Using of Acid and Base to Remove Contaminants on Metal

A.      TITLE

Using of Acid and Base to Remove Contaminants on Metal

B.       OBJECTIVE

To know the most effective solution that can be used to remove contaminants on metal

C.      BASIC THEORY

An acid–base reaction is a chemical reaction that occurs between an acid and a base. Several concepts that provide alternative definitions for the reaction mechanisms involved and their application in solving related problems exist. Despite several differences in definitions, their importance becomes apparent as different methods of analysis when applied to acid–base reactions for gaseous or liquid species, or when acid or base character may be somewhat less apparent. The first of these scientific concepts of acids and bases was provided by the German chemist Antoine Lavoisier, circa 1776.

The first scientific concept of acids and bases was provided by Antoine Lavoisier circa 1776. Since Lavoisier’s knowledge of strong acids was mainly restricted to oxoacids, such as HNO3 (nitric acid) and H2SO4 (sulphuric acid), which tend to contain central atoms in high oxidation states surrounded by oxygen, and since he was not aware of the true composition of the hydrohalic acids (HF, HCl,HBr, and HI), he defined acids in terms of their containing oxygen, which in fact he named from Greek words meaning “acid-former” (from the Greek οξυς (oxys) meaning “acid” or “sharp” and γεινομαι (geinomai) meaning “engender”). The Lavoisier definition was held as absolute truth for over 30 years, until the 1810 article and subsequent lectures by Sir Humphry Davy in which he proved the lack of oxygen in H2S, H2Te, and the hydrohalic acids. However, Davy failed to develop a new theory, concluding that “acidity does not depend upon any particular elementary substance, but upon peculiar arrangement of various substances”. One notable modification of oxygen theory was provided by Berzelius, who stated that acids are oxides of nonmetals while bases are oxides of metals.

There are several methods of defining acids and bases. While these definitions don’t contradict each other, they do vary in how inclusive they are. None of the preceding theories is incorrect. Each succeeding theory includes that of its predecessors. What is true for the most specialized (Arrhenius theory) is also true for the most general (Lewis theory).

The Arrhenius theory defines an acid as any substance which produces H+ ions in solution, and a base as any substance which produces OH- in solution. The Bronsted-Lowry theory defines an acid in the same way the Arrhenius theory defines an acid (as a proton donor), but widens the definition of base to include any substance which will accept a free proton. The Lewis theory does not enlarge the Bronsted-Lowry theory of a base, although it shifts the emphasis from protons to electrons. The Lewis theory broadens the Bronsted-Lowry theory of acids to include any substance which can accept an electron pair. Therefore, according the Lewis theory, any elements or compounds which form compounds by coordinate-covalent bonding may be thought of as acids or bases. Consider the ammonia in the ammonia gas-water reaction.

NH3(g) + H2O(l)  NH4+(aq) + OH-(aq)

According to Arrhenius’ theory, ammonia is a base because it produces OH- ion when placed in water. The Bronsted-Lowry theory classifies ammonia as a base because it accepts a proton from H2O. The Lewis theory classifies NH3 as a base because it donates an electron-pair to a proton. What is considered an acid or base in the simplest theory is also considered an acid or base in the more complex theories.

Bacteria on Money. As we know, that the teller at a bank or office is the person who most often interact with money, especially paper money. In addition they are of course still many other individuals who interact with paper money, such as traders, mothers, housewives, school children who were given pocket money by their parents and so on. In short, because money is a means of payment in trade and economic transactions, then thousands and even millions of people certain to physically interact with paper money every day.

Bacteria can live and move easily around us. Displacement can be through various media, not least through the paper money. One type of bacteria or germs that are on the money is the cause of infections such as Staphylococcus germs that cause strep throat and pneumonia. To prove whether true on paper money there is a bacterial pathogen, then a student at Muhammadiyah University of Surakarta has conducted research on a sheet of paper money thousand dollars in the year 2007. The study concluded that indeed there are bacteria on a dollar banknotes circulating in the market Kleco Surakarta. The bacteria is bacterium E. coli is colored green and blue-black metallic.

In addition to paper money, coins or coin money also could be a means of spreading germs, but the amount is not as much on paper money. Paper money is the best medium for germs to move (transfer) from one person to another. Money is one item that is very dirty and full of different kinds of bacteria and microscopic insects. Dr. Darlington of the Health Commissioner of New York found about 135.000 bacteria on money especially banknotes.

Paper money can act as fomit potential as the media and transmitters causes a disease in humans if they are not careful in interacting and relating with it. Fomit are all inanimate objects associated with human or animal disease and potentially contain germs that can transmit the disease to other creatures. Paper money can become contaminated from the free air the dirty, dirty hands of men who held it or from places of storage of money that is not sterile.

Most of us feel that holding the money either paper or metal, will make our hands contaminated by many bacteria / viruses, but is that right? A study by Dr. Frank Vriesekoop, a researcher and a professor of food science at the University of Ballarat, Australia, reveal the facts behind the stories circulating in the community that the money is considered as one source of disease.

According Dr.Frank, it has been found several pathogenic bacteria on banknotes and coins, but …”… The potential spread of the disease is there, but I do not think that bad in reality “he said. He also stated that his team found the level of low antibiotic resistant bacteria on banknotes and coins. The results of the study appear in the annual conference of the Australian Institute of Food Science and Technology in Adelaide

The research team found a variety of organisms in coins and paper, including those that cause food poisoning or diarrhea. These include low levels of coliforms such as Escherichia coli bacteria, the bacteria are usually associated with colon and is generally associated with poor hygiene levels; and Staphylococcus aureus, a bacterium common in some strains of organisms that can cause disease in people who are vulnerable, and Bacillus Cereus , which cause food poisoning if not how to cook it to kill spores.

Effect of pH on bacterial

Microbes generally prefer a neutral pH (pH 7). Some bacteria can live at high pH (alkaline medium). An example is the nitrate bacteria, rhizobia, actinomycetes, and bacteria users urea. Only a few bacteria that are tolerant of acidity, such as Lactobacilli, Acetobacter, dan Sarcina ventriculi. Bacteria that are asidofil such as Thiobacillus. Fungi can live generally in the range of low pH. If microbes grown on medium with a pH of 5 is dominated by the growth of fungi, but when the media pH 8, it is dominated by the growth of bacteria. Based on the pH of microbes can be grouped into three namely

1.    Microbial asidophyll, are a group of microbes that can live at pH 2.0 to 5.0

2.   Microbial mesophyll (neutrophils), is a group of microbes that can live at pH 5.5 to 8.0, and

3.   Microbial alkaliphyll, are a group of microbes that can live at pH 8.4 to 9.5.

D.      HYPOTHESIS

Strong acid and base will remove contaminants on metal faster than weak acid and bas

 E. TOOL AND MATERIAL

Tools                                                               Materials

  1. Coin                                                                        1.   NaOH(s)
  2. Erlenmeyer flask                                                 2.  CH3COOH(l)
  3. Beaker glass                                                         3.  HCl(l)
  4. Three beam balance                                           4.  Distilled water

F.    PROCEDURE

  1. Preparing 20 ml NaOH, CH3COOH, and HCl solution by dilution to concentration
  2. Pouring each solution to three beaker glass
  3. Pouring distilled water in to another beaker glass
  4. Soaking a coin in each beaker glass for 30 minutes
  5. Observing the change of each coin and solution in those beaker glass every 15 minutes

G.      EXPLANATION

Experiments on the use of acids and bases to remove metal contaminants at present we do in the day Thursday, November 3rd, 2011 at the Laboratory Science 2 Faculty UNY. This experiment aims to determine the most effective solution to remove contaminants on the metal. In this experiment, we used three variables (independent variables, control variables and the dependent variable). The independent variable of this experiment is the kind of solution. In this case we use four types of solutions, namely NaOH, CH3COOH, HCl, and distilled water. For the control variable is the volume of solution (20 ml), concentration of the solution (2M), long soaking (30 minutes), the number of coins (1 per cup kmimia), and the last one we tried to use a coin with the same gross rate. The last variable is the dependent variable. Dependent variable of this experiment is a state of solution and coins after 30 minutes.

We can find three aspects of the IPA in this experiment. The third aspect is the aspect of chemistry, physics, and biology. There are several aspects of chemistry in this experiment. The first is about the dilution was made to make a solution of NaOH, CH3COOH, and the concentration of 2M HCl. Create a solution with a concentration of 2M is by dilution. Dilution is a homogeneous mixing between the solute and solvent in the solution. On dilution of acetic acid we use because it requires measuring flask and 100 ml volume of acetic acid required is 11.5 ml. Was obtained from calculations with the formula, namely

Mol CH3COOH 100% = (100 X 1.05 X 1000) / 60

Obtained mol = 17.5

V1 x V2 x M1 = M2

100 x 2 = V2 x 17.5

V2 = 11.5 ml

Then pour a solution of acetic acid with a total of 11.5 ml volume pipette into the flask and add distilled water to the limit of 100 ml in volumetric flask. And we only need 20 ml of acetic acid.

The second we make a solution of 20 ml of 2M NaOH. Previously we considered necessary in NaOH 2M dilution volume of 20 ml. Determine its mass by calculating the following formula

M = (g / MR) / V

2 = (gr/40) / 0.02

2 = gr / 0.08

Mass = 1.6 g

After we calculate the weigh NaOH as required and then dissolve it with as many as 20 ml distilled water in glass beaker.

Dilution of the HCl 2 M. The third Steps taken together with the first step is to find the volume of HCl required to use the formula. Volume of HCl required is 3.4 ml distilled water and used as much as 20 to 3.4 = 16.6 ml. Due to the volume of solution required only 20 ml so we do not need to use a volumetric flask so that we only use a pipette to measure the volume of solution required.

The second is the chemical aspects of chemical decontamination. Decontamination of getting rid of all the visible material (dust, dirt) on the object, the environment, the skin surface using a particular material. Decontamination process whose objective, among others: the first takes the contaminants on the surface of materials can take place quickly if the presence of surface contaminants just stick out and be different if its existence is in the pores of the material, preventing the spread of infection via equipment or environmental surfaces, the second to remove dirt that looked, to remove impurities that are not visible (microorganisms), and so forth. Therefore it is necessary to the erosion of material equipment, so that the contaminants will be separated with the particles entrained pengikisannya results.

There are several kinds of decontamination, one of which is a chemical decontamination methods. This method is used to eliminate / reduce the contamination on the surface of metal or other materials by a chemical process. Chemical decontamination methods can be by using a high concentration or low concentration. Called when a high concentration of chemicals used in more than 1%, while the so-called low concentration if the chemical is used less. In this method, usually accompanied by heating or stirring / circulation for decontamination of equipment, appliances or systems at nuclear facilities at a certain age will experience contamination that occurs due to contact with radioactive substances or activated. For materials made of metal, its contamination layer called the crud. In accordance with the chemical composition of metal-contaminated, then the composition of the crud is also composed of the constituent metal oxides, for example for aluminum metal. Here is the money used aluminum metal. The coin is made of hardened aluminum. Until now, hard to find what material alloy coin money maker this silvery white, chances are withheld to prevent the counterfeiting of coins.

At pH 5 the room temperature CH_3COOH sufficient decontamination factor affecting the acquisition value. This is expected, since the pH is based on the reduction mechanism of decontamination Al ^ (3 +) into Al ^ (2 +) by acetic acid and sodium hydroxide, hydrochloric acid in this condition is only likely to function as an acid, rather than as an oxidant. In the hydrochloric acid showed no increase in the value of the decontamination factor. Dissolution of the oxide layer and the erosion of the base metal surface causes fewer contaminants also removed. In the atmosphere of an alkaline pH, Al ^ (3 +) does not stick back on the metal surface, because this Al ^ (3 +) form of soluble salts in solution. Hydrochloric acid does not show the value added at factor significant decontamination. At pH conditions of the above properties reductant acetic acid and sodium hydroxide is thought to be reduced and complexing compounds. decontamination factor of this study is the largest of NaOH at pH 14, the concentration of 2M sodium hydroxide. Decontamination factor in the realization of the value can still be enlarged, probably by raising the temperature and time and increase the levels of alkaline solution used in the decontamination process. At pH akudes shown is 6. From the data mengnai pH data taken after the coin is inserted into the solution and their reaction dintara. Since it was terkontasi the pH no longer fit properly. Contribution of pH on the experimental variables is also positive because the increase in pH would facilitate the formation of hydroxyl ions and elevates the conductivity of the solution, so that the interaction between aluminum and the solution will increase. Contribution of time is related to the amount of metal cations, it is in accordance with the faraday law where the amount of metal cation formed is directly proportional to time. The longer the time spent, the more metal cations are formed and the more chances of interaction of metal with a solution.

Aspects of the physics of this experiment are in manufacturing activity 2M NaOH solution of NaOH (s). To make the solution, we must weigh the NaOH (s) in accordance with the calculations have been performed. Weighing is done by using a three-arm balance. Balance of the three arms of a traditional balance sheet modified to obtain a higher degree of accuracy. In the three-arm balance, there are three arms, each of which has been hung with objects that have different masses. In the first arm of the scale there are between 0g – 200g to 100g the smallest scale, in both arms there were scales between 0g – 100g with 10g smallest scale and scale of recent arm 0g – 10g with the smallest scale of 0.1 g. By knowing the smallest scales in the balance sheet contained three arms, we also can know that the level of accuracy of three-arm balance is 0.1 g.

The working principle of this balance is simply comparing the mass of the object to be dikur with weights. Weight balance of the three arms are on the balance sheet itself. Measurement capabilities of this balance can be changed by shifting the position of the weights along the arms. Weights can be moved away or close to the balance shaft. Mass of the object can be determined from the sum of each weight along the arm position after the balance sheet in a state of equilibrium. Others say the principle of mass as the working principle of the lever.

The parts of the balance of the three arms is where the load is used to place the object to be measured, the calibration is used to calibrate the balance sheet when the sheet can not be used to measure, three arm balance to balance arm means that there are three arms, ballast (earrings) are placed on each sleeve that slides and a pointer-shear measurements, the point 0 or the line of equilibrium, which is used to determine the equilibrium point.

How to read the results of measurements of the mass of the balance sheet are as follows:

Read the position of the arm back earrings

Read the position of the middle ear on arm

Read the position of earrings on the front arm

Pegukuran results with the three arms of the balance sheet is by summing the results shown by the three arms.

Biological aspects in this experiment is about the possible contaminants that exist on the coins. We know that the money in the form of notes and coins is a common thing, held, and used in everyday life as a medium of exchange. From the description it could be concluded that the money was a potential breeding sites of microbes, especially bacteria. Bacteria can live and move easily around us. Displacement can be through various media, not least through the money. Both the currency notes and coins could also be a spreader of germs, but there were not as much on paper money. One type of bacteria or germs that are on the money are the germs that cause Staphylococcus infections such as strep throat and pneumonia. Even the study Dr. Darlington of the Health Commissioner of New York found about 135. 000 bacteria on the money.

In some other articles about the research also shows that the team found a variety of organisms in a coin and paper, including those that cause food poisoning or diarrhea. These include low levels of coliforms such as Escherichia coli bacteria, the bacteria are usually associated with the colon and is generally associated with poor hygiene levels; and Staphylococcus aureus, a bacterium common in some strains of organisms that can cause disease in people who are vulnerable, and Bacillus Cereus , which cause food poisoning if not how to cook it to kill the spores.

At trial the use of acids and bases to remove the metal dekontaminan by praktikan, praktikan provide results from the effects of metal immersion in weak acid solutions, strong acids, strong bases, and distilled water using only the turbidity level of the indicator solution as well as the cleanliness of aluminum metal without observations in more depth in the metal that has been given such treatment. In the strongly acid solution showed that the contaminants or impurities from detached and floated on the surface of the solution, and the solution is cloudy. In the strongly alkaline solution of the chemical reaction between the solution to the metal. In the weak acid is not too show the influence of contaminants on the coins. At precisely distilled water showed no change either in distilled water tersebut.selain in solution, the observation of the contaminants also performed on the coin. On coins soaked in strong acid HCl showed that the net result or level of cleanliness can be said net + + +, the coins are immersed in a strong base NaOH showed that some contaminants have been released and coins into the net with the cleanliness of clean + + + + + , the coins are immersed in a weak acid CH3COOH sedikitt results show that the coin is cleaner than the initial state with the cleanliness of clean + +, while the coins are immersed in distilled water showed no change in the cleanliness of the coin and the coin is still mengandiung contaminants on the surface.

Based on the literature, pH can affect the bacteria. Microbes generally prefer a neutral pH (pH 7). Some bacteria can live at high pH (alkaline medium). An example is the nitrate bacteria, rhizobia, actinomycetes, and bacteria users urea. Only a few bacteria that are tolerant of acidity, such as Lactobacilli, Acetobacter, Sarcina ventriculi and. Bacteria such as Thiobacillus asidofil nature.

Based on the pH of microbes can be grouped into three namely:

Asidofil microbes, are a group of microbes that can live at pH 2.0 to 5.0

Mesophyll microbe (neutrophils), is a group of microbes that can live at pH 5.5 to 8.0, and

Alkalifil microbes, are a group of microbes that can live at pH 8.4 to 9.5.

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