chem111 postlabexpt1.doc

7/27/2019 chem111 postlabexpt1.doc

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Reporter: Jaimee Navarro Instructor: Sir AgbayaniSection: 1-1 Date Performed: August 18 !"1"#roup No$: % Date Submitted: August !& !"1"

'(periment 1: )easurements

INTRODUCTION

)easurement is necessary in ma*ing +uantitative observations$ It isdefined as t,e determination of t,e magnitude of a certain +uantity bycomparison it, its standard$ .ne needs to ma*e accurate measurements tomaintain re/iabi/ity of resu/ts$ Accuracy is t,e /eve/ of c/oseness of t,ee(perimenta/ va/ue to t,e true va/ue$

Density is t,e ratio of mass to vo/ume for a given substance$ In t,ise(periment e i// be ab/e to /earn ,o to measure t,e mass vo/ume anddensities of so/ids and0or /i+uid substances it, ,ig, accuracy and proper

app/ication of significant figures$

METHODOLOGY

o get t,e density of ater first one s,ou/d eig, a c/ean dry &" m2graduated cy/inder$ ,en add appro(imate/y !" m2 of disti//ed ater in t,egraduated cy/inder and record its eig,t$ So/ve for t,e mass of t,e /i+uid bysubtracting t,e mass of t,e graduated cy/inder it, ater from t,e mass of t,egraduated cy/inder it,out ater$

o compute for t,e density of a /i+uid ot,er t,an ater eig, an empty'r/enmeyer f/as*$ Add 1"$" m2 of t,e un*non /i+uid in t,e f/as* using t,e

pipette and record its eig,t$ .btain t,ree tria/s and t,en get t,e average$ Ne(tso/ve for its density using t,e formu/a stated above$

,e density of ood can be ac+uired by measuring t,e /engt, idt, and,eig,t of t,e ood t,en eig,ing it direct/y on t,e ba/ance pan$

2ast/y t,e density of an irregu/ar/y s,aped so/id can be attained by usingt,e ater disp/acement met,od$ 3irst eig, t,e ob4ect and t,en immerse it in a&" m2 graduated cy/inder fi//ed it, !& m2 of ater$ Read t,e fina/ vo/ume$

5a/cu/ate t,e densities of ater /i+uid samp/e ood and irregu/ar/ys,aped so/id using t,e formu/a: D6m07 ,ere D6density of t,e ob4ect m6massof t,e ob4ect and 76vo/ume of t,e ob4ect$ ,e percentage error can becomputed by using t,e formu/a:

9 error 6 e(perimenta/ va/ue ; t,eoretica/ va/ue ( 1""9t,eoretica/ va/ue

A// observations and computations ere proper/y and systematica//yrecorded$


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TREATMENT OF RESULTS

I$ Density:A$ $ 2i+uid Samp/e:1!?$? g @$& g 6 "$@& g0m2-1!1$! g 1"$" m2 @$& g mass of /i+uid samp/eB

5$ $ 2i+uid Samp/e:"$@& g0m2 ; "$@@ g0m2 ( 1""9 6 1$&9

"$@@ g0m2

DISCUSSION OF RESULTS

o read t,e graduated cy/inder /oo* up to t,e unit ,ere it is mar*ed offand t,en estimate one more p/ace$ ,erefore 1"" m2 graduated cy/inder can beread to t,e nearest "$1 m2 and t,e 1" m2 graduated cy/inder can be read to t,enearest "$"1 m2$ If t,ere is app/ication of significant figures t,e estimatednumber ,as uncertainty so rounding off i// be done to cance/ t,e estimatednumber$ ,is is to ensure accuracy of resu/ts$ ,e /ast decima/ p/ace e canmeasure to get t,e eig,t of t,e substance by using t,e p/atform ba/ance is tot,e nearest "$"1 g$ App/ying significant figures t,e measurement obtained i// berounded off to t,e tent,s p/ace$


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,e density of t,e ,uman body may be obtained by eig,ing t,e ,umanbody and using t,e ater disp/acement met,od to obtain its vo/ume$ .nee(amp/e on ,o to use t,e ater disp/acement met,od for t,e ,uman body is byusing a simming poo/ measuring t,e vo/ume of t,e ater in it and t,enca/cu/ating t,e difference in vo/ume of t,e ater ,en a ,uman dives in t,e poo/$

If I ere as*ed to guess its density I ou/d assume t,at it is 4ust about t,e sameas t,at of ater because it may sin* or f/oat in it depending on t,e vo/ume of airin its /ungs$

o determine t,e density of a so/id ,ic, is so/ub/e in ater first eig,t,e so/id$ Ne(t use a graduated cy/inder and fi// it it, a certain vo/ume of adenser /i+uid ,ere t,e so/id i// not disso/ve in$ P/ace t,e so/id into t,e cy/indert,en record t,e difference in vo/ume of t,e /i+uid$ ,is vo/ume can no be usedto get t,e density of t,e so/id$

CONCLUSION AND RECOMMENDATION

>ased on t,e resu/ts e can no confirm t,at t,e e(periment as doneit, ,ig, accuracy because t,e percentage errors obtained ere sma//$ oobtain ,ig, accuracy t,ere are many factors to consider /i*e t,e proper use andmaintenance of measuring devices$ Significant figures can a/so ,e/p attainaccuracy$

3rom t,e e(periment e ere a/so ab/e to prove t,at if t,e density of acertain substance is greater t,an 1 it i// f/oat in ater$ If t,e density of t,esubstance is /ess t,an 1 it i// sin* in ater$

,e e(periment can be improved furt,er by ensuring t,at a// materia/s and

apparatus used are c/ean and fo//oing t,e procedure correct/y$

REFERENCES

1$ >ron $ 2e)ay '$ >ursten >$ 5,emistry: t,e centra/ science C t,ed!""= Pearson 'ducation0Ne Jersey p$ 1@-!&

!$ ,e 5o/umbia 'ncyc/opedia @t,ed !""8 5o/umbia Eniversity Press

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chem111 postlabexpt1.doc