The Properties of Water

The PropertiesofWater

Margaret E.Vorndam, M.S.Version 42-0129-00-01

LABREPORTASSISTANT                                                                                

Thisdocumentisnotmeanttobeasubstituteforaformallaboratoryreport.TheLabReport Assistantissimplyasummaryoftheexperiment’squestions,diagramsifneeded,anddatatables thatshouldbeaddressedinaformallabreport.Theintentistofacilitatestudents’writingoflabreports by providing this informationin an editable filewhichcan be sent to an instructor.

Exercise 1: SurfaceTension

RESULTS                                                                                                                    

A.  State yourhypothesis. What doyou think will happen?

B.   Record the results of your trials in the Data Table 1 above.

C.   Did the weight of the paper clip affectwhether it floatedor not? D.  Did the size of the paper clip affectwhether it floatedor not?

E.   Did the shape of the paper clip affectwhether it floatedor not?

F.    Optional:Did the additionof detergent influencethe flotationof the paper clip? Explain.

QUESTIONS                                                                                                                          

A.  Why must the paper clips, tweezers, and bowl be clean? B.   If one paper clip did not float,what might be areason?

C.   Was your original hypothesis supported or refuted?

DISCUSSION                                                                                                                          

A. Givetwoexampleswherethesurfacetensionofwaterisimportant.Whyisitimportantin these examples?

B.  Wouldotherliquidshavethesamesurfacetensionproperty?Whyorwhynot?Howmight you test this (for instance, the behavior of a paper clip and olive oil)?

C.   Is there a limit to the tensile strength of the water surface? Explain.

D.  What experimental variables are importantto consider when doing this exercise? E.   What is the purpose of this exercise?

Exercise 2: Capillary Action

RESULTS                                                                                                                          

A.  State yourhypothesis. What doyou think will happen? B.   Record the results of your exercise in the Data Table 2.

C.  Recordtheaverageresultsofatleastthreeotherstudents’exercisesinatablelikeTable3. Why is it important to note how many data sets (N) are used in the average?

N (number of data setsaveraged) =

D. GraphyourdataresultsfromTables1and2inascattergraph,linegraph,orbargraphsimilartothegraphlayoutinFigure1.Alsopresenttheaverageresultsoftheotherstudents’datausing asecondscatter, lineorbaronthesamegraphsothattheresultsofbothyourdataandotherstudents’datacanbecompared.Thegraphshouldpresenttwoseries ofdata, yourresultsand the average students’ results, with Capillary Tube Internal Diameter on the x-axis, and height of liquidon the y-axis. Note: Do the graph by hand, or you may use a graphingprogram, and copy the resultinggraphto your work area. Place your graph here:

E.  Whatistheadvantageofcomparingyourdatatothatoftheotherstudents’data?Whichset of data would you trust the most? Why?

My   data    from   Table   1    is   recorded   in           

(student    to    specify    color   of    line)

Otherstudents’averagedatafromTable2arerecordedin           (studenttospecifycolorof line)

QUESTIONS                                                                                                                          

A.  What did you observe at the end timeof the exercise?

B.   What caused the differencein the results that you obtained?

C.   How did your outcome compare to that of the other students?

D. WastherealinearrelationshipbetweenInternalDiameterandtheheightofthewater?What might explain this?

E.   Was your original hypothesis supported orrefuted?

DISCUSSION                                                                                                          

A.  Give two examples where the capillary actionofwater is important. Why is it important?

B.   Would other liquids have the same property? Why or why not? How might you test this?

C.  Bloodinourbodiestravelsthroughcapillariesofdifferinginternaldiameters.Thismeansthat ourheartcanworklesshard,sincebloodcontainswateraspartofthefluid, andthecapillary actionof water in tubes helps to move the blood along.

1.  Whydoesbloodpressureriseaspatientsexperiencetheprogressionofatherosclerotic disease?

Doesthisseemtobecountertowhatyouhavelearnedaboutcapillaryaction?Howdo you explain the apparent discrepancy (note: see also c., below)?

2.   Inplants,vascularsystemelementscalledxylemandphloemarelineduplikelongstraws fromthe rootofthe plant tothe leaves.Thexylem ofplants moves water anddissolved nutrients up to the leaves. Can you suggest what aids the movement of water up the plant, in additionto thecapillary actionof water?

3.   Why is it harder to suck a beverage through a small diameter straw than through a large diameterstraw?

4.   What experimental variables are important toconsider when doing this exercise? Whatcouldexplainthedifference inoutcomesbetweenyourdataandthedataofotherstudents?

5.   What is the purpose of this exercise?

Exercise 3: Density

RESULTS                                                                                                                          

A.  State your hypothesis. What do you think will happen?

B.   Record what actually happened here:

QUESTIONS                                                                                                                          

A.  What did you observe in this exercise?

B.   How does this outcome compare to what you observe about the actionof ice (the solidform of water) on liquidwater?

C.   Was your original hypothesis supported or refuted?

DISCUSSION                                                                                                                          

A.  Why is it important that ice floats?

B.   Give two examples where the property of water density is important.

C.   Do all solids floaton their liquid forms? Why or why not?

D.  The density of liquid olive oil is about 0.92. What canyou say about the likely density of solid oil? Why?

E.   Will olive oil floator sink if it is added to liquid water? Why?

F.    What experimental variables are important to consider when doing this exercise?

G. Attempttofindanotherpuresubstance,likewateroroil,inwhichthesolidformfloatsonthe liquid form (Note: do not spend more than 5 minutes on this question!).

H.  What did you learn from this exercise?

Exercise 4: SpecificHeat Capacity

RESULTS                                                                                                                          

A.  State your hypothesis. What do you think will happen?

B.  Whatdifferencedoyouobserveintheheightsofthefrozensolidoilandwaterascomparedto the liquid forms prior to freezing? What might explain this result?

C.   Record what actually happened in a table similar to Tables 4 and 5

D. GraphyourdataresultsfromTable4and5inagraphlikeFigure2.Useascattergraphor progressivelinegraph,withTimenotedonthex-axis,andmLofliquidcollectedonthey-axis.You shouldhavetwoscatter plotsorlinesonyourgraph(nottwoseparategraphs)—oneforwater andoneforoil.Note:youmayuseagraphingprogram,andcopytheresultinggraphtoyourwork area. Place your graph here:

E.  Calculatethemeltingrateforeachofwaterandoil.Themeltingrateisequaltotheslope ofeachofthe separatelinesofyourgraph,oneforwater, andoneforoil.Theeasiestwaytocalculatetheslopeforeachistouseyourgraphingprogram,andaskittodeterminethetrendlinefor you, as follows:

F.  Shareyourmeltingrateforwaterandtheoilwithotherstudents,ifpossible.Makesureto also obtain the ambient (room) temperature from the otherstudents. Why?

QUESTIONS                                                                                                                          

A.  Was your original hypothesis supported or refuted?

B.  Whatdoyouobserveconcerningtheplotlineoftheoilversustheplotlineofthewater? What does this mean?

C.  Howcloseisyourmeltingratetothemeltingratesreportedbyatleastthreeotherstudentsfor the water and for the oil?

D.  Generally,whatmightyouconcludeabouttheamountofspecificheatneeded tomelt50mL

of water versus 50 mL of oil?

E.   Howcould youexplainthedifferencesinyourdataobservationsastowhenthewaterandoil began to melt?

F.    Whatexperimentalvariablesareimportanttoconsiderwhendoingthisexercise?Whatcould explain the differencein outcomes betweenyour data and the data of other students?

DISCUSSION                                                                                                           

A. Howmightyoudesignasimilarexperimenttodeterminewhetherthespecificheat(amount of heat required to raise 1 gram of a material by 1 ºC) of one substance is more or less than anothersubstance?Whatvariablesmustyouconsiderinthedesignofyourexperiment?Give anexampleofsuchanexperimentthatcomparesthespecificheatsfortwodifferentsubstances.

B.   Analternative energy-savvypersondecidestouse55gallondrumsfilledwithliquidtowarm her house at night in the winter. She has to make a decisionaboutwhat liquidwillbe the most efficientatstoringheatfromsunlightthatshinesonthedrumsduringtheday.Shouldsheusewater or oil in the drums? Why?

LABORATORYSUMMARY                                                                                

What have you learned from doing this laboratory?