Class X Question 1: Chapter 1 – Chemical Reactions and Equations Science Why should a magnesium ribbon be cleaned before burning in air? Answer Magnesium is very reactive metal. When stored it reacts with oxygen to form a layer magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper to remove this layer so that the underlying metal can be exposed into air. Question
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Polymerase chain reaction The Polymerase chain reaction (PCR) is a biochemical technology in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude‚ generating thousands to millions of copies of a particular DNA sequence. Developed in 1983 by Kary Mullis‚ PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. These include DNA cloning for sequencing‚ DNA-based phylogeny
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HOW ARE REDOX REACTIONS DIFFERENT? Redox is the term used to label reactions in which the acceptance of an electron (reduction) by a material is matched with the donation of an electron (oxidation). A large number of the reactions already mentioned in the Reactions chapter are redox reactions. Synthesis reactions are also redox reactions if there is an exchange of electrons to make an ionic bond. If chlorine gas is added to sodium metal to make sodium chloride‚ the sodium has donated an electron
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Iodine-Clock Reaction: S2O82−(aq) + 2 I−(aq) → I2(aq) + 2 SO42−(aq) To measure the rate of this reaction we must measure the rate of concentration change of one of the reactants or products. Here‚ it is convenient to carry out a clock reaction involving the product I2. To do this‚ you will include (to the reacting S2O82− and I−) i) a small (but accurately known) amount of sodium thiosulfate‚ Na2S2O3‚ and ii) some starch indicator. The added Na2S2O3 does not interfere with the rate of above reaction‚ but
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Erin Bolton Chemistry Lab Report April 29‚ 2015 Lab: Reaction Rates Introduction: In this experiment we studied the reaction of potassium persulfate‚ K2S2O8‚ with potassium iodide‚ KI. All chemical reactions have an energy barrier to overcome before the reaction will proceed. We will record data based on the concentration‚ temperature and catalyst for each experiment. Once this has been completed it will be graphed. Procedure: Due to the chemicals being used having hazard gloves are used
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Abstract “Reaction Time” is the interval of time between the application of a stimulus and the detection of a response and has been thought to differ based upon the effects of modality and warning signals. In the “Reaction Time” experiment a total of 24 students from the University of Cincinnati participated in an experiment consisting of two sensory modalities‚ audition and vision‚ which were combined with two levels of warning signal status. The two levels of warning signal status were signal
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rate of reaction (mol dm-3 s-1) for the following chemical reaction: CaCO3(s) + HCl(aq) CaCl2(s) + H2O(l) + CO2(g) Research question: How does altering concentration (mol dm-3) of hydrochloric acid (HCl) affect the rate of reaction (g/s) for the following reaction: CaCO3(s) + HCl(aq) CaCl2(s) + H2O(l) + CO2(g) Background information: The reaction between calcium carbonate and hydrochloric acid is an example of a neutralization reaction between an acid and a base. Neutralization reactions involve
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Week 10: Oxidation and Reduction Reactions: The Reactions of Copper Data: Part I: Preparing a solution of copper (II) nitrate Initial mass of copper wire: .520g Mass of copper wire after vigorously scouring: .518g Observations of Copper (II) ribbon mixed with HNO3: Solution turned green. Thick brown gas formed. Copper (II) bubbled vigorously. Cu (II) dissolved‚ solution appeared green/blue. After the addition of H2O a blue crusty precipitate formed. Part II: Synthesis of solid copper
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RATE OF REACTIONS. The reaction rate (rate of reaction) or speed of reaction for a reactant or product in a particular reaction is intuitively defined as how fast or slow a reaction takes place. For example‚ the oxidative rusting of iron under the atmosphere is a slow reaction that can take many years‚ but the combustion of cellulose in a fire is a reaction that takes place in fractions of a second (right). Chemical kinetics is the part of physical chemistry that studies reaction rates. The concepts
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chemical reactions using physical and chemical properties and balanced chemical equations. There are four different types of chemical reactions decomposition reactions‚ single displacement reactions‚ synthesis reactions‚ and double displacement reactions. A decomposition reaction happens when a compound breaks into two or more elements or compounds. Generally‚ for decomposition reactions heat‚ energy‚ light or electricity is needed to separate the compound. In a single displacement reaction‚ a single
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