Is the pH always related to protons

Acids in the pantry (sec

Acids in the pantry Acids in the pantry H + A lesson based on chemistry in context -1- Acids in the pantry Structure of the lesson Std Grading of the lesson Context-related student activities Main intention 1 Encounter & amp; Structuring phase Working with picture cards, collecting and categorizing questions Gathering everyday ideas about acids What are acids? - AB to introduce "the biologists" of sour taste as well as "the chemists" of acid molecules measurement of differently acidic foods with the help of pH measurements as a substitute for the taste test (experiment) development and execution of an experiment, which shows whether and in what way cola harms the teeth. Elaboration of the acidic term according to Br & ouml; nstedt (H + donor) Introduction of the pH value as a measure for the proton conc. Competence development in the field of knowledge acquisition. Competence development in the field of assessment. Context-related development of a protolysis reaction. see lesson 4 2 3 4 HA research: How does tooth decay develop? 5 HA elaboration phase 6/7 Evaluation of the experiment, elaboration of the development of caries when exposed to cola (AB). Written evaluation of the experiment What is the gastric acid used for? Info sheet (germicidal effect of acids, enzymes, pH-dependency of enzyme activity) as well as development and implementation of an experiment on protein digestion. Test evaluation; 8 AB on donor-acceptor concept HA processing of AB 9 Combating heartburn with Aludrox (attempt to neutralize) HA info text: How does milk get sour? (Lactic acid bacteria, coagulation of milk) 10 11 13 HA 14 Advanced phase Development and implementation of an experiment for the production of yoghurt Evaluation of the yoghurt experiment Reference to the structuring phase; Glossary for securing technical terms; How does Helicobacter survive in gastric juice? (Demonstration experiment) Evaluation of the demonstration experiment Vitamin C - the life-sustaining acid. Experiment and derivation of nutrition tips -2- Application-related development of the effect of acids on proteins and enzymes. Competence development in the field of knowledge acquisition; development of a basic concept. Application of the DA concept to examples Application-related development of neutralization. Application of knowledge about denaturing skills development in the field of knowledge acquisition see lesson 11 Horizontal networking of student knowledge; Application of knowledge about protolysis see lesson 13 Competence development in the area of ​​knowledge acquisition and evaluation -3- Acids in the pantry What are acids? Biologists' presentation of the sour taste The sour taste is due to the presence of protons (H +) and serves on the one hand to stimulate the appetite, but on the other hand also to warn of spoiled food. Ion channels in the taste cells of the tongue serve as detectors for the protons. Changed from: Stephan Frings, University of Heidelberg, Department of Molecular Physiology, June 2003 Introduction of the chemists of acid molecules → hydrochloric acid → carbonic acid Complete the reaction schemes and discuss with your neighbor what an acid should be. ure indicates: -4- Acids in the pantry Why do some foods taste more sour than others? 1. Taste test Works in groups of 4 and dilutes lemon juice concentrate in a ratio of 1:10, 1: 100 and 1: 1000. For measuring, you will be provided with shot glasses (20 ml) and water glasses (200 ml) made of plastic. Try the prepared solutions with the straw. Discuss the reliability of our tongue as a measuring instrument! Here is an explanation of your different taste sensations: 2. pH measurement Following this experiment, you should get to know pH sticks and digital pH meters as a tool used by chemists to determine the concentration of protons in a solution. First of all, the solutions you have mixed will be used. Result: Universal indicator: pH meter: conc .: 1.5 conc .: 1.9 1:10: 3 1:10: 3 1: 100: 1: 100: 1: 1000: 41: 1000: 4.1 The pH - Value is an abbreviation for "potentia hydrogenii" (= the power of hydrogen). It can have values ​​between 0 and 14. The lower the pH, the higher the concentration of protons. Determines further pH values ​​of liquids from the pantry: -5- Acids in the pantry Do acidic foods damage your teeth? Works in groups of four. Imagine that you are a research team tasked with answering the question mentioned above. In your final examination report, you should later describe in as much detail as possible what may have (not) changed on tooth 1. Before you start it, think about exactly how you want to carry out your experiment in order to be able to draw as many conclusions as possible from it later! 1. Write down here as precisely as possible how you want to proceed! 2. Clarify your plan with the teacher before you start! 3. Make a note of the results in the before and after comparison! Criterion Before After 4. Now write a summary answer to the question of whether acidic foods harm your teeth! 1 Chicken bones are available to replace real teeth. They essentially consist of the same substance (hydroxyapatite) as teeth. -6- Acids in the pantry Skirting foil: -7- Acids in the pantry Do acidic foods damage your teeth? (Evaluation) Before you look at the result of your experiment from the last lesson, you should first “warm up” chemically so that you can also make a hypothesis for possible damage to the teeth in this regard. nnt. 1. What kind of acid is in the cola? It is phosphoric acid. Please complete the reaction scheme: → Phosphoric acid + phosphate 2. What substance is a tooth made of? What you see on the outside of the tooth in healthy teeth is the tooth enamel, which covers the dentin like a crown. Tooth enamel is the hardest substance in the human body. It consists of 95 percent hydroxyapatite ([Ca5 (PO4) 3] OH), a salt-like compound that consists of calcium cations (Ca2 +), phosphate anions (PO43-) and hydroxide anions (OH-). These three ions are arranged in a very regular ion lattice in tooth enamel. Draw the two anions in the hydroxyapatite in the LEWIS notation: Phosphate ion (PO43-) Hydroxide ion (OH-) 3. What can happen if Cola has a permanent effect on a tooth? -8- Proton Acids in the Larder Now think about which of the ions in the hydroxyapatite could react with the protons from the cola to form a product that you know well! Write down the reaction scheme here: What consequences would it have for the stability of the tooth enamel, should this reaction actually take place? 4. Additional task: Many toothpastes contain fluoride ions. You can "harden" the enamel. This means that they replace the hydroxide ions in the tooth enamel close to the surface. This creates the less acid-sensitive fluoroapatite. Complete the reaction scheme for this process! [Ca5 (PO4) 3] OH + F hydroxyapatite → + + fluoride fluorapatite + reasons why you should brush your teeth for at least 3 minutes: -9- Acids in the pantry What is the gastric acid used for? (Information) One can only answer this question to oneself (and others) if one has previously obtained information about a vital group of substances, the proteins. Proteins are vital for plants and animals in two respects: First, every living being consists of a significant proportion of proteins (muscle meat, for example, over 20%). Since we humans cannot produce this "building material" ourselves, we have to ingest proteins that are foreign to the body through our food, which are broken down in the course of digestion and then converted into new, human proteins. The digestion of proteins occurs in the stomach. Second, there is a special group of proteins that does not serve as a building material, but keeps the entire metabolism in a plant or animal organism going: the enzymes. Without enzymes, all life processes in our body (breathing, movement, brain activity, digestion, ...) would immediately come to a standstill. A different enzyme is “responsible” for each of these processes. To name three examples from the area of ​​digestion: The enzyme amylase helps to break down carbohydrates in the mouth, the enzyme pepsin in the stomach to break down proteins and the enzyme arginase to break down protein building blocks in the liver. Regardless of whether a protein is used as a building material or as an enzyme - all proteins have one thing in common: They are very sensitive to fluctuations in temperature and pH value. If the limit values ​​(which are different for each protein) are exceeded or undershot, irreversible (irreversible) damage to the protein occurs, which is also known as denaturation (coagulation). A denatured protein can no longer perform its tasks in the body. Tasks: 1. Why does a person die when his body temperature rises above 42.6 ° C? 2. Why can you protect food from decay (= bacterial contamination) if you cook it or “pickle it”? - 10 - Acids in the pantry 3. Describe the content of the diagram. 4. On the basis of exercise 3.) give another argument why a permanently low pH value in the oral cavity is harmful! - 11 - Acids in the pantry What is gastric acid used for? (Experiment) On the basis of the preliminary information that you have received, you should now - as already on the question of "acids in the mouth" - design your own experiment. This time, please remember to discuss your concept with the teacher before you start implementing it! Work assignment (groups of 4): Your experiment should clarify the question of the importance of gastric acid in digestion in the stomach. Chicken meat should be used as digestible food. Equipment: water bath (37 ° C), 4 test tubes, RG rods, foil pen, pipettes, chemicals: chicken, gastric acid solution (= hydrochloric acid), pepsin solution solution, water Test approach / observations: Chicken Meat Gastric acid Pepsin Water RG 1 x RG 2 x RG 3 x RG 4 x Description beforehand Description after 5 minutes Description after 3 days in a water bath Evaluation: 1. Make detailed assessments of what with this attempt could be shown. 2. Name further questions that you would like to clarify on this topic. 3. Sketch out an experiment that you would use to investigate one of these questions. - 12 - Acids in the pantry The donor-acceptor principle Now that the first half of the teaching unit "Acids in the pantry" is over, you should take a look back today and discover this new group of substances " Classify acids ”against the background of your knowledge of redox reactions. To do this, refresh your memory of redox reactions by completing the following reaction scheme: Sodium reacts with chlorine: Ox .:  Redox .:  Redox:  A redox reaction only takes place if both one Oxidation as well as a reduction can take place. The sodium atom only gives up its electron when a chlorine atom is nearby to take it up! The same applies to the chemical behavior of the acid molecules, but this time related to the protons: Acids only split off their proton (s) if another molecule (the so-called Base) is close to pick it up. The acid reactions you have formulated so far are only one of two partial reactions - the second partial reaction, that of the base, was still missing. The resulting overall reaction is called an acid-base reaction or protolysis reaction: Donor (acid):  Acceptor (base):  Protolysis:  In most cases - as here - water reacts as a base with the acid and absorbs the proton. This creates an oxonium ion (H3O +). Understand everything? You can find exercises on the back! Definitions: Redox reaction Reaction in which …………………… .. are exchanged. Protolysis reaction Reaction in which …………………… .. are exchanged. Acid proton donor. Molecule that can ……………………………… protons (hydrogen cations). Base proton acceptor. Molecule that can ……………………………… protons (hydrogen cations). - 13 - Acids in the pantry Formulate the protolysis reactions (without partial reactions) for the three acids that you have already encountered in the course of this unit: hydrogen chloride, carbonic acid and phosphoric acid. Let them each react with water. If the acid emits several protons, correspondingly more water molecules react! Hydrogen chloride: carbonic acid: phosphoric acid: The solutions that arise during these reactions are all rich in oxonium ions. Such solutions are called acidic solutions. - 14 - Acids in the pantry Combating heartburn with Aludrox Almost half of the German population suffers regularly ; ig from heartburn. Various causes (e.g. excessive consumption of acidic foods and drinks) cause gastric juice to flow back into the esophagus (Fig. 1). In contrast to the stomach, the esophagus is not protected by a mucous membrane against the rising acidic solution ("gastric acid"), so that it is attacked by it. The salt aluminum hydroxide (Al (OH) 3) is the most common ingredient in so-called "antacids", ie drugs such as Aludrox®, which are supposed to alleviate heartburn. When chewing Aludrox tablets, the aluminum hydroxide dissolves as aluminum cations (Al3 +) and hydroxide ions (OH-). A solution that contains hydroxide ions is called an alkaline solution. 1. Consideration Draw a hydroxide ion and understand how this particle might be able to relieve heartburn. Put your hypothesis into a reaction scheme! - 15 - Acids in the pantry 2nd model experiment Now carry out the following experiment in order to transfer the processes involved in taking an Aludrox chewable tablet to the laboratory. Because it dissolves better in water, we replace the aluminum hydroxide with a sodium hydroxide (NaOH) tablet (caution: corrosive!). Clarification: Read the experiment instructions through and make a note of the areas in the human body for which the three test tubes should be: Test tube 1: ________________________________ Test tube 2: ________________________________ Test tube 3: ________________________________ Devices: Test tubes, 3 test tubes for chemicals: hydrochloric acid solution, 1 tablet of sodium hydroxide, water, universal indicator, protective goggles Procedure:  Put a thumb's breadth into the first test tube and add hydrochloric acid 1-2 solution Add drops of the indicator solution.  In the second RG you dissolve a tablet of sodium hydroxide (corresponding to Aludrox®) in 1 DB of water and also add 1-2 drops of indicator solution.  Now put half of the solution from test tube 1 into the 3rd test tube. Then you add a little of the solution from test tube 2 with the pipette until you see a change in the observe the pH value. Note! Repeat the experiment with the remaining solutions from test tubes 1 + 2 to confirm your observations. Observation: Interpretation against the background of the hypothesis formulated above: - 16 - Acids in the pantry How does milk become sour? Milk is actually sterile - at least as long as it is in the udder. But skin bacteria get into the milk as soon as they pass through the teat. And dead body cells. They are not dangerous to health, but if their number gets too high, it can be an indication of an udder infection. Once the milk is out of the cow, other bacteria join in. Milk spoilers and pathogens Milk spoilers are responsible for the fact that milk goes bad if you give them the opportunity to reproduce.Depending on where the cow lives and what it gets to eat, the make-up of the milk spoilers varies. In the past, these were mainly lactic acid bacteria, such as B. Lactococcus lactis: They make the milk sour, and that is undesirable with drinking milk. The lactic acid bacteria process the milk sugar into lactic acid, which in turn precipitates the milk protein - mainly casein: the milk coagulates (denatures). Whoever put fresh cow's milk on the window sill early in the evening to have curdled milk the next day made a virtue out of necessity and used this effect. Today the simple "window sill method" no longer works. The reason: Today, the dairy cows are mostly in the barn instead of on the pasture and eat concentrated feed instead of grass. As a result, their bacterial flora has also changed: Today's milk spoilers mostly form acetic or propionic acid and other metabolic products that make milk inedible. The pathogens that can appear in milk include, for example, salmonella, B-streptococci or certain strains of the intestinal bacteria Escherichia coli, which cause violent rashes and abdominal cramps. Fortunately, pathogens in milk are rare, and if they are discovered there, the milk is immediately withdrawn from circulation. Tricks of the bacterial police Immediately after milking the milk is cooled to 4 ° C, which inhibits the growth of bacteria. At the same time, their number is determined: if it is too high, the milk must not be processed further. Raw and preferred milk are particularly strictly controlled here: Because these types of milk are sold completely untreated, whatever bacteria are in them remains in them. With all other types of drinking milk, milk dwellers are put on the body with heat. Pasteurization is the most gentle for the vitamins and proteins in milk: heating to 72 to 75 ° C for 15 to 30 seconds. Above all, the pathogens are killed. The milk spoilers also have to believe in it, but not completely. Pasteurized milk - the drinking milk from the cooling shelf, for example - is therefore only chilled and can only be kept for a few days. With ultra high temperature heating, the milk is heated to 135 to 150 ° C for a few seconds. All bacteria capable of reproduction are killed, but some of the heat-sensitive B vitamins are also destroyed and protein building blocks are changed. The result is so-called long-life milk, which can be kept for several weeks if unopened. Sterilized milk is heated to 110 ° C for about 10 minutes in the closed package. It no longer contains any living germs and can be kept unopened for up to a year. For this, however, it has also incorporated most of its vitamins and its proteins have been greatly changed. - 17 - Acids in the pantry Lactic acid bacteria in industrial use If you don't just want to drink milk, but also want to make other dairy products from it, you have to rethink bacteria: Annoying germs become indispensable helpers without them Do not use yogurt, sour milk or cheese. However, you use very specific strains of lactic acid bacteria for this, which you add specifically and under controlled conditions to the milk, depending on which milk product you want to have. In principle, they all do the same thing: They convert the milk sugar into lactic acid and thus allow the milk to curdle. But the strains have different pH optima and form different aromas: To produce sour milk, crème fraiche and sour cream, mainly so-called mesophilic lactic acid bacteria are used. They don't like it too warm, around 20 ° C, and produce a relatively mild aroma. This type of lactic acid includes, for example, strains such as Lactococcus lactis or Lactococcus cremoris. Yoghurt is produced by thermophilic - i.e. warmth-loving - lactic acid bacteria that like it a little bit more acidic and warmer, around 40 ° C. Lactobacillus bulgaricus, the Bulgarian yoghurt bacterium, produces a relatively sour, tart taste. In Germany, the so-called “mild yoghurt” is more popular. For this purpose, strains of bacteria are used that do not acidify as strongly as e.g. B. Lactobacillus acidophilus and Bifidobacterium bifidum. What many do not know: The living bacteria are still contained in finished dairy products such as yogurt and sour milk - we eat them with us. For the most part, they are killed off by the acidic pH in our stomach. Source: Quarks & amp; Co, WDR Fernsehen Tasks: 1. Fresh cow's milk changes when you put it in a warm place. What happens? 2. What does it take to make yogurt yourself? 3. How can you prevent undesired or dangerous bacterial strains from multiplying? - 18 - Acids in the pantry Test protocol: Production of yoghurt Describes once again briefly what happens when liquid milk becomes solid yoghurt: Now it's about the experiment. Name the questions that you want to clarify and describe your experimental approach! What exactly goes into which of the three test tubes? Continue on the back! Record the result of the experiment there as completely as possible! - 19 - Acids in the pantry Were you able to answer all of your questions? If not, make changes to get better results! - 20 - Acids in the pantry How does Helicobacter survive in gastric juice? As you learned in the previous unit, the gastric juice of humans is strongly acidic. In this environment, all bacteria that get into the body with food usually die in a very short time - all but one: Helicobacter pylori survives and can cause dangerous diseases of gastric mucosal inflammation (inflammation of the gastric mucosa). Gastritis) up to stomach cancer. But how does the bacterium manage to survive in the acidic solution of the stomach? Note: The bacterium is able to produce a gas - ammonia. Ammonia has the following molecular formula: In order to familiarize you with the properties of this gas, a model experiment will now be performed: In a glass tub there is an acidic solution that corresponds to gastric juice. Small pieces of foam, which represent the ammonia-producing Helicobacter bacteria, are placed in this solution. Helicobacter gastric juice Note: The foam pieces are prepared with ammonia water. In the solution there is a universal indicator. Exercises: 1. Draw the indicator colors in the picture! 2. Interpret the indicator colors with the help of reaction schemes! 3. Use the model experiment to explain why Helicobacter can survive in gastric juice! Use the back for your answers! - 21 - Acids in the pantry James Lind discovers a life-sustaining acid James Lind (1716-1794) The disease scurvy was previously notorious among seafarers. The first symptoms are severe fatigue, bleeding gums and increased susceptibility to infectious diseases. In the further course, joint inflammation and muscle wasting occur. A heart failure ultimately leads to death. For a long time the disease was considered incurable, until the English ship's doctor James Lind proved in 1752 that the preventive intake of lemon juice prevents scurvy. Today white It is clear that lemons mainly contain two active ingredients in higher concentrations: citric acid and ascorbic acid. Try to find out which of the two acids is responsible for the life-sustaining effect of lemon juice! The "turning brown" of grated apples serves as a model for the physical deterioration of scurvy sufferers. Lemon or ascorbic acid are available for "treatment". Both are solids that dissolve well in water. First describe the planned implementation before you start the experiment! Implementation: Observation: Interpretation: - 22 - Acids in the pantry Vitamin C Vitamins are substances that animals (including humans) cannot and cannot produce independently from other nutrients therefore have to be added continuously with the food. The daily requirement for a vitamin is usually a few milligrams, i.e. a few crystals of the substance. If a person takes in more vitamins than necessary, the "excess" is excreted with the urine. Ascorbic acid is also known as vitamin C. It protects the body from many diseases, some even claim from cancer. The strengthening of the immune system against flu viruses by vitamin C is undisputed. The recommended daily dose of this vitamin is 100 mg. Vitamin C content of selected products (per 100g) Food content Food content Black currants 189 mg tomatoes 24 mg parsley 166 mg sauerkraut 20 mg strawberries 62 mg lettuce 10 mg lemons 53 mg apples 4 mg oranges 50 mg cow's milk 1.6 mg potatoes 28 mg cheese 1 mg vitamin C - loss depending on the type of preparation compared to raw food preparation method cooking in steam cooking in water freeze drying heat treatment before canning air drying loss 16 - 26% 16 - 58% 43% 48% 50 - 70% Tasks: 1. Think about whether you have already covered your daily vitamin C requirement today! 2. Rate “hot lemon” and “hot elderberry juice” as flu medicine! 3. Formulate a general dietary rule on the basis of the two tables: - 23 - Acids in the pantry lexicon on the basic terms of the teaching unit Donor-Acceptor principle Protolysis Acid base Acid solution Alkaline solution ("Lye") Neutral solution Neutralization pH value pH meter indicator apatite Basic principle in chemistry, according to which electrons (redox reactions) or protons (protolysis reactions) can only be given off if they are absorbed by another substance. Free, unbound electrons or protons are therefore always present only temporarily. Reaction in which protons (hydrogen cations, H +) are exchanged. Proton donor. Molecular compound whose molecules are able to split off protons in the presence of a base. Proton acceptor. Molecular compound whose molecules are able to take up protons in the presence of an acid. Solution with increased content of oxonium ions (H3O +) and low content of hydroxide ions (OH-). The pH of an acidic solution is 0-6.9. It typically arises from the reaction of an acid with water. Solution with increased content of hydroxide ions (OH-) and low content of oxonium ions (H3O +). The pH of an alkaline solution is 7.1-14. It typically arises from the reaction of a base with water. Solution with a balanced, low content of hydroxide and oxonium ions. The pH value of a neutral solution is 7. It consists mainly of water. Reaction in which the pH value of a solution is shifted from acidic or alkaline to the neutral range (pH 7). This creates water. Abbreviation "potentia Hydrogenii" (The power of hydrogen). The pH value tells you how high the concentration of oxonium ions is in a solution. In other words: it says whether an acidic, neutral or alkaline solution is present. Electronic measuring device for determining the pH value. Available as a liquid solution or applied to strips of paper. Contains a mixture of dyes that reacts to a change in pH with a "color change". The pH value can therefore be determined on the basis of the color that occurs. The ionic compound (salt) that our tooth enamel is made of. It contains calcium (Ca2 +) ions as well as phosphate (PO43 -) and hydroxide (OH -) ions. When tooth decay develops, the enamel is softened because the hydroxide ions react with protons to form water molecules. When brushing your teeth, the hydroxide ions are exchanged for fluoride (F) ions, which are insensitive to protons. - 24 - Acids in the pantry Proteins Heartburn Bacteria Proteins. An indispensable group of substances in every living organism, which can be roughly divided into building materials and enzymes. Proteins are characterized by the fact that they are sensitive to changes in pH and temperature. Beyond a border area, they denature, i.e. they change their structure irreversibly and can then no longer perform their respective function. This denaturation (“coagulation”) of proteins can often be seen with the naked eye (e.g. boiling eggs, flocculent milk, frying meat). Term for the rising ("reflux") of acidic solution from the stomach into the esophagus. The unpleasant, burning feeling can be eliminated by taking an alkaline solution (neutralization). Single-celled living beings that take on a variety of tasks in nature's cycle of materials. One of these tasks is the breakdown (decomposition) of substances. In this regard, they play an important role in the human intestine ("intestinal flora"). Some types of bacteria break down sugar into acids (e.g. lactic acid bacteria, acetic acid bacteria). - 25 - Acids in the pantry Notes on the networking phase The aim of the networking phase is to take up technical content from the development phase in a new context. The acid rain context proposed here is suitable because it “broadens the horizon” to a certain extent (from the domestic environment to the global problem, from responsibility for one's own health to responsibility for the environment). In principle, however, any other context in which acid-base reactions play a central role would also be suitable. Didactic tips: - The carbonate weathering by acid rain is deliberately left out in the present material because it assumes the concept of chemical equilibrium. Here, first - in analogy to other acids - the formation of carbonic acid from carbon dioxide and water is considered. - Some reactions in this phase may represent a new type of reaction for the students, which initially does not seem to have anything to do with redox or protolysis reactions. Whether the introduction of oxidation numbers is necessary here is at the discretion of the teacher. - 26 - Acids in the pantry Acid rain Look at the following picture and write down questions that you would like to clarify in class! My questions: - 27 - Acids in the pantry Under what circumstances do acidic solutions damage plants? It is your job over the next week to find an answer to the above question. For this you carry out a long-term experiment, which you should record as precisely as possible (photos)! Since you work at home, you can use household vinegar as an acidic solution, which you can dilute as needed. In your final investigation report, you should later describe in as much detail as possible what may have (not) changed in your plants. Now think about which research question (s) 2 interest you and how you have to set up your experiment in order to answer these questions as reliably as possible: Subsequently, present the plan to your teacher! 2 The following sample questions can serve as a suggestion:     Which acid concentration can be endured permanently, at which point does the plant die? Is spraying the leaves with acidic solution (rain!) Just as harmful as watering them? Do different plant species react differently to acidic solutions? What role do different soils play in the sensitivity of plants? - 28 - Acids in the pantry What effects do car exhaust fumes have on the atmosphere? During a trip of 100 km, a car consumes approx. 12960 l (or 12.96 m3) of oxygen and approx. 8 liters of gasoline! The following gases are released: Proportion (%) Volume (l) CO2 87.6 7422.3 CO 10.3 872.7 NxOy 0.6 50.8 SO2 0.06 5.1 Remainder 1.47 124.6 Total 100 8,475.5 But what happens now when these exhaust gases get into the atmosphere? To measure this, first carry out the following experiment in groups: Equipment: Piston sampler with tap, tube (10 cm), 3 Erlenmeyer flasks (100 ml), pH meter, spray water bottle Procedure: 1) Pour 100 ml of water into the beaker and note the pH value 2) Place the tube on the gas syringe and take an exhaust gas sample of 200 ml from the exhaust of a running car engine.3) Slowly press the exhaust gas into the water sample 4) Now determine the pH value again and note the difference 5) Repeat the experiment three times with fresh water to ensure your result Observation: Task: Calculate how many liters of rainwater you have With the amount of exhaust gas from a 100 km trip, the pH difference you determined could "acidify"! - 29 - Acids in the pantry How do you turn car exhaust fumes into acid rain? 1. When a mixture of substances containing carbon, sulfur or nitrogen is burned, the oxides of these elements are released as gases: a) LEWIS formula:   Molecular formula:   Word equation: _____________________________________________________ b) LEWIS formula:   Molecular formula:   Word equation: _____________________________________________________ c) LEWIS formula:   Sum formula:   Word equation: _____________________________________________________ 2. These gases react in the clouds with water to form acids: a) LEWIS formula:   Sum formula:   Word equation: _____________________________________________________ b) LEWIS formula:   Sum formula:   Word equation: _____________________________________________________  c) LEWIS formula: Sum formula: 4 NO2   2 H2O   O2  4 HNO3 Word equation: _____________________________________________________ - 30 - S & auml; urs in the pantry 3. When these acids react with more water, they then form Ultimately acidic solutions. When setting up the reaction schemes, follow the same pattern as on the front page! Two reaction steps are to be specified for two of the acids: a) b) c) In general: "Acid rain" is due to the fact that non-metal ____________ escaping from technical systems react in the atmosphere with water to _________________ . These then form - also with the rainwater - ________________________. - 31 - Acids in the pantry Acid rain: Who is responsible? Pollutant emissions in Germany (2003) sulfur dioxide (total: 0.62 million t) nitrogen oxides (total: 1.43 million t) 1. First, describe what is shown in the diagrams, what types of diagram are involved and which Values ​​you can read! 2. Now interpret the diagrams against the background of the question posed above. In doing so, specifically address the question of what options there are for the various decision-makers (e.g. your family, industry, politicians, ...) to reduce the acidity of the atmosphere! - 32 -