Sample Paper – 2012 Class – X Subject –Chemistry Chemical Equations and reactions Very Short Answer (1 marks each) Write the name and formula of compounds forms between a. Potassium and iodine ion .b.Sodium and sulphide ions . c. Aluminums and chloride ions 2. Why does milk sour when kept for a long time/ 3. What happen when hydrogen combine with oxygen in presence of electric current/ 4. Define electrolysis. 5. What is decomposition reaction? Give an
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Balancing chemical equations 1. Complete the following sentences‚ using the words or groups of words in the box below. You may use some words more than once. |• as small as possible |• decrease |• molecules |• quantities | |• balance |• different |• nature |• rearranging | |• bonds |• equal
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12-STANDARDIZATION OF SODIUM HYDROXIDE Standard solutions for titrations are especially pure mixtures with exactly known concentrations. Primary standards are very pure solids. They have the advantage that they can be weighed (the analytical balance is normally the most accurate instrument in the laboratory) and they are stable under laboratory conditions. In this experiment‚ the primary standard is oxalic acid dihydrate‚ H2C2O4 ( 2H2O. It will be used to standardize a solution of sodium hydroxide
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Investigation of Action of Saliva and 3 M Hydrochloric Acid in Two Carbohydrate Solutions Title : Investigation of Action of Saliva and 3 M Hydrochloric Acid in Two Carbohydrate Solutions Objective : To investigate the action of saliva and 3 hydrochloric acid in two carbohydrate solution Results Table1: Observation Conclusion Solution A Benedict’s test: Blue coloration turned to brick red precipitate. Reducing sugar is present in the solution A. Iodine test: The coloration remained
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Title : Investigation of Action of Saliva and 3 M Hydrochloric Acid in Two Carbohydrate Solutions Objective : To investigate the action of saliva and 3 hydrochloric acid in two carbohydrate solution Results Table1: Observation Conclusion Solution A Benedict’s test: Blue coloration turned to brick red precipitate. Reducing sugar is present in the solution A. Iodine test: The coloration remained unchanged. Starch is absent in solution A. Solution B Benedict’s test: The blue coloration
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ACIDS AND BASES The reason that acid-base reactions are so important is that many of the things you come into contact with on a daily basis are either acids or bases. Most fruits are acids‚ as are carbonated beverages‚ tea‚ and battery acid. Common household bases include baking soda‚ ammonia‚ soap‚ and antacids. What are acids and bases? There are not one but three common definitions used to describe acids and bases: 1. Arrhenius acids and bases 2. Brønsted-Lowry acids and bases 3. Lewis acids
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formula/molecular mass – Mr Most substances exist as; - compounds if ionic - molecules if covalent We can use Ar’s to calculate the ‘average mass of ONE unit of a substance’ this is called the Mr (see also topic 9) E.g. Calculate the Mr for sodium carbonate 3Na2CO3. Ar (Na) = 23 Ar (C) = 12 Ar (O) = 16 The number 3 in front of the formula has been ignored because by definition Mr is the mass of ONE unit of a substance whether the substance is ionic or covalent. Molar mass This
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The purpose of this investigation was to determine which type of alcohol (ethanol‚ butan-1-ol‚ or propan-2-ol) contains the most energy per gram. It was expected that if we burn three alcohols (ethanol‚ propan-2-ol‚ and butan-1-ol) for 2 minutes‚ then butan-1-ol will release the most energy per gram (J/g) because butan-1-ol contains more carbon atoms than other alcohols which means more energy is required to break its chemical bonds and more energy will be released when new chemical bonds are formed
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As a liquid evaporates‚ it lowers the temperature of the substances around them‚ because evaporation is an endothermic process. In the graph‚ each substance has a different curve. Some lowered the temperature much more than others. This is because different substances require differing amounts of energy to evaporate. To test this‚ the temperature change from the evaporation of 4 different alcohols was measured and compared‚ along with cyclohexane. Methanol had the largest change in temperature‚ 18
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KNES 470 Dr Rubin 4-18-12 Sodium Bicarbonate and Boxing Performance Boxing is a sport which relies on anaerobic power since it contains short-duration and high intensity work. A typical boxing match today consists of 3 minute rounds with a 1 minute seated recovery rest. When an athlete performs exercise at maximal level for more than 30 seconds‚ most of the energy comes from anaerobic glycolysis. During this process‚ lactic acid is produced which causes a decrease in pH levels within the muscle
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