Mark Scheme (Results) Summer 2012 International GCSE Chemistry (4CH0) Paper 1C Science Double Award (4SC0) Paper 1C Edexcel Level 1/Level 2 Certificate Chemistry (KCH0) Paper 1C Science (Double Award) (KSC0) Paper 1C Edexcel and BTEC Qualifications Edexcel and BTEC qualifications come from Pearson‚ the world’s leading learning company. We provide a wide range of qualifications including academic‚ vocational‚ occupational and specific programmes for employers. For further information‚
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the base. H+(aq) + OH-(aq) H2O(l) When a weak acid is neutralised some of the energy is needed to dissociate the molecules to make the hydrogen ions available for neutralisation. The result is a value for neutralisation enthalpy lower than - 57 kJ/mol (numerically lower‚ not more negative!) Note that as the weak acid is in equilibrium as the hydrogen ions are ’mopped up’ by the base the equilibrium shifts to the right hand side to make more until eventually all of the acid is able to react
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| n-nonane | 35 | -54 | 151 | C10H22 | n-decane | 75 | -30 | 174 | The simplest organic compounds are hydrocarbons. Hydrocarbons contain only two elements‚ hydrogen and carbon. A saturated hydrocarbon or alkane is a hydrocarbon in which all of the carbon-carbon bonds are single bonds. Each carbon atom forms four bonds and each hydrogen forms a single bond to a carbon. The bonding around each carbon atom is tetrahedral‚ so all bond angles are 109.5°. As a result‚ the carbon atoms in higher alkanes
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form the shared pairs form covalent bonds with the hydrogen atoms. The remaining two pairs are unshared and have a greater repulsive effect than the shared pairs. The combined repulsive effect of the two unshared electron pairs produces an H-O-H bond angle that is smaller than the H-C-H bond angle (109.47 degrees) in methane or the H-N-H bond angle (107 degrees) in ammonia. Actual measurement of the bond angle in water is 104.5. If the two hydrogen nuclei were
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Summer Assignment – AP Biology – Chapters 2-5 Chapter 2 1. CHNOPS are the six most crucial elements in most macromolecules. Name them. Carbon‚ Hydrogen‚ Nitrogen‚ Oxygen‚ Phosphorous‚ Sulfur. 2. Create a chart and state how many bonds each of the CHNOPS elements can form. Carbon | Hydrogen | Nitrogen | Oxygen | Phosphorous | Sulfur | 4 | 1 | 3 | 2 | 3 or 5 | 2 | 3. Create a Venn Diagram to compare and contrast polar covalent bonds‚ nonpolar covalent bonds‚ and ionic bonds.
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Prashant Zanwar University of Central Florida I. Introduction To Maglev Technology And Application 1.1 Principle of Maglev System Maglev is a system in which the vehicle runs levitated from the guideway (corresponding to the rail tracks of conventional railways) by using electromagnetic forces between superconducting magnets on board the vehicle and coils on the ground. The following is a general explanation of the principle of Maglev. fig. 1.1 1.1.1 Magnetic Levitation The "8" figured levitation coils
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molecules in 6 moles of methane Number of Molecules = moles x molecules in 1 mole = 6 x 6.02 x 1023 molecules = 3.61 x 1024 molecules Calculate the number of molecules in: (a) 0.37 moles of sulphur dioxide (b) 3.4 moles of hydrogen chloride Answers (a) 2.23 x 1023 molecules (b) 2.05 x 1024 molecules Ions Ionic compounds do not contain atoms or molecules. Instead‚ we talk about ‘formula units’ The formula unit (f.u.) is the same as the chemical formula Calculate
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in yeast During respiration‚ hydrogen atoms are removed from glucose molecules by enzymes called dehydrogenases and passed to various chemicals called hydrogen acceptors. As the hydrogen atoms pass from one hydrogen acceptor to another‚ energy is made available for chemical reactions in the cell. In this way‚ substances such as glucose provide energy for vital reactions in living organisms. In this experiment‚ a dye called methylene blue acts as an artificial hydrogen acceptor. When this dye is reduced
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solids. Structure: The simplest saturated acyclic hydrocarbon is methane‚ CH4. The other hydrocarbons belonging to this class can be taken as descendents of methane‚ resulted from the substitution of one or more atoms of hydrogen with hydrocarbon radicals. Therefore‚ if one hydrogen atom from methane is replaced by a methyl radical‚ -CH3‚ the hydrocarbon (superior to methane) will have the composition C2H6‚ named ethane. The alkanes can be: with a continuous chain‚ if all the carbon atoms are bound
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1. Describe the nuclear fusion reaction that occurs in stars. Page 294 Stars are made primarily of the almond hydrogen the most common material universe. As a star forms‚ gravity pulls the hydrogen into a dense ball that heats up. Electrons are torn from the hydrogen and other atoms‚ creating a plasma made up primarily of protons (the nucleus of the hydrogen atom) and electrons. Normally‚ protons would repel each other. As matter accumulates ending the new star however‚ the protons move
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