Water clocks‚ along with sundials‚ are likely to be the oldest time-measuring instruments‚ with the only exceptions being the vertical gnomon and the day-counting tally stick.[1] Where and when they were first invented is not known‚ and given their great antiquity it may never be. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and in Egypt around the 16th century BC. Other regions of the world‚ including India and China‚ also have early evidence
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A ‘clock’ is an instrument used to specify‚ record‚ and manage time. The word ‘clock’ comes from the French word “cloche” meaning bell‚ came into use when timekeepers were kept in bell towers in the Middle Ages. Historians do not who or when mankind “invented” a time-keeping device or a “clock”. Probably thousands of years ago when someone stuck a stick in the ground and saw a shadow of the sun move across the ground‚ known as the sundial. (Cummings‚ 1997-2012). After the Samarian culture
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the form of a metal ion affect the rate of reaction in an iodide clock reaction with potassium peroxydisulphate ions? Background When peroxydisulfate ions (S2O82-) react with iodide ions (I-) in the presence of a starch indicator‚ they produce a dark blue solution. Reaction (1) S2O82- + 3I- I3- + 2 SO42- (peroxydisulfate ion) (iodide ion) (iodine ion) (sulfate ion) To determine the rate law for this reaction a series of changes in the concentration of
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In order to prepare the iodine solution titrant‚ exactly 50 mL of 0.01 M KIO3‚ exactly 20 mL of 10% KI solution‚ and exactly 25 mL of 0.3 M H2SO4 was transferred into a 100 mL volumetric flask using a volumetric pipette. The volumetric flask was then filled to the mark with distilled water. The flask was covered with Parafilm and inverted to mix. The next part of the experiment was to determine the Vitamin C in a solution of known concentration. Observations of the Vitamin C sample and the amount
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Iodine: Function of Iodine: Iodine is a mineral found in food. This mineral is needed to make thyroid hormones. The hormones created are used to control the body’s metabolism and lots of other important functions. The thyroid hormones are also used for bone and brain development during pregnancy and infancy. This mineral is important for everyone‚ especially infants and women who are pregnant. The amount of Iodine needed for your daily intake recommended of the mineral depends on your age:
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Iodine deficiency is a major threat to the health and development of the world‚ predominantly among toddlers and pregnant women in low-income countries. It is a significant public health problem in 130 countries and affects 740 million people. An estimated one-third of the world’s population is currently susceptible to the risk of iodine deficiency. Iodine is a vital nutrient for the proper functioning of the thyroid gland‚ which regulates growth and metabolism. Iodine deficiency is the primary cause
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INTRODUCTION Iodine deficiency disorders are still very much prevalent in the world today. Two billion people‚ estimated by the WHO‚ still lack a sufficient level of iodine in their diets which leads to a range of disorders known as iodine deficiency disorders (IDD). So what is iodine? Iodine is an essential micronutrient in the diet which is used by the thyroid gland (located in the throat) to produce thyroid hormones which help control the body’s metabolism. The two most important thyroid
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occurred in 1931. The electron microscope is used to see molecular levels of the cell that cannot be seen by the naked eye. This has helped us drastically improve our understanding of cells. 5. The discovery of the mechanisms of light-independent reactions of photosynthesis was discovered in 1953. This discovery helps us in understanding how plants work‚ and how they get energy from light. 6. The DNA structure was first discovered in 1953. This discovery has lead us to understand more about
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Iodine Test for Starch Introduction and Hypothesis: In this experiment‚ we used iodine to test for starch in certain solutions. Iodine separates starch from polysaccharides‚ monosaccharides‚ and disaccharides. Starch is a curled polymer of glucose and iodine interacts with molecules‚ which changes the color of the molecules to a kind of black color. Iodine does not respond with carbohydrates that are not curled or coiled‚ thus the color stays yellowish brown. A black color result means that starch
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62 Iodine test for starch Amount of starch remaining Enzyme activity level Dark blue-black All None (0) Blue Most Low (1) Light brown Some Moderate (2) Gold None High (3) Part 1: Effect of Enzyme Concentration 1. Label five test tubes 1-5. Place 4 mL of 1 % starch in each of the first four test tubes. Place 4 mL of amylase solution in the fifth tube. Place all of the tubes in the 37°C water bath for 5 minutes. Obtain 5 clean droppers and label them 1-5. (To avoid contamination of these solutions
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