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NAME: Akeem Bennett

DATE:

PRACTICAL #:

TITLE: RATE OF REACTION

AIM:To investigate the efect o a change in concentration o reactants on

the rate o reaction between sodium thiosulphate (Na2S2O! and h"drochloric

acid (#$l! and hence% determine the order o reaction&

APPARATUS/ MATERIALS:Stop watch% ' small beakers% measuring

c"linder% printed paper% &2) Na2S2Osolution% &') #$* solution% distilled

water&

DIAGRAM:

+,A-.A) S#O/,N- S0T1 O3

AA.AT1S 1S0+ ,N $ON+1$T,N- T#,S 040.,)0NT

METHOD:

5& The ollowing amounts o Na2S2O and #2O was measured and added into '

beakers&

6olume o Na2S2O 1sed 7cm 6olume o #2O 1sed 7cm

' 8 5 22

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5 8

2& The 9rst beaker was placed unto the printed paper and 5 cmo #$l was

added&

& The stopwatch was started immediatel" as the acid was added&

8& The print was observed rom above and the time it took or the print to

disappear was taken&

'& Steps 2 to ' were repeated with the other mi:tures o Na2S2Oand water&

;& The same method was then repeated using #$l instead o Na2S2Oand

5cm o Na2S2O was added each time&

VARIABLES:

)anipulated< $oncentration o reactants

.esponding< Time taken or print to disappear

$ontrolled< 6olume o the reactants

OBSERVATIONS/RESULTS:

TAB*0 S#O/,N- T,)0 TA=0N 3O. T#0 .,NT TO +,SA0A. 3O. 6A.>,N-

$ON$0NT.AT,ONS O3 Na2S2O

6olume o

Na2S2O

(cm!

6olume o #2O

(cm!

6olume o

#$l (cm!

$oncentration o

Na2S2O(mol7dm!

Time (s!

' 5 &2 5?8 5 5 &5; 2 2 5 &52 @2 5 &@ '85 8 5 &8 5?

TAB*0 S#O/,N- T,)0 TA=0N 3O. T#0 .,NT TO +,SA0A. 3O. 6A.>,N-

$ON$0NT.AT,ONS O3 #$l

6olume o

#$l (cm!

6olume o

Na2S2O

(cm!

6olume o

#2O (cm!

$oncentration o

#$l

(mol7dm!

Time (s!

' 5 &'

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8 5 5 &8 ; 5 2 & 52 5 &2 55 5 8 &5 5?

TAB*0 S#O/,N- .AT0 O3 .0A$T,ON 3O. SO+,1) T#,OS1*#AT0 AT

6A.>,N- $ON$0NT.AT,ONS

$oncentration o Na2S2O(mol7dm! .ate o .eaction (moldm7s!

&2 2&&5; '&&52 '&&@ 5&8 5

.ate o reaction or #$l was calculated as &2@2 moldm7s

CALCULATIONS:

The concentration o Na2S2O

$oncentration C moles7volume

)oles C molarit" : volume C &2 : '75 C &5 mol

6olume C '75 C &'dm

$oncentration C &57&' C &2mol7dm

The concentration o #$l

$oncentration C moles7volume

)oles C molarit" : volume C &' : '75 C & 2' mol

6olume C '75 C &'dm

$oncentration C &57&' C &' mol7dm

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DISCUSSION:

The graph o concentration against time or the sodium thiosulphate was a

curve depicting that as the concentration o sodium thiosulphate increased%

the less time was taken or the disappearance o the print& Also% as the

concentration o sodium thiosulphate increased so did the rate o reaction&

This is because as the concentration increases% the number o reactions that

can take place at a certain time is increased as more thiosulphate particles

would be present to collide and react with the acid& The curve obtained was

due to the order o reaction with respect to the thiosulphate% in which case

the reaction has been determined to be second order& This is so as the rate

o reaction doubled as the concentration o the thiosulphate doubled% thus%making it directl" proportional to the rate o reaction& The graph or var"ing

concentration o the acid (#$l! was a straight line& Based on the line obtained

the order o the reaction ma" considered Dero order& Thereore the overall

order can be considered to be 9rst&

PRECAUTIONS:

5& 0nsure to observe disappearance o the print rom directl" over the

Eask&2& The same person must be looking at the print

SOURCE OF ERROR:

5& #uman reaction error in the starting and stopping o the stop watch%

hence times obtained ma" not be e:actl" accurate&2& aralla: error ma" have occurred in the measuring o the various

volumes o solutions&

CONCLUSION:

Based on this e:periment% it can be concluded that as the concentration o

the reactants increases the rate o reaction increases& 3rom the results

obtained and best 9tline graphs drawn the order o reaction or sodium

thiosulphate was determined to be second and or h"drochloric acid Dero(!&

#ence% the overall order is 9rst&

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