SUMMARY

Th is exper iment o f s tudy ing the p roper t ies o f gas and l i qu id by us ing

Armf ie ld Proper t ies o f Gases and L iqu ids appara tus i s d iv ided in to

two par ts , wh ich a re Par t A and Par t B . Par t A i s conduc ted to

de te rmine the v iscos i t y o f a i r . The ma in techn ique o f th i s exper iment

i s to de te rmine the p ressure d rop by read ing the mercury leve l o f

manometer a t bo th s ides . I t i nvo lves c los ing the vacuum pump va lve

fo r every 10 seconds a f te r le t t i ng the con t ro l tap to exhaus t to

a tmosphere . The v iscos i t y o f gas , o r in th is con tex t , v i scos i t y o f a i r ,

i s de te rmined by us ing the Po iseu i l l e fo rmu la , s ta ted in Theory

sec t ion . The v iscos i t y o f a i r i s ca lcu la ted to be 1 .387x10 - 5 Ns /m 2 ,

wh ich i s 25 .83 percen tage o f e r ro r . The v iscos i t y o f gas i s then

p roved to be dependent o f p ressure , and i t i nc reases upon the

inc rease o f tempera tu re . Par t B i s conduc ted to de te rmine the

v iscos i t y o f l i qu id , in th is con tex t , g l ycer ine . I t i s bas ica l l y conduc ted

to record the t ime taken fo r a ba l l bear ing , wh ich i s denser than the

l i qu id , to fa l l a t a ce r ta in d is tance ins ide a v iscometer . The v iscos i t y

o f l i qu id i s de te rmined us ing S toke ’s Law o f d rag fo rce , and the

va lue o f v i scos i t y o f g lycer ine i s 5 .914 Ns /m 2 . The v iscos i t y o f l i qu id

however i s tempera tu re dependence , and i t i nc reases w i th a

decrease o f tempera tu re . The exper iment i s comple ted and

success fu l l y conduc ted .

1 | P a g e

INTRODUCTION

When a rea l f l u id f l ows , an ad jacen t layers move w i th d i f fe ren t

ve loc i t i es , where there a re f r i c t iona l fo rces tha t invo lves oppos ing

th is mot ion . Thus , d iss ipa t ion o f some o f the energy occurs . The

quan t i t y tha t descr ibes to what ex ten t th i s happens in a cer ta in f lu id

i s ca l led v iscos i t y der i ves f rom the La t in word “v i scum” fo r m is t le toe

(v i scous g lue , made f rom ber r ies and was used to coa t l ime- tw igs to

ca tch b i rds . V iscos i t y , o r common ly symbo l i zed as Ƞ i s a f lu id

p roper ty wh ich ind ica tes how res is tan t tha t f l u id i s to f l ow. V iscos i t y

p roper t ies can a lso be though t o f as an in te rna l res is tance to f low

p rocesses .

Indus t r ia l app l i ca t ions h igh ly depend on the p roper t ies o f the

mate r ia ls used such as v iscos i t y , dens i t y and d i f fus iv i t y . Ma jo r i t y o f

many p lan t opera t ions invo lved gases and l i qu ids .

A l though i t i s o f ten supposed tha t the thermodynamic

p roper t ies o f gases and l i qu ids a re known w i th accuracy su f f i c ien t

fo r v i r tua l l y a l l t echno log ica l purposes , th is i s no t in fac t the case .

A l though such p roper t ies can somet imes be es t imated f rom

thermodynamic mode ls , i t i s o f ten essen t ia l to measure key

p roper t ies in o rder to va l ida te o r op t im ise the ava i lab le mode ls .

Fur thermore , the deve lopment o f new mode ls i s dependent to a la rge

ex ten t upon the ava i lab i l i t y o f appropr ia te exper imenta l da ta .

2 | P a g e

AIMS / OBJECTIVES

The exper iment i s conduc ted in o rder to a t ta in a few ob jec t i ves

wh ich i s to de te rmine the v iscos i t y o f gases w i th p ressure d i f fe rence ,

to conc lude the dependency o f gases and l i qu ids w i th tempera tu re

and p ressure , to compare the theore t i ca l va lues o f v i scos i t y o f gases

and l i qu ids w i th exper imenta l va lues ob ta ined , to de te rmine the

v iscos i t y o f l i qu ids w i th bo th tempera tu re and p ressure d i f fe rence , as

we l l as to be ab le to ana lyze the e f fec t o f tempera tu re and buoyancy

on the p roper t ies .

THEORY

Viscos i t y i s the res is tance a mate r ia l has to change in fo rm.

H igh ly v i scous l i qu ids , l i ke moto r o i l o r mo lasses , take much longer

f l ow f rom the i r con ta iner than a re la t i ve ly low v iscos i t y l i qu id , l i ke

benzene o r d ie thy l e ther .   To quan t i f y v i scos i t y , we w i l l imag ine our

bu lk f l u id as cons is t ing o f a number o f ve ry th in layers .   In o rder fo r

the f lu id to f l ow, a fo rce w i l l be requ i red to s l ide these layers

re la t i ve to one ano ther .   The amount o f fo rce ( f ) requ i red i s assumed

to be d i rec t l y p ropor t iona l to the a rea ( A) o f the layers in con tac t

w i th one ano ther and the ve loc i t y d i f fe rence ( υ ) be tween the layers .

Fur thermore , the fo rce i s inverse ly p ropor t iona l to the d is tance ( d )

be tween the layers .   V iscos i t y ( η ) can then be in t roduced as a

cons tan t o f p ropor t iona l l y , y ie ld ing a fo rce equa t ion o f the fo rm

3 | P a g e

  . . . . . . . . . . . . . . . . . (1 )

D imens iona l ana lys is o f equa t ion (1 ) g ives S I Un i t s fo r

v i scos i t y o f kg m - 1   s - 1 .   However , the un i t tha t i s t yp ica l l y emp loyed

in p rac t i ce i s ca l led the 'po ise ' ( P ) , where 1  P  = 1 g ram cm - 1   s - 1 .  

L iqu id v iscos i t ies a re usua l l y repor ted in ‘ cen t ipo ise , ’   cP , and gas

v iscos i t y a re repor ted in ‘m ic ropo ise , ’  μP .  

The v iscos i t y depends on tempera tu re , dens i t y , and p ressure .

L ikew ise , in so -ca l led non-Newton ian f lu ids , the v iscos i t y a lso

depends on o ther fac to rs fo r ins tance ; so -ca l led th ixo t rop ic l i qu ids

such as ke tchup and concre te have a lower v iscos i t y when they a re

ag i ta ted . A t tempts to ca lcu la te v iscos i t ies f rom the s ta t i s t i ca l

p roper t ies o f the f lu id a re success fu l on ly fo r s imp le f lu ids (such as

nob le gases a t low p ressure ) . For these s imp le f lu ids , one f inds tha t

the v iscos i t y inc reases w i th inc reas ing tempera tu re . For mos t

l i qu ids , however , the tempera tu re dependence i s oppos i te , and the

v iscos i t y decreases w i th tempera tu re , as shown in the f igu re be low.

4 | P a g e

Viscos i t y in fac t i s bas ica l l y re fe r red to laminar f l ow. The

mo lecu les nex t to the sur face where a f lu id o r gas i s f l ow ing over i t

have zero speed . The speed inc reases w i th the d is tance f rom the

mo lecu les to the sur face . Th is d i f fe rence in speed shows the f r i c t ion

exer ted on the gas and l i qu id , where each mo lecu les be ing pushed

pas t each o ther . Thus , v i scos i t y de te rmines the amount o f f r i c t ion ,

wh ich in tu rn de te rmines the amount o f energy absorbed by the f low.

I t has been we l l known tha t the v iscos i t y o f l i qu id wate r

exh ib i t s d i f fe ren t behav iour f rom o ther o rd inary l i qu ids . Many

empi r i ca l equa t ions wh ich were app l ied to l i qu id wate r fa i led to

p red ic t the exac t va lue o f the v iscos i t y . However , some re fe rence

books show tha t the va lue o f v i scos i t y o f l i qu id i s 0 .3000 Ns /m 2 o r

0 .03 P . Meanwh i le , the va lue o f v i scos i t y o f a i r i s 1 .87 x 10 - 5 Ns /m 2

o r 1 .87 x 10 - 6 P .

On ly s ign i f i can t s t ruc tu re theory o f v i scos i t y had f i t ted the

v iscos i t y o f l i qu id wate r w i th success by assuming tha t the so l id - l i ke

5 | P a g e

vo lume was summed up to the mo le f rac t ion o f the i ce mix tu re . On

the o ther hand , the v iscos i t y o f wa te r vapour canno t be ca lcu la ted

success fu l l y by the p rev ious theory and any o ther v i scos i t y

equa t ions wh ich descr ibe the l i qu id s ta te . There fo re , no theory o f

v i scos i t y can be app l i cab le fo r bo th l i qu id wate r and wate r vapour .

There a re a few fac to rs tha t in f luence the v iscos i t y va lue o f a

f l u id . Cer ta in ly the s t reng th o f in te rmo lecu la r a t t rac t ions has an

in f luence ; n i t ro benzene has a much h igher v i scos i t y than regu la r

benzene because the fo rmer i s capab le o f d ipo le -d ipo le a t t rac t ions

wh ich a re cons iderab ly s t ronger than the d ispers ion fo rces o f

a t t rac t ion p resen t in bu lk benzene. Other fac to rs inc lude the s ize

and shape o f mo lecu les o f the respec t i ve f lu id .

As ment ioned ear l ie r , v i scos i t y va r ies w i th tempera tu re ,

genera l l y decreas ing as a tempera tu re i s inc reased . Th is occurs due

to the inc reased k ine t i c mot ion a t h igher tempera tu res p romotes the

b reak ing o f in te rmo lecu la r bonds be tween ad jacen t layers . A

cons iderab le amount o f research has been car r ied ou t in an a t tempt

to unders tand the exac t na tu re o f tempera tu re var ia t ion o f v i scos i t y .

One re la t i ve ly s imp le mode l assumes tha t the v iscos i t y obeys an

‘A r rhen ius - l i ke ’ equa t ion o f the fo rm;

. . . . . . . . . . . . . . . . . . . (2 )

where A and E a a re cons tan ts fo r a g iven f lu id . A i s ca l led the p re -

exponent ia l fac to r and  E a   can be in te rp re ted as the ac t i va t ion energy

fo r v i scous f low.   No te tha t th i s express ion i s near l y iden t i ca l to the

Ar rhen ius equa t ion tha t descr ibes the tempera tu re var ia t ion o f the

ra te cons tan t ( k ) o f a chemica l reac t ion , excep t equa t ion (3 ) does

6 | P a g e

not have a nega t i ve s ign in the exponent ia l wh ich causes the

v iscos i t y to ge t sma l le r w i th inc reas ing tempera tu re .

There i s a lso ano ther method o f ca lcu la t ion wh ich invo lves

v iscos i t y o f a l i qu id tha t f l ows in a cy l ind r i ca l tube . The theory tha t

i s a lso known as Po iseu i l l e ’ s Law is an express ion fo r the f low ra te

Q ( i n m 3 / s ) i n te rms o f the v iscos i t y Ƞ , t he rad ius R ( i n m) o f the

p ipe , i t s leng th L ( i n m) , and the p ressure d i f fe rence ∆p t u b e ( in Pa)

over the leng th o f the o f the f low;

Q = πR 4 ∆p t u b e

8ȠL . . . . . . . . . . . . . . . . . (3 )

When the f lu id en te rs the p ipe i t has to be acce le ra ted , and

energy conserva t ion requ i res tha t th i s i s assoc ia ted w i th a p ressure

d rop . Thus , on ly a f rac t ion o f the to ta l p ressure d i f fe rence ∆p

be tween in take and ou t le t o f the p ipe i s ava i lab le fo r ∆p t u b e . F rom

Bernou l l i ’ s Law and the fac t tha t the f low ra te i s the a rea o f the

c ross sec t ion t imes the average f low ve loc i t y v , o r Q = πR 2 v , one

der i ves eas i l y tha t

∆p t u b e = ∆p – ρQ 2 _

2π 2 R 4 . . . . . . . . . . . . . . . . (4 )

where ρ ( i n kg /m 3 ) i s the dens i t y o f the f lu id . Inser t ing Equat ion (4 )

in to Equat ion (3 ) and so lv ing fo r Ƞ , y ie lds the equa t ion we need to

ana lyze in th is exper iment ;

. . . . . . . . . . . . . . . . . . . . . (5 )

7 | P a g e

The re la t ionsh ip be tween t ime, t , and change in manometer

leve l can be ca lcu la ted by us ing the fo l low ing express ion ;

t =

8 LV ° μ

P A a4 π ln

(PA+P2 ) (PA−P1)(PA−P2) (PA+P1) .....................(6)

where t = t ime o f exper iment (s )

µ = v iscos i t y (Ns /m 2 )

L = leng th o f tube (0 .5 m)

V 0 = vo lume o f the vesse l (0 .0193 m 3 )

a = rad ius o f tube (0 .000575 m)

P 1 = in i t i a l p ressure (N /m 2 )

P 2 = f ina l p ressure (N /m 2 )

P A = A tmospher ic p ressure (N /m 2 )

The p ressure can be ca lcu la ted by us ing the fo l low ing express ion ;

P = ρgh . . . . . . . . . . . . . . . . . . . . . . (7 )

where ρ = dens i t y o f manometer f l u id (kg /m 3 )

g = acce le ra t ion due to g rav i t y (9 .81 m/s 2 )

h = he igh t o f mercury (m)

George S toke ’s Law o f V iscos i t y es tab l i shed the sc ience o f

hydrodynamics . I t i nvo lves se t t l i ng o f sphere and a lso der i va t ions o f

8 | P a g e

var ious f low re la t ionsh ips rang ing f rom wave mechan ics to v i scous

res is tance . S tokes came ou t w i th a fo rmu la tha t can p red ic t the ra te

a t wh ich a sphere fa l l s th rough a v iscous gas o r l i qu id .

As a mat te r o f fac t , the to ta l fo rces on a par t i c le mov ing in a

f lu id cons is t o f two par ts , wh ich a re sk in f r i c t ion and a lso d rag

fo rmat ion . Sk in f r i c t ion occurs due to the shear ing o f a l i qu id

whereas d rag fo rmat ion i s a resu l t f rom the fo rmat ion o f a wake

beh ind the par t i c le and cor respond ing d iss ipa t ion o f energy . Bo th

fo rces depend upon ra te a t wh ich the par t i c le i s t rave l l i ng . Sk in

f r i c t ion i s p redominan t in v i scous range wh i le d rag fo rmat ion i s

p redominan t in tu rbu len t range .

When a spher ica l par t i c le moves in a f lu id , i t w i l l acce le ra te

un t i l t he ne t downward fo rce i s ba lanced by the upward d rag fo rce .

Ne t t downward fo rce =

43π ( d3 )

3

( ps−p )g

=

π3d3( ps−p )

..................(8)

Net t upward fo rce = 3πȠdv

=

π3d3( ps−p )

......................(9)

9 | P a g e

Thus , the te rmina l se t t l i ng ve loc i t y laminar f l ow reg ion ;

V t =

d2g18 μ

( ps−p ) ................(10)

where d = d iameter o f sphere (m)

g = acce le ra t ion due to g rav i t y (9 .81 m/s 2 )

µ = v iscos i t y o f f l u id (kg /s .m)

ρ s = dens i t y o f sphere (kg /m 3 )

ρ = dens i t y o f f l u id (kg /m 3 )

Th is ve loc i t y i s te rmina l ve loc i t y the sphere w i l l a t ta in fa l l i ng

th rough the l i qu id o r gas . The equa t ion above works i f the mot ion i s

s low enough to keep the f lows in laminar domain . Once the speeds

inc rease pas t a l im i t , the d rag g rows a t la rge ra tes . Somet imes i t i s

necessary to f i gu re ou t i f t he dominan t va r iab le i s the v iscous f low o r

ine r t ia l f l ow.

10 | P a g e

EXPERIMENTAL PROCEDURE

Part A: Determinat ion of v iscosi ty o f gas

1. Th is exper iment i s se t up w i th the con t ro l tap c losed on the

cap i l l a ry tube .

2 . The vesse l i s evacua ted by open ing the vacuum con t ro l va lve to

i t s max imum l im i ts , and the p ressure d i f fe rence on the

manometer in mm Hg i s recorded .

3 . The vacuum pump va lve i s c losed and the con t ro l tap i s

exhaus ted to a tmosphere , th i s i s c losed a t 10 seconds in te rva ls

and the manometer read ing i s recorded .

Part B: Determinat ion of the v iscosi ty o f l iqu id

1. Ba l l bear ing i s a l lowed to fa l l d i f fe ren t known d is tance in a

ver t i ca ls co lumn o f l i qu id , he ld a t a cons tan t tempera tu re .

2 . The hea t ing f lu id i s s low ly c i rcu la ted th rough the tes t ce l l f rom

the thermos ta t i c ba th and i t s tempera tu re i s measured .

3 . The c i rcu la t ion o f f l u id th rough the tes t ce l l i s commenced f rom

the thermos ta t i c ba th a t a p rede te rmined low tempera tu re un t i l

t he tempera tu re reg is te red a t the top o f ce l l rema ins cons tan t .

4 . The thermometer i s then removed and a ba l l bear ing i s inser ted

in to the top o f v i scometer tube .

5 . The s top i s s ta r ted when the ba l l passes the top mark on the

co lumn and i s s topped when the ba l l passes the bo t tom mark .

6 . The d is tance be tween these marks i s p r in ted on the g lass and

the re la t i ve te rmina l ve loc i t y cou ld there fo re be de te rmined .

11 | P a g e

7. The dens i t y o f the f lu id and sphere mus t be de te rmined and the

v iscos i t y o f the f lu id a t the p rede te rmined tempera tu re i s

ca lcu la ted f rom the laminar f l ow re la t ionsh ips .

APPARATUS

Par t A : De te rmina t ion o f the v iscos i t y o f gas

1 . The Armf ie ld Proper t ies o f gases and l i qu id appara tus

2 . S topwatch

Par t B : De te rmina t ion o f the v iscos i t y o f l i qu id

1 . V iscometer

12 | P a g e

2. Vern ie r sca le

3 . S tand and c lamp

4. S topwatch

5 . Sphere bear ing

6 . G lycer ine (g lycero l )

RESULT

Par t A : De te rmina t ion o f v i scos i t y o f gas

T ime

(s )

Pressure , P 1

(h 1 )

P ressure , P 2

(h 2 )

P ressure d i f fe rence ,

∆P (mmhg)

ln (h 1 / h 2 )

0 445 158 287 1.035

10 415 188 227 0.792

20 389 214 175 0.598

30 367 236 131 0.442

40 350 253 97 0.325

50 337 266 71 0.237

60 327 276 51 0.170

70 320 283 37 0.123

80 315 288 27 0.090

90 311 292 19 0.063

13 | P a g e

Par t B : De te rmina t ion o f v i scos i t y o f l i qu id

H i g h o f

b a l l

b e a r i n g

f a l l i n g

( m m )

T i m e ( s )

1 s t r e a d i n g

T i m e ( s )

2 n d r e a d i n g

T i m e ( s )

3 r d r e a d i n g

T i m e ( s )

A v e r a g e

V e l o c i t y , v

( m / s )

2 2 0 4 . 8 5 6 . 2 2 6 . 0 6 5 . 7 1 0 . 0 3 9

2 0 0 4 . 5 6 7 . 0 6 5 . 7 8 5 . 8 0 0 . 0 3 5

1 7 5 5 . 6 8 4 . 1 3 4 . 2 5 4 . 6 9 0 . 0 3 7

1 0 0 1 . 5 9 2 . 0 6 2 . 4 7 2 . 0 4 0 . 0 4 9

2 5 0 . 7 2 0 . 5 6 0 . 6 8 0 . 6 5 0 . 0 3 9

Dens i t y o f g lycer in , ρ = 1261 kg /m 3

Dens i t y o f ba l l , ρ s = 1130631.213 kg /m 3

Diameter o f ba l l bear ing = 0 .6184 x 10 - 3 m

Mass o f ba l l bear ing = 0 .14 x 10 - 3 kg

SAMPLE CALCULATION

Par t A : De te rmina t ion o f v i scos i t y

Atmospher ic pressure ,P A

= ρgh

= 13580(kg /m 3 ) x 9 .81(m/s ) x 0 .76(m)

= 101247.048 (kg /s .m)

= 101247.048 (N /m 2 )

Pressure a f ter 10 seconds,P 1

= 13580(kg /m 3 ) x 9 .81(m/s ) x 0 .227(m)

= 30240.89 (kg /s .m)

= (101247.048 - 30240 .89) (N /m 2 )

14 | P a g e

= 71006.158 (N /m 2 )

Pressure a f ter 80 seonds,P 2

= 101247.048 – [13580(kg /m 3 ) x 9 .81(m/s ) x 0 .027 (m) ]

= 97650.118 (N /m 2 )

T ime, t

= ( t 2 – t 1 )

= 80s – 10s

= 70s

Thus , by app ly ing equa t ion (6 ) , the v iscos i t y o f a i r can now be

ca lcu la ted .

t =

8 LV ° μ

P A a4 π ln

(PA+P2 ) (PA−P1)(PA−P2) (PA+P1)

70 = ( (8×0.5×0.0193×μ )(101247.048× (0.000575 )4

×π ))ln

((101247.048+97650.118 )(101247.048−71006.158)(101247.048−97650.118 )(101247.048+71006.158))

µ = 1.387 x 10-5 Ns/m2

0 10 20 30 40 50 60 70 80 90 1000

0.2

0.4

0.6

0.8

1

1.2ln (h1/h2) versus time,t (s)

Time,t (s)

15 | P a g e

Ln (h1/h2)

Par t B : De te rmina t ion o f v i scos i t y o f l i qu id

Veloc i ty o f sphere

= average ve loc i t y

= (0.039+0.035+0.037+0.049+0.0395 )(m/s )

= 0 .0398 m/s

Thus , Vt

0.0398 =

d2g18 μ

( ps−p )

0.0398 = (( 0.6184×10−3 )2×9.8118 μ ) (1130631.213−1261 )

µ = 5.914 Ns/m2

SAMPLE ERROR CALCULATION

Par t A : De te rmina t ion o f v i scos i t y o f gas

The theore t i ca l va lue fo r v i scos i t y o f wa te r i s 1 .87x10 - 5 Ns /m 2 .

Never the less , the va lue ob ta ined f rom the exper iment has a

s ign i f i can t d i f fe rence w i th the theore t i ca l va lue , wh ich i s

1 .387x10 - 5 Ns /m 2 . Thus , we can ca lcu la te the percen tage o f e r ro r ,

as shown above .

16 | P a g e

Percen tage e r ro r = ((1.87×10−5 )−(1.387×10−5)1.87×10−5 ) (×100 % )

= 25 .83 %

DISCUSSION

The exper iment i s conduc ted based on a few ob jec t i ves wh ich

inc lude de te rmin ing the v iscos i t y o f gas and l i qu id and compar ing

i t w i th the theore t i ca l va lue as we l l as s tudy ing the e f fec t o f

tempera tu re and p ressure to the v iscos i t y o f gas and l i qu id .

The va lue o f v i scos i t y o f gas ca lcu la ted based on the

exper imenta l resu l t s i s 1 .387x10 - 5 Ns /m 2 . Never the less , th i s va lue

compr ises a lmos t 30 percen tage o f e r ro r f rom the theore t i ca l

va lue . There fo re , the re mus t have been a lo t o f m is takes and

e r ro rs dur ing the exper iment tha t lead to such e r roneous va lue .

F i rs t l y , the read ing fo r the p ressures on the manometer i s on ly

done once fo r each 10 seconds o f in te rva l . There fo re , we a re no t

ab le to ge t average va lue fo r each in te rva l in o rder to ge t more

accura te va lues .

Second ly , the manometer i s o ld and the sca le on th is

ins t rument i s overshadowed w i th co r ros ion , mak ing i t d i f f i cu l t to

read the mercury leve l on the lower p ressure s ide . Thus , the

read ing recorded may no t be the cor rec t and ac tua l va lues .

Th i rd ly , the va lve i s supposed ly c losed a f te r every 10 seconds

be fo re read ing the p ressures ind ica ted on the manometer .

17 | P a g e

However , i t may no t be c losed a t abso lu te ly a f te r the requ i red

in te rva l .

Nex t , the mercury leve ls observed on the manometer in

be tween 60 to 90 seconds a re vary ing up and down qu i te rap id ly ;

the re fo re i t i s d i f f i cu l t to observe the accura te read ing .

The v iscos i t y o f gas i s p ropor t iona l to the tempera tu re , thus as

the tempera tu re i s e leva ted , the v iscos i t y inc reases as we l l . Th is

i s in f luenced to the k ine t i c energy o f the gas mo lecu les . As

tempera tu re inc reases , the mo lecu les o f gas wh ich a re a l ready

fu r ther apar t tend to move rap id ly and thus , the k ine t i c energy

inc reases . The mo lecu les a re co l l i d ing w i th each o ther , and thus

the in te rmo lecu la r fo rces a re no longer neg l ig ib le . Hence , i t

conc ludes tha t the gas i s becoming more v iscous as the

tempera tu re i s ge t t ing h igher . However , v i scos i t y o f gas i s

depend ing on p ressure and no t tempera tu re . As what i s imp l ied

on Po iseu i l l e ’ s Law, the v iscos i t y i s based on the p ressure d rop .

Accord ing to mos t re fe rence books , the v iscos i t y o f l i qu id i s a t

approx imate ly 0 .300 Ns /m 2 . Th is i s way d i f fe ren t w i th the

exper imenta l resu l t ob ta ined , wh ich i s a lmos t 6 Ns /m 2 . However ,

as what has been ment ioned in Theory sec t ion ear l ie r , the

v iscos i t y o f l i qu id i s no t easy to be ca lcu la ted and the exac t va lue

i s d i f f i cu l t to be p red ic ted .

Dur ing the exper iment , i t i s becoming more d i f f i cu l t to record

the t ime taken fo r the ba l l bear ing to move pass the g lycero l a t

decreas ing d is tance requ i red . Th is i s due to the fac t tha t the

c loser the d is tance , the fas te r the ba l l bear ing to reach to the

bo t tom.

18 | P a g e

Next , the eyes o f the observer may no t be para l le l to the sca le

wh ich ind ica tes the d is tance requ i red to record the t ime taken fo r

the ba l l bear ing to reach the bo t tom. There fo re , the resu l t s

recorded a re a f fec ted as we l l .

When tempera tu re i s inc reased , the v iscos i t y o f l i qu id w i l l

dec reased . Th is i s because , the par t i c les o f l i qu id a re mov ing

away f rom each o ther . Thus , the v iscos i t y i s decreased , as the

ba l l bear ing i s mov ing fas te r . V iscos i t y o f l i qu id i s p roven to be

dependent o f tempera tu re .

CONCLUSION

The ob jec t i ves o f th i s exper iment i s sa t i s f ied w i th the va lue o f

v i scos i t y o f gas i s 1 .387x10 - 5 Ns /m 2 whereas the v iscos i t y o f

l i qu id i s 5 .914 Ns /m 2 . A l though the va lues a re d i f fe r ing much w i th

the theore t i ca l va lues , i t i s conc luded tha t v i scos i t y o f gas i s

depend ing upon tempera tu re . When tempera tu re inc reases , the

v iscos i t y a lso inc reases . On the con t ra ry , v i scos i t y o f l i qu id i s

decreas ing in inc reas ing tempera tu re . Thus , i t i s p ressure

depend ing , wh ich i s based on the p ressure d rop .

RECOMMENDATION

I n o rder to ge t more accura te va lue , the read ing fo r mercury

leve l i s necessar i l y taken to a t leas t th ree t imes . Bes ides tha t ,

the manometer shou ld be changed o r mon i to red p roper ly as i t i s

19 | P a g e

t he mos t impor tan t par t o f the appara tus . Th is goes the same w i th

the exper iment conduc ted in Par t B , where the t ime record ing

shou ld be done more than th ree t imes , a t leas t 7 read ings . Thus ,

the average va lue w i l l be more conv inc ing and minor m is takes

migh t no t a f fec t much on the ca lcu la ted va lue .

REFERENCE

* CHEMISTRY-THE CENTRAL SCEINCE (n in th ed i t ion ) -BROWN. LEMAY.BURSTEN

* A BREIF INTRODUCTION OF FLUID MECHANICS(seconds ed i t ion ) -DONALD F .YOUNG-BRUCE R.MUNSON-THEODORE H. OKI ISHI

* Cou lson & R ichardson (1997) , Chemica l Eng ineer ing (Vo l 1 ) , Pergammon Press

APPENDICES

20 | P a g e

21 | P a g e