.'We'said'in'the'last'problem'that'Nipride'is'being'diluted'by'a'saline'solution.'This'saline'solution'is' 0.90'%(m/v)'NaCl'(aq).'Translate'this'concentration'into'a'conversion'factor.' b.'Red'blood'cells'have'a'concentration'of'0.90'%(m/v)'NaCl,'which'is'why'we'use'this'in'IVs.'When'red' blood'cells'are'immersed'in'0.90%'saline'solutions,'they'maintain'their'shape.'Otherwise,'water'will' travel'in'or'out'of'the'cell'membrane,'swelling'or'shrinking'the'cell.' ' ' i.'What'would'happen'if'the'red'blood'cells'were'placed'in'a'10%'saline'solution?' ' ' ' Water'would'rush'out'to'reduce'the'concentration'of'the'10%'solution'and'the'cell'' ' ' would'crenate'(shrink)' ' ' ii.'What'would'happen'if'they'were'placed'in'DI'water,'which'has'no'ions'in'it?' ' ' Water'from'the'DI'water'would'rush'in'to'equalize'concentration,'and'it'would'swell'and' ' ' ' ' burst' ' ' c.'For'each'of'the'solutions'separated'by'a'selectively'permeable'membrane,'shown'below'before' osmosis:' ' i.''Label'each'solution'as'hypertonic,'hypotonic,'or'isotonic.' ''''' ii.'Indicate'the'direction'in'which'water'will'diffuse'across'the'membrane,'if'at'all,'as'a'result'of' ' osmosis.' '''' iii.'Indicate'which'solution'will'increase'in'volume,'after'osmosis,'if'at'all.' '

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A:'Water'flows'from'right'to'left,'increasing'the'volume'of'soln'A' Soln'A'begins'as'hypertonic'to'B'(more'solute)'

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B:'Soln'A'begins'as'hypertonic,'gains'volume'until'concentrations'equalize'

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Triano'CHE'111'F2019'

' d.'Dialysis:'A'dialysis'membrane'separates'mixture'A'from'pure'water,'as'shown'in'the'diagram'on'the' left.'Mixture'A'contains'urea'(small'circles),'a'small'neutral'molecule,'and'albumin'(large'circles),'a' protein'(a'colloid).'' ' ' i.'Show'what'the'two'compartments'will'look'like'after'dialysis'in'the'diagram'on'the'right.'Does' ' urea'cross'the'membrane?'Does'albumin'cross'the'membrane?'How'do'the'concentrations' ' compare'after'dialysis?' '

' ' ' ' ii.'What'could'you'do'to'remove'more'urea'from'mixture'A?' ' ' Need'the'right'solution'to'have'a'decreased'concentration'–'can'replace'with'fresh' ' water'by'flowing'new'water'through'' ' ' ' e.'Identify'the'type'of'transport'(passive'diffusion,'facilitated'transport,'or'active'transport)'that'will' occur'for'the'following'molecules:' ' ' i.'oxygen'Passive' ' ' ' ii.'glucose,'no'energy'required''Facilitated' ' ' ' iii.'Na+,'energy'required''Active' ' ' Active' ' iv.'K+,'no'energy'required'' ' ' f.'For'iii'and'iv'above,'is'the'ion'going'into'or'out'of'the'cell?'Refer'to'the'concentration'gradient'chart'in' the'slides!' Na'requires'energy:'going'from'less'to'more'(out'of'the'cell)' ' ' ' ' K'is'spontaneous:'going'from'higher'to'lower'(also'out'of'the'cell)'

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