Teacher's/Lecturer'sSheet
Printed:30.03.201717:35:01|P7158900
Preparationandpropertiesoflimewater(magnesium
hydroxidesolution)(ItemNo.:P7158900)
CurricularRelevance
AreaofExpertise:
Chemie
EducationLevel:
Klasse7-10
Subtopic:
SäurenundBasen,
Protonenübergänge
Topic:
AnorganischeChemie
Experiment:
Herstellungund
Eigenschaftenvon
Kalkwasser
(Magnesiumhydroxidlösung)
Difficulty
PreparationTime
ExecutionTime
RecommendedGroupSize
Easy
10Minutes
10Minutes
2Students
AdditionalRequirements:
ExperimentVariations:
Keywords:
limewater,magnesiumhydroxidesolution,materialproperty,preparationoflimewater
Taskandequipment
Informationforteachers
Learningobjectives
Calciumandmagnesiumreactwithwatertoformalkaline-earthhydroxideswhileatthesametimeissuinghydrogen.
Theaqueoussolutionofsuchhydroxidesshowsthetypicalpropertiesofanalkalinesolution.Calciumhydroxidesolution
alsoreferredtoaslimewaterisusedforindicatingthepresenceofcarbondioxide.
Notesonset-upandprocedure
Preparations
Getsomecarbondioxidetakenfromasteelcylinderreadyorsetupanapparatusforpreparingcarbondioxide,forinstanceon
thebasisofmarble.
Magensiumreactsmorevigorouslywhenithasbeenactivatedbymeansofsomeiodinebeforehand.
Remarksonthestudents'experiments
Makesurethattheheatingprocedureisstoppedwhenthemagnesiumstartstoreactwiththewater.If,however,thereaction
shouldstopagain,heatingcancontinueforashortperiodoftime.
HazardandPrecautionarystatements
Phenolphthalein:
H226:
P210:
P233:
Flammableliquidandvapour.
Keepawayfromheat/sparks/openflames/hotsurfaces.-Nosmoking.
Keepcontainertightlyclosed.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
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Teacher's/Lecturer'sSheet
Printed:30.03.201717:35:01|P7158900
Magnesium,
powder:
H260:
H250:
P210:
P402+P404:
Incontctwithwaterreleasesflammablegaseswhichmayignitespontaneously.
Catchesfirespontaneouslyifexposedtoair.
Keepawayfromheat/sparks/openflames/hotsurfaces.-Nosmoking.
Storeinadryplace.Storeinaclosedcontainer.
Calcium,granular:
H261:
Incontactwithwaterreleasesflammablegases.
P402+P404:
Storeinadryplace.Storeinaclosedcontainer.
Hazards
Calciumhasacorrodingeffectontheskin.Donottouchitwithbarefingers!
Calciumreactsvigorouslywithwaterwhilereleasinginflammablegases.Magnesiumiseasilyinflammable!
Putonprotectiveglasses!
Notes
Thisreactionofthealkaline-earthmetalswithwatercorrespondstothatofalkalinemetals.Inthiscase,alkalinesolutionsand
hydrogenareformedlike,forinstance,
Mg+2H2O→Mg(OH)2+H2
Remarksonthemethod
Thisexperimentshouldbeprecededbyademonstrationexperimentshowingthereactionofalkalinemetalsinananalogueway.
Thisallowstodrawthestudents'attentiontothediagonalrelationship(periodictable)ofthereactivitybetweenalkalinemetals
andalkaline-earthmetals.Thedifferenceinreactivitycanthenbeexplainedbymeansofthenumberofouterelectronsandthe
numberofshells.
Wastedisposal
Filteroutthemagnesiumresiduesandletthemreactcompletelyafterheatingthem.Addthecalciumhydroxidesolutioninthe
beakertothelimewaterorputitintothecollectingtankforacidsandalkalistogetherwiththemagnesiumhydroxidesolution.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201717:35:01|P7158900
Preparationandpropertiesoflimewater(magnesium
hydroxidesolution)(ItemNo.:P7158900)
Taskandequipment
Task
Whatarethepropertiesofalkalinesolutionsofcalciumandmagnesium?
Prepareasolutionofcalciumhydroxide(alkalinesolutionofcalcium)andasolutionofmagnesiumhydroxide(alkalinesolutionof
magnesium)andstudytheirproperties.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
www.phywe.com
Student'sSheet
Printed:30.03.201717:35:01|P7158900
Equipment
PositionNo.
Material
OrderNo.
Quantity
1
Protectingglasses,clearglass
39316-00
1
2
Testtuberackfor12tubes,holesd=22mm,wood 37686-10
1
3
Washbottle,250ml,plastic
33930-00
1
4
Spatula,powder,steel,l=150mm
47560-00
1
5
Tweezers,straight,blunt,160mm
64610-02
1
6
Glasstubes,straightwithtip,10
36701-63
(1)
7
Pipettewithrubberbulb
64701-00
1
8
Glassrod,boro3.3,l=200mm,d=5mm
40485-03
1
9
Rubbertubing,i.d.6mm
39282-00
1
11
Testtube,18x188mm,10pcs
37658-03
(3)
12
Testtubeholder,uptod22mm
38823-00
1
Butaneburnerf.cartridge270+470
47536-00
1
ButanecatridgeCV300Plus,240g
47538-01
1
Calcium,granular50g
30049-05
1
Magnesium,powder100g
30133-10
1
Water,distilled5l
31246-81
1
Phenolphthalein,0,5%soutioninethanol,100ml
31715-10
1
Additional
material
Carbondioxide
Robert-Bosch-Breite10
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Student'sSheet
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Set-upandprocedure
Set-up
Hazards
Calciumhasacorrodingeffectontheskin.Donottouchitwithbarefingers!
Calciumreactsvigorouslywithwaterwhilereleasinginflammablegases.Magnesiumiseasilyinflammable!
Putonprotectiveglasses!
Procedure
Filltheglassbeakertwothirdsfull(Fig.1)andthetesttubecompletelyfullwithdistilledwater(Fig.2).Sealthetesttubewith
yourthumb(Fig.3)andplaceitwiththeorificedownintotheglassbeaker(Fig.4).Makesurethatnowaterleaksoutofthetest
tube.
Fig.1
Fig.2
Fig.3
Fig.4
Usethetweezerstoput10grainsofcalciumthroughtheorificeofthetesttubeintheglassbeakersothattheyascendinside
thetesttube(Fig.5).Whenthetesttubeisfilledwihgas,takeitoutofthebeakerandholditwiththeorificetowardstheflame
oftheBunsenburner(Fig.6).Makesurethatthecalciumresiduesremainintheglassbeaker.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
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Student'sSheet
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Fig.5
Fig.6
Fillthetesttubehalffullwiththesolutionformedinthebeaker(Fig.7)andaddsomedropsoftheindicatorsolution(Fig.8).Use
theglasstubetoaddsomecarbondioxidetotheresidualsolutionintheglassbeaker(Fig.9).
Fig.7
Fig.8
Fig.9
Fillaspatula-tipfullofmagnesiumpowderintothethirdtesttube(Fig.10)andfillitonequarterfullwithdistilledwater(Fig.11).
Addsomedropsofphenolphthaleinsolution(Fig.12)andheatthetesttubecarefullyuntilareactiontakesplace(Fig.13).
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
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Student'sSheet
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Fig.10
Fig.11
Fig.12
Fig.13
Wastedisposal
Letthemagnesiumreactcompletely.Putthecontentofallvesselsintothecollectingtankforacidsandalkalis.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
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Student'sSheet
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Report:Preparationandpropertiesoflimewater(magnesium
hydroxidesolution)
Result-Observations(10Punkte)
Writedownyourobservationson
thereactionofcalcium.
thereactionofmagnesium.
Evaluation-Question1(10Punkte)
Drawtheconclusionsfromyourobservations:
Robert-Bosch-Breite10
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Evaluation-Question2(10Punkte)
Describethereactionsobservedintheformofawordequation.
Evaluation-Question3(10Punkte)
Summarizethewayofproducingalkalinesolutionrepresentedinthisexperimentintheformofageneralcatchword.
Robert-Bosch-Breite10
D-37079Göttingen
Tel:+49551604-0
Fax:+49551604-107
[email protected]
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Student'sSheet
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Evaluation-Question4(10Punkte)
Underwhichnameandforwhatpurposehasthecalciumhydroxidesolutionalreadybeenused?
Robert-Bosch-Breite10
D-37079Göttingen
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Fax:+49551604-107
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