REPORT

KINETICS CHEMICALS



CHAPTER I

1.1. TITLE

Chemical Kinetics

1.2. DAY / DATE M

1.3. PRACTICAL OBJECTIVES

A. Measures changes in the concentrations of reagents by time

B. Observe the effect of concentration, temperature, and catalyst on reaction rate

C. Determining the rate laws of a reaction in an aqueous solution

 CHAPTER II

. Theoretical basis

Reaction rate measurement is an amazing chemical field. From kinetic studies, the mechanism of the reaction can be reduced. Information about the reaction of catalysts and inhibitors can only be obtained through kinetic assessment.

The rate of a chemical reaction can be affected by several factors:

· Reactant concentrations (and sometimes products)

· Temperature

· Catalyst

Rate measurements are usually performed under fixed experimental conditions, with one fixed factor whereas other factors are varied. When the influence of these factors on the rate has been determined, these factors are fixed and other factors are varied. Systematic assessment of rate dependence on reaction rate changes is continued until the kinetic behavior of the reaction is complete.

How to measure the rate of reaction, one important aspect of kinetic assessment is to design an easy technique to monitor the course of the reaction over time. Chemical analysis by means of volumetry or gravimetry is relatively slow, so this way is not in use unless the reaction is slow, or can be stopped by sudden cooling, or by the addition of reactants that stop the reaction.

Some commonly used ways are to use the nature of color and conductivity. The reaction rate involving the gas is determined by measuring the volume of time union gas. In this experiment you use a color change.

To a hypothetical reaction

2A + 3B à C + 5D

The law of its speed can be

Where k is the rate constant; N is the reaction order for A; And m is the reaction order for B. The overall reaction order is n + m. The order of the reaction can only be determined by experiment, since these numbers are not always the same as the reaction coefficient (stoichiometry).

In this experiment you will perform a reaction between sodium thiosulfate with hydrochloric acid.

S2O3-2 + 2H + à SO2 + H2

The rate of this reaction depends only on the concentration of S2O3-2, but not on the acid concentration. This is evidenced from the graph 1 / t against (S2O3-2) which gives a straight line. This graph implies that the order of reactions is one for thiosulfate. And because the acid concentration does not affect the rate. The rate of the org is zero.

You will also experiment with a two-order reaction for one of the reacting components. Second order can be inferred when a straight line is formed from graph 1 / t against [HCl] 2.

(Basic Chemistry lab guide, 2011: 71-72)

CHAPTER III

3.1. TOOLS AND MATERIALS

· Tools

1. Erlenmeyer

2. Stopwatch

3. Pipette drops

4. Sandpaper Steel

5. Pumpkin

6. The reaction tube

7. Measure Glass

8. Watershed

·         Material

1. Tiosulfate solution

2. Water

3. Hydrochloric Acid

4. Na2S2O3

5. HCl

6. Mg Band

7. Oxalic acid

8. Sulfuric acid

9. KMnO4

10. H2SO4

.3. OBSERVATION DATA

A. Order of reaction in the reaction of Sodium thiosulfate with hydrochloric acid

Observation on the effect of Na-thiosulfate concentration

Na2S2O3 (ml)

Na2S2O3 (M)

H2O (ml)

HCl (ml)

T (seconds)

1 / t (seconds-1)

25

0.15

-

4

127

0.00787

20

0.12

5

4

160

0.00625

15

0.09

10

4

198

0.00505

10

0.06

15

4

286

0.00349

5

0.03

20

4

319

0,000313


The reaction order is 1 for Na2S2O3

Observation on the effect of hydrochloride acid concentration

Na2S2O3 (ml)

H2O (ml)

HCl (ml)

[HCl] (M)

T (seconds)

1 / t (seconds-1)

25

-

5

2.0

78

0.0128

25

2

3

1.8

96

0.0104

25

4

1

0.6

102

0.0098


B. Order of reaction in magnesium reaction with hydrochloric acid

Observation on the effect of hydrochloride acid concentration

[HCl] (M)

HCl (ml)

T (seconds)

1 / t (seconds-1)

[HCl] 2

Log [HCl]

Log (1 / t)

0.6

100

414

0.002415

0.36

-0,221

-2,617

0.8

100

343

0.002898

0.64

-0.0960

-2,537

1.0

100

202

0.004545

1.44

0

-2,342

1.2

100

130

0.00769

1.44

1.08

-2,114

1.4

100

88

0.01136

1.96

1.15

-1,945

1.6

100

55

0.01818

2.56

1.20

-1,740

1.8

100

40

0.025

3.24

1.25

-1,602

2.0

100

25

0.04

4

1.30

-1,398

The reaction order is 1 for Hcl

C. Effect of temperature on reaction rate

Reaction time at various temperatures (sec)

Deuteronomy


Reaction Temperature

1000C

500C

250C

1

2s

13s

33s

2

2s

13s

33s

Average

2s

13s

33s

Signs of reaction: a change of color to a clear white

D. Effect of catalyst on reaction rate


Deuteronomy

H2SO4

2ml

1ml

0ml

1

2minutes 33sec

12min 4sec

23mn 90sec

2

2minutes 41sec

15 minutes

24 mins 15sec

Signs of reaction:

A) 2ml → purple disappears (purple-purple-red liver-orange nodes) heat reaction

B) 1ml → purple disappear (purple-purple-red liver-orange nodes) heat reaction

C) Purple, fixed homogeneous solution

DISCUSSION

A. Order of reaction in reaction of sodium thiosulfate with hydrochloric acid


In this experiment we observed a reaction order between the thiosulfate solution and hydrochloric acid. In the determination of the order of this reaction is closely related to the rate of reaction. In general, the rate of reaction is defined as the change in reagent concentration and reaction product per unit time. Chemically, the rate of the reaction is determined by determining the concentration of the substances at a given time, then the concentration data is used to calculate the reaction rate.

In this experiment, we can determine the reaction order of each reaction reactor according to the reaction rate data. For reactions:

Na2S2O3 (aq) + 2HCl (aq) à2NaCl (aq) + SO2 (g) + S (s)

In this experiment the thiosulfate solution was mixed with water, then hydrochloric acid was added. After mixing homogeneously, the experiments as listed in Table 10.1 and the results of the observations are as follows:
) 25 ml of Na2S2O3 with 0.15 M mixed with 4 ml of HCl. Within 127 seconds the solution has shown turbidity, due to the deposition of sulfur. In this first experiment the compound did not add water to the sodium thiosulfate. This incorporates a faster mass to appear entirely in the solution when added with water or not with water.

B) 20 ml of Na2S2O3 with 0.12 M mixed with 5 ml of H2O, then added with 4 HCl. Within 160 seconds the solution has shown turbidity, due to sulfur deposition at the bottom of the erlenmeyer tube.

C) 1.5 ml of Na2S2O3 with 0.09 M mixed with 10ml H2O, then added with 4 ml of HCl. In 198 seconds the solution has shown turbidity, due to the deposition of sulfur at the bottom of the erlenmeyer tube.
D) 10 ml of Na2S2O3 0.06 M mixed with 15 ml of H2O, then added with 4 ml of HCl. Within 286 seconds the solution has shown turbidity, due to the deposition of sulfur at the bottom of the erlenmeyer tube.

E) 5ml Na2S2O3 0.03 M mixed with 20 ml of H2O, then added with 4 ml of HCl. Within 319 seconds the solution has shown a turbidity due to sulfur precipitation at the bottom of the test tube.


Theoretically, for experiments with the mixed compositions listed in Table 10.2, we only searched for the order of reactions alone and calculated the overall reaction order.

Order of reactions in the reaction of magnesium and hydrochloric acid

For reaction = Mg (s) + 2 HCl (aq) àMgCl2 (aq) + H2 (g)

The treatments given in this reaction are:
A) Comparison of various HCl concentrations (0.6 M; 0.8 M; 1.2 M; 1.4 M; 1.6M; 1.8M; and 2M). At the same volume of HCl and react the Mg band into the test tube. The observation result of bubble gas and magnesium dissolve in HCl until exhausted in a certain time.

B) Magnesium takes several minutes to dissolve in HCl where the speed depends on the concentration of the HCl.

C) The rate of reaction is influenced by varying HCl concentrations.

For example, the reaction rate equation is formulated by r = k [Mg] [HCl], the rate of reaction depends only on the solution phase [HCl] so that the reaction order to Mg is zero.
Effect of temperature on reaction rate

As has been known before that the temperature rise accelerates the reaction, otherwise the decrease in temperature will slow the reaction. In the case of reaction rates: A2 + B à 2AB has the equation: r = k [A] m [B] n

The temperature change has k, since its value depends on the temperature and the type of reaction. If the temperature is raised, the amount and energy of collisions between reagent molecules increases.


B. Effect of catalyst on reaction rate

A slow reaction can be accelerated by giving / adding other substances without adding concentration or temperature. The substance is called a catalyst. The catalyst usually reacts temporarily and then re-forms as a free agent. Next reacts again with the reactant speeding up the reaction and free again. So on and on over and over again.
A reaction using a catalyst is called a catalyst reaction and the process is called catalysis. The catalyst of a reaction is usually written over an arrow. Example:

2KCl (g) MnO2 2KCl (s) + 3O2 (g)

. CONCLUSION

From the experiments conducted, it can be deduced:

· The effect of time on the change of reagent concentration is the more time, the reagent concentration decreases.

· Effect of temperature, concentration and catalyst on the reaction rate, the higher the temperature in the reaction, the faster the reaction rate will be. Similarly with concentration, the greater the concentration the faster the reaction rate, and the more the catalyst inserted into a reaction the greater the concentration the reaction rate will accelerate.

· A reaction using a catalyst is called a catalyst reaction and the prosenya is called catalysis. By phase, the catalyst can be divided into two: homogeneous and heterogeneous catalysts


3.8. BIBLIOGRAPHY

Epinur, dkk.2010.P Basic Chemical Practical Guide.Jambi: Jambi University

Hiskia, A and Tupamalu. 1992. Electrochemistry and Chemical Kinetics. Bandung: ITB

Petrucci, Ralph H.1987. Basic Chemistry Principles and Applied Modern Volume 2.Jakarta: Erland

Syukri S, 1999. Basic Chemistry 2. Bandung: ITB