THE
RATE OF REACTION
A.
Objective: Determine the reaction rate equation.
B.
Basic theory:
The reaction rate as a measure that states the reduced number of substances - substances reagent per unit time or increase in substance - the substance of reactions per unit time. Changes in the concentration of a substance - a substance in a chemical reaction usually affects the rate of reaction. The equation shows the influence of the reaction rate systematically. The reaction order is part of the reaction rate equation based on the concentration of substances - substances reagent. In general, the reaction rate
depends only
on the initial concentration of the substance - the substance of reagents which can be determined by experiment. For the reaction A + B C + D, then the reaction rate equation can be expressed as follows :
V
= k[A]m . [B]m
V
= reaction rate (M s-1)
K
= constanta of reaction rate (L mol-1 s-1 )
M
= rection level ( reaction orde ) for A
N = rection level ( reaction orde ) for B
[A]
= the initial concentration of A ( mol L-1 )
[B]
= the initial concentration of B ( mol L-1 )
Total reaction rate is the sum total of all the reagents
the reaction rate. Reaction rate zero (0) means the rate of reaction is not
affected by the concentration of reactants, but only at the price tetgantung
reaction rate constant (k). Price (k) depends on the temperature, if the
temperature is fixed price (k) is also fixed.
In this experiment the reaction rate will be determined against the reagent to the reaction between Sodium Thiosulfate and Acid Chloride, according to the equation:
In this experiment the reaction rate will be determined against the reagent to the reaction between Sodium Thiosulfate and Acid Chloride, according to the equation:
Na2S2O3
(aq) + 2HCl(aq)
2NaCl(aq) + SO2(aq) + S(s) + H2O(l)
C. Tools and Materials :
1.
HCl solutions
2.
Na2S2O3 solutions
3.
Chemical Glasses
4.
Pipet
5.
Stopwatch
6.
Glass beaker filled with water
7.
Paper
D. Work Steps :
1. Record the time since the addition of 0.2 M Na2S2O3
solution of 20 ml into 10 ml 2 M HCl solution until no sightings by observing a
cross (X) of black ink on paper that is under the venue for the reaction
beaker.
2.
Repeat the experiment using a more dilute Na2S2O3
solution such as table 1.
3.
Repeat the experiment using a more dilute
solution of HCl in table 2.
E. Experiment
Result
Table 1
Volume HCl
|
Volume (ml)
|
Concentration (mol/l)
|
Time
|
1/time
|
||
2M (ml)
|
Na2S2O3
|
Water
|
Sum of
|
Na2S2O3
|
(second)
|
|
(0,2 M)
|
Volume
|
on initial reaction
|
||||
10
|
20
|
-
|
30
|
0.2 M
|
32
|
0,03
|
10
|
15
|
5
|
30
|
0.15 M
|
43
|
0,02
|
10
|
10
|
10
|
30
|
0.10 M
|
69
|
0,01
|
10
|
5
|
15
|
30
|
0.5 M
|
195
|
0,005
|
Table 2
Volume Na2S2O3
|
Volume (ml)
|
Concentration (mol/l)
|
Time
|
1/time
|
||
0,2M (ml)
|
HCl
|
Water
|
Sum of
|
HCl
|
(second)
|
|
(2 M)
|
Volume
|
on initial reaction
|
||||
20
|
10
|
-
|
30
|
2 M
|
43
|
0,03
|
20
|
7.5
|
2.5
|
30
|
1.5 M
|
37
|
0,03
|
20
|
5
|
5
|
30
|
1 M
|
33
|
0,03
|
F. Question
1.
Make The graph of 1/time for Na2S2O3 concentration
!
How much the
reaction orde of Na2S2O3 concentration ?
2.
Make The graph of 1/time for HCl concentration !
How much the
reaction orde of HCl concentration ?
3.
Write down the reaction rate equation and the reaction
equation !
4.
How much the total of the reaction orde ?
5.
Mention the Factors which influences the reaction rate
with the example!
The Answer
1. Concentration
of Na2S2O3
Include the reaction orde of 1
2.
Concentration of HCl
Include the
reaction orde of 0
3.
The reaction rate equation
v = k. [Na2S2O3]1.
[HCl]0
v = k. [Na2S2O3]1
The reaction
equation :
Na2S2O3
(aq) + 2HCl(aq)
2NaCl(aq) + SO2(aq) + S(s) + H2O(l)
4.
The total reaction orde
= m + n
= 1 + 0
= 1
5.
The factors which influences the reaction rate
Concentration:
chemical reactions take place faster or greater rate of reaction if the
concentration of a substance that reacts
example: metal zinc (Zn) with a solution of hydrochloric acid (HCl), the rate of reaction is influenced by the concentration of HCl is also affected by the condition of metallic Zn
Surface area: the surface area of the touch area of the reactants, the faster the reaction rate
example: in the fields of industry, manufacture of gas by reacting potassium asitilen carbide with water
Temperature: the chemical reactions take place more rapidly at high temperatures. The more kinetic energy of a substance - a substance that reacts increases.
example; gaseous oxygen and nitrogen in the air at ordinary temperature does not react with each other. However, if there is lightning, O2 and N2 gases react with each other to form oxygen-nitrogen
The catalyst: the catalyst will cause the reaction takes place in several stages. Slowest reaction steps in a reaction mechanism is the rate determining step of the reaction.
example: Ni is used to catalyze the hydrolysis process (the direction in the manufacture of margarine Ni can not be used unuk mengakatalis KClO3 decomposition into KCl and O2
example: metal zinc (Zn) with a solution of hydrochloric acid (HCl), the rate of reaction is influenced by the concentration of HCl is also affected by the condition of metallic Zn
Surface area: the surface area of the touch area of the reactants, the faster the reaction rate
example: in the fields of industry, manufacture of gas by reacting potassium asitilen carbide with water
Temperature: the chemical reactions take place more rapidly at high temperatures. The more kinetic energy of a substance - a substance that reacts increases.
example; gaseous oxygen and nitrogen in the air at ordinary temperature does not react with each other. However, if there is lightning, O2 and N2 gases react with each other to form oxygen-nitrogen
The catalyst: the catalyst will cause the reaction takes place in several stages. Slowest reaction steps in a reaction mechanism is the rate determining step of the reaction.
example: Ni is used to catalyze the hydrolysis process (the direction in the manufacture of margarine Ni can not be used unuk mengakatalis KClO3 decomposition into KCl and O2
G. Conclusion:
of these experiments, found that the reaction rate
equation of
Na2S2O3
(aq) + 2HCl(aq)
2NaCl(aq) + SO2(aq) + S(s) + H2O(l) is v = k.[ Na2S2O3]
From the reaction
rate, influences include some faktr, namely temperature, surface area,
concentration, and catalyst
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