USING ENGLISH TO REPORT

SCIENTIFIC OBSERVATIONS AND STOIKIOMETRY

CHAPTER 1

PRELIMINARY

1.1 Background

If we talk about chemistry, surely we will remember the atoms, the molecular elements, and the changes or reactions that occur between them. Chemical elements can be found in both free and non-existent and some artificial. The elements are usually denoted by letters which stands for the element's name. These elements can also be formulated.

Chemical reactions can be found everywhere for example that is not far from us, for example in our body there is a chemical reaction, for example our body fluids consisting of chemicals in ions. In our body there is also the process of digesting food with the help of enzymes and combustion process.

In this experiment 1, it will be tested and discussed on scientific observations and stoichiometry: KClO3 measurements. Scientific observations are related to the scientific method. Scientific method is a step or a way to get a truth from the observations made. The scientific method uses three steps: scientific theory, hypothesis and experimentation. In general the stages undertaken are finding problems or observations, collecting data, submitting hypotheses, conducting experiments, drawing conclusions and writing scientific reports. Stoichiometry learns about chemical calculations that connect magnitudes or units of atoms that can be measured laboratoryally. Stoichiometry studies about the atomic period, the number of particles, moles, percent mass, empirical formulas and molecular formulas, and stoichiometric applications in life. The chemical reaction of the dilam can be measured by the chemical equation called the concept of mole. For example, calculate the amount of CO2 emitted by 2 literbensin burned in a motor vehicle.

1.2 OBJECTIVES

1.      Gain experience in recording and explaining experimental observations.

2.      Develop skills in handling glass tools and transferring solid or liquid chemicals.

3.      Familiarize yourself with the safety procedures in laboratory work.

4.      Determine the KClO3 reaction coefficient coefficient.

5.      Calculates the molar volume of oxygen gas in STP state.

6.      Calculates the percentage of O2 in KClO3

CHAPTER II

THEORETICAL BASIS

Chemistry is a branch of science that studies the material and its changes. Fundamentally, science is scientific knowledge systematically compiled through a carefully designed series of experiments, careful observations, to conclusions drawn with cendika. This procedure, known as the scientific method, involves three steps, namely the legal or scientific theory of hypotheses and experiments (Drs.Epinur, 2015: 17).

Chemistry is classified as a science that specifically studies material changes, both chemical and physical changes. Material change is a major study in chemistry, because material change is a natural phenomenon that needs to be studied and understood in order to be made. Changes to the favorable. Material change is always accompanied by changes in energy in the form of heat (Yayan Sunarya, 2010: 2).

Chemistry is built by two pillars of study that support each other, so that chemistry develops until now and develops until the end of time. The two pillars are theoretical and empirical studies. Both pillars of the study were used to develop chemistry using systematic steps called the scientific method. In its simplest form, the scientific method consists of the observation stage, searching for patterns based on observation, theoretical formulation, theory testing and conclusion (Yayan Sunarya, 2010: 3-4).

Stoichiometry is a study of the mass of a chemical species in a chemical reaction quantitatively. Stoichiometry is based on 3 chemical laws, namely:

a.       The law of conservation of mass of substances before and after the reaction is the same. (Lavoiser law)

b.      Comparative law remains: on a chemical compound the mass ratio of each constituent compound is fixed. (Proust's law)

c.       The law of multiple comparisons: if two elements form a compound then the mass ratio of each constituent of the compound is a simple number. (Djulia Onggo, 2013: 3)

Stoichiometry relates to quantitative relationships between elements in a compound and between substances in a reaction This term comes from the Greek language, namely stoicheon and metrain. Stoicheon means element and metrain means measure. The basis of all stoichiometric calculations is the knowledge of atomic mass

CHAPTER III

PRACTICAL METHOD

3.1 Tools and materials

Tools:

1. Florence flask

2. Copper metal

3. Pumpkin erlemenyer

4. 150ml cup glass

5. Filter paper

6. Glass watch

7. Passengers

8. Cup

Material :

1. Blue solution (10 grams glucose in 300 ml KOH 0.5 m and 10 ml 0.1 g methyl blue solution)

2. Concentrated nitric acid

3. Sugar

4. 15 ml of concentrated sulfuric acid

5. 40 ml of ethanol

6. Clean water

7. 3.9 ammonium sulfate

8. Zinc powder

9. Ammonium chloride

10. Calcium chloride

3.2 Work Procedures

Scientific observation

A. Demonstration by assistant

a. The blue color disappears

110g blue glucose solution in 300 ml 0.5 ml KOH and 10 ml of methyl blue solution, Included in Florence flask, threaded and shaken once with lid held by thumb, Repeated experiment 2 to 3 times

b. Black foam

Granulated sugar Put into a 150 ml cup of glass until half filled 15 ml of concentrated sulfuric acid Added into a glass cup Stirred carefully with a glass stirrer

c. heat

40 ml of ethanol and water Entered into 150 ml cup glass, saringiambi paper and soaked in alcohol solution, Excess solvent squeezed and stretched on a watch glass, then burned

CHAPTER IV

RESULTS AND DISCUSSION

4.1 RESULTS AND DISCUSSION

1. Scientific observation

A. Demonstration by assistant

1). The blue color is gone

Observation	Hypothesis
Glucose + KOH + methyl blue if stirred continuously, the color of the solution will change from dark blue to light blue then become clear (blue is gone)	The blue color disappears from the reaction between glucose and KOH

4). Black foam

Observation	Hypothesis
Sugar + concentrated sulfuric acid after continuous homogeneous stirring of the color into solid black but no foam	The black color indicates the presence of carbon content

3). Heat

Observation	Hypothesis
Hypothesis Ethanol + aquades are mixed homogeneously, then the paper is dipped into the mixture	Then the resulting fire was burned blue but the paper did not burn. Alcohol has flammable properties. And water can not burn

1. Scientific Observations

a. Blue color disappears

            In this reaction the OH ion at KOH binds to H + derived from glucose. This neutrality produces water so that water causes the color in the solution to vanish. That's also because glucose is a neutral electrolyte in water, when reacting with KOH which is a strong electrolyte can make the color birru to disappear.

b. Black foam

            The ingredients used are sugar which is inserted into glass of cup 150 ml until half filled then added 15 ml of concentrated sulfuric acid, then stirred with caution. In this experiment not produced black foam, only black color is visible and this experiment is declared failed. What causes this experiment to fail is that the sugar is used too little and the sulfuric acid dosage is less precise. Theoretically can be written: C12 H22 O12 + H2SO4 12C + H2SO4 + 11 H2O.

c. Heat

            The material used is 40 ml of ethanol which is incorporated into 60 ml water, then dipped filter paper and placed in a watch and burned. At the time of being burnt, blue flames and filter paper are not burned. This proves that yng burn is ethanol, while the filter paper is not burned because it contains water. The resulting blue color is the flame color of ethanol.

5.1 CONCLUSION

From experiments on scientific observation and stoichiometry of the decomposition of KClO3 which has been done, it can be concluded that:

1. Praktikan can gain experience in recording, perform proper working procedures, explain experimental observations by using scientific observations to propose hypotheses using scientific methods and scientific experiments conducted.

2. In handling glass tools should be carefully, because the glass material can easily break. Therefore, thick glass materials such as test tubes of pyrex and in the experiment are used, when using a test tube should be placed in a staple brace. In producing chemicals can be done with caution. Solid chemicals must be dissolved in water first and if you want to mix one solution with another solution, pour it bit by bit