食品分析实验报告-4

이름:주이zhouyi

학과:식품영양학

학번:2009102110

Date:Mar.13.2011

Experimentaltitle:SolubilityofthesodiumchlorideinwaterandDilution

Purpose:Inthesamevolumeofwaterwereplacedindifferentpercentagesofsodiumchloride.Sothatitcangetinthewatersolubilityofsodiumchloride.Andthe3differentconcentrationsofsodiumchloridesaturatedsolution,unsaturatedsolution,supersaturatedsolutionweremarked.Unsaturatedsolutionthendilutedto5percentsodiumchloridesolution.

Procedures:

250mlcontainersinthepreparationof20percentsodiumchloridesodiumchloridesolution.

m/v=20g/100ml=x/250ml=>x=50g

Withascaletoweighout50gramsofsodiumchlorideinto250mlcontainers.

Distilledwaterandslowlystir.

50gSodiumchloridedistilledwater

4)Sodiumchloridedissolvedinwaterandchange20percentsodiumchloridesolution.

2.100mlcontainersinthepreparationof36percentsodiumchloridesodiumchloridesolution.

1)m/v=36g/100ml=x/100ml=>x=36g

2)Withascaletoweighout36gramsofsodiumchlorideinto100mlcontainers.

3)Distilledwaterandslowlystir.

36gSodiumchloridedistilledwater

Sodiumchloridedissolvedinwaterandchanges36percentsodiumchloridesolution.

3.250mlcontainersinthepreparationof40percentsodiumchloridesodiumchloridesolution.

1)m/v=40g/100ml=x/250ml=>x=100g

2)Withascaletoweighout100gramsofsodiumchlorideinto250mlcontainers.

3)Distilledwaterandslowlystir.

90gSodiumchloridedistilledwater

Thebottom40percentsodiumchloridesolutionofsodiumchloridestill.

4.To20percentoftheunsaturatedsolutionofsodiumchloridedilutedto5percentsodiumchloridesolution.

1)20%55x12.5=52.5ml

Ⅹ=>>50ml/(15+5)=12.5=>

01515x12.5=187.5ml

2)From20percentsodiumchloridesolution,52.5mlofsolutionpouredinto250mlcontainers.Andadd187.5mlofdistilledwaterinto250ml5%sodiumchloridesolution.

Results:Theexperimentsshowthat20percentofthesodiumchloridesolutionisunsaturatedsolution,36percentofthesodiumchloridesolutionissaturatedsolution,and40percentofthesodiumchloridesolutionissupersaturatedsolution.

20percentsodiumchloridesolutionfromtheextract52.5mlofsolutioninto250mlvolumetricflaskandthenpouredinto187.5mlofdistilledwater.Finally,becamea250ml5percentsodiumchloridesolution.

Discussions:Chemistryteachingexperimentiscomponentofaveryimportantandirreplaceablework.Therefore,toimprovethequalityofchemistryteaching,goodqualityandquantityisoneofthekeyexperiments.Ingeneraltheseexperiments,goodstability,repeatabilityisstrong.Buttherearealsosomeexperimentsareoftenaffectedbymanyfactorsasaresultoftheexperimentfailed.Sowhenweput36gramsofsodiumchloridedissolvedin100mlvolumetricflaskthenwefindthatthisexperimentisafailure.Because,accordingtothesolubilityofsodiumchloride,36gramsofsodiumchlorideshouldbecompletelydissolvedin100mlvolumetricflaskinasaturatedsolution.Butwhenweput36gramsofsodiumchlorideinto100mlvolumetricflasklaterfoundthat36gramsofsodiumchlorideisnotcompletelydissolvedinto100mlvolumetricflask.Onceagain,wedoexperimentsandtroubleshooterrorsfound36gramsofsodiumchloridein100mlvolumetricflaskcannotbedissolved.SoIthinkthetemperatureandsolidsodiumchlorideimpuritiesaffectedtheresults.Becauseatroomtemperature(20°)underthesolubilityofsodiumchlorideis36ml/100ml,butweareconductinglaboratoryexperiments,temperatureof20°sothedifferencedoesnotaffecttheexperimentalresults.

Conclusions:WhenconductingtheseexperimentsIsteppedonthesolute,solventandthesolutionconceptandunderstanding.Andonthesaturatedsolution,unsaturatedsolutionandsuper-saturatedsolutionthatisthefirstvisualimpressionandunderstanding.Whentheexperimentfailed,thefirstseriousexperimentalmethodsandenvironmentalfactorswerethinking.Theseareintheexperimentalprocessofexperienceandknowledgegained.Andthisisnotinabookorclassroomknowledge,onlyinthehandsaftertheexperimentwasdonetoobtain.

Date:Mar.13.2011

Experimentaltitle:Molarity,Dissolvedanddiluted

Purpose:Intheexperimenttounderstandthedifferencebetweenmolarityandmolality.Andweknowthatthefamiliarwiththemolaritycalculation.Dilutionmethodofstrengtheningtheunderstandingandoperationofproficiency

Procedure

1.Preparationof1molofsodiumhydroxidesolution.

Molarmassofsodiumhydroxide=Na(23)+0(16)+H(1)=40g/mol

Becausethesamepressurewiththetemperature:

V/V1=N/N1

NV1=N1V=>x1(L)=40*250(ml)=>X=40*250(ml)/1000ml

X=10g

1)

Withthebalancetoweighout10gramsofSodiumhydroxide

(Becausesodiumhydroxideisastrongalkalinesubstanceintheweighingprocesssopayattentiontosafety.)

Slowlyintotheflask

(Ifyouaccidentallyfellonthehandafterthefirstlotofwashinghandswithwaterandthencoatedwithanappropriateweakacid.)

2)

Slowlypourintoavolumetricflask

Pournotwater,becausewaterandsodiumtogetherwillhavesomeheatfortheexperimentalrisk.

Intothesolutionuntil250ml

(Preparationbecame1M/Lsodiumhydroxidesolution.)

2.to1M/Lsodiumhydroxidesolutionwasdilutedinto0.2M/Lsodiumhydroxidesolution.

NV=N1V1

1M/L*X=0.2M/L*250ml

X=0.2M/L*250ml/1M/L

X=50ml

From1M/Lsodiumhydroxidesolution50ml,pouredthesolution,andtheninto250mlvolumetricflask.

(Pourthesolutionintheprocessofattentiontosafetyandtoavoidsodiumhydroxidesolutiontothehand.)

Thengodowntohavethesodiumhydroxidesolutioninto50mlvolumetricflaskwherethesolutiontoaddupto250ml.

Finally,upanddowngentlyshakingtheflaskthesolutionevenly.

Results:Molarmassformulausedtocalculatethe1M/Lsodiumhydroxidesolution,howmuchsodiumhydroxide.Thenusetheformula1M/Lsodiumhydroxidesolutionneedtopourthenumberofmilliliters,todilutea0.2M/Lsodiumhydroxidesolution.Finalpreparationofthatisthe50ml,0.2M/Lsodiumhydroxidesolution.

Discussions:Preparationofsodiumhydroxidesolutionatthefirsttime,becausethereisnoconsiderationofthestrongalkalinesodiumhydroxidedilutedwithwatersodirectly.Causesalotofheatsodiumhydroxidesolution.Andweighinginwithabalanceofsolidsodiumhydroxideintheprocessbecauseofinadvert