WJEC CBAC AS/A LEVEL GCE in Chemistry REVISION AID UNIT 1 AS UNIT CH1 – Controlling and Using Chemical Changes (in order to make things‚ produce energy and solve environmental problems) Preamble This unit begins with some important fundamental ideas about atoms and the use of the mole concept in calculations. Three key principles governing chemical change are then studied‚ viz. the position of equilibrium between reactants and products‚ the energy changes associated with a
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wavelength associated with the particle depends on the particle’s momentum. Describing the interactions of the waves corresponding to individual electrons is at the heart of molecular wave mechanics. When the electron waves in a region of the molecule overlap in a constructive way‚ like water waves reinforcing each other‚ there is greater likelihood of finding the electrons in that region. The challenge is to describe this wavelike behavior in enough mathematical detail that we can accurately predict
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Introduction to the Lanthanides r understand that lanthanides differ in their properties from the s- and d-block metals; r recall characteristic properties of these elements; r appreciate reasons for their positioning in the Periodic Table; r understand how the size of the lanthanide ions affects certain properties and how this can r understand how to obtain pure samples of individual Ln3+ ions. 1.1 Introduction Lanthanide chemistry started in Scandinavia. In 1794 Johann Gadolin succeeded in
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AP Chem Exam - ‘98 1. Solve the following problem related to the solubility equilibria of some metal hydroxides in aqueous solution. (a) The solubility of Cu(OH)2(s) is 1.72 x10–6 g/100. mL of solution at 25° C. (i) Write the balanced chemical equation for the dissociation of Cu(OH)2(s) in aqueous solution. Cu(OH)2 Cu 2+ + 2 OH – (ii) Calculate the solubility (in mol/L) of Cu(OH)2 at 25 °C. (1.72 x10–6 g/0.100 L)(1 mol/97.5 g) = 1.76 x10–7 mol/L (iii) Calculate
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isotopes * Isotope: atoms with same # of protons but diff # of neutrons * Isotopic Abundance: % of an isotope in a sample of an element * Nuclear Charge: positive charge on nucleus (# of protons/atomic number) * Position of Outermost Orbital: dist. Btwn nucleus and valence e- (increases down cuz more lvls outweigh nuc charge‚ decreases across cuz same # o lvls‚ more nuc charge pulls elecs in) * Shielding Effect: extent to which elecs in inner orbits affect bonding of valence elecs
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assume that the final compound contains copper(II)‚ ammonia‚ sulfate‚ and water. In your analysis‚ you goal is to figure out the mole ratio of each component in the final compound. In other words‚ you will solve for x‚ y‚ z and a in the formula Cux(NH3)y(SO4)z • aH2O. Based on the way the formula is written you can assume that ammonia
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Earth‚ and Moon are aligned (in "syzygy") exactly‚ or very closely so‚ with the Earth in the middle. Hence‚ a lunar eclipse can only occur the night of a full moon. The type and length of an eclipse depend upon the Moon’s location relative to its orbital nodes. Unlike a solar eclipse‚ which can only be viewed from a certain relatively small area of the world‚ a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours‚ whereas a total solar eclipse
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Slide 10-4 Q4: Which of the following molecules is the most polar? Br Te Cl Br F Cl Te Br Br 1A) Te Cl Cl F Te F Cl F 2B) 3C) Br Br Te Br Cl 4D) Copyright © 2014 Pearson Canada Inc. Cl Cl Br 5E) Slide 10-5 Q5: Which orbitals overlap to form the sigma bond between the carbon and hydrogen atoms in the ethylene (H2C=CH2)? 1A) sp3 on C & 1s on H 2B) sp2 on C & 2s on H 3C) sp on C & 2p on H 4D) sp2 on C & 1s on H 5E) sp on C & 1s on H Copyright © 2014 Pearson Canada Inc. Slide
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INDUSTRIAL SCALE AMMONIA PLANT USING HYSYS™ Presented By Mohammad Shamsus Saleheen #0602001 Md. Abu Abdullah Al Hasanat #0602002 1 Outline of the Presentation Objectives Simulating an ammonia plant using Aspen HYSYS A simplified block diagram of Haldor Topsoe ammonia production process Steady-state Model Comparison of steady-state simulation results with real plant data Response of the Model to Changes in Process Variables Scope of future work 2 Objectives Building a steady-state
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Bonding In a covalent bond‚ a pair of electrons is shared between two atoms. Each of the positively charged nuclei is attracted to the same negatively charged pair of electrons. The diagram: A and B are held together by this shared attraction. Covalent bonds are often drawn as dots and crosses diagrams to show that the electrons have come from two different atoms. Molecules have a certain fixed number of atoms in them joined together by covalent bonds. Examples: Bonding in hydrogen
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