Chemistry Ozone Depletion Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth’s stratosphere (the ozone layer)‚ and a much larger springtime decrease in stratospheric ozone over Earth’s polar regions. The latter phenomenon is referred to as theozone hole. In addition to these well-known stratospheric phenomena‚ there are also springtime polartropospheric ozone depletion events. The
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Chapter 1: Intermolecular Forces: Liquids‚ Solids‚ and Phase Changes Chem 11: General Chemistry 2 Topics 1.1 An Overview of Physical States and Phase Changes 1.2 Quantitative Aspects of Phase Changes 1.3 Types of Intermolecular Forces 1.4 Properties of the Liquid State 1.5 Uniqueness of Water 1.6 The Solid State: Structure‚ Properties and Bonding A hot spring on a snowy day The Kinetic Molecular View of the Three States The characteristic properties of gases‚ liquids
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be at least as large as the final pressure of the gas. P1 = 2.00 bar‚ V1 = 1.00 dm3‚ V2 = 0.500 dm3‚ P2 = ? = 4.00 bar This is the smallest value of Pext can be to compress the gas isothermally (constant temperature) from 1.00 dm3 to 0.500 dm3. Note: 1 bar = 105 Pa = 2.00 dm3 bar = (2.00 dm3 bar)(10-3 m dm-3)(105 Pa bar-1) = 200 Pa m3 = 200 J OR (in SI units) (4.00 x 105 Pa){(0.500 – 1.00) x 10-3 m3) = 200 J Of course‚ Pext can be any value greater than 4.00 bar‚ so 200
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Topic 6 Microscopic World II Unit 23 Shapes of molecules Unit 24 Bond polarity and intermolecular forces Key C o ncepts Microscopic World II Shapes of molecules • Covalent molecules with non-octet structures • Shapes of molecules • The VSEPR theory • Molecular crystals of buckminsterfullerene (C60) • Carbon nanotubes Bond polarity and intermolecular forces • Electronegativity and bond polarity • Van der Waals’ forces • Factors affecting the strength
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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Ordinary Level CHEMISTRY Paper 1 Multiple Choice May/June 2005 1 hour Additional Materials: Multiple Choice Answer Sheet Soft clean eraser Soft pencil (type B or HB is recommended) 5070/01 w w w e tr .X m eP e ap .c rs om READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples‚ paper clips‚ highlighters‚ glue or correction fluid. Write your name‚ Centre number and candidate number on the answer
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alligator clips. Make sure the tip of each lead is submerged in the green solution and the alligator clips remain out of the solution. Note: The solution in the Petri dish top will serve as a control. 4. To start the demonstration‚ clip the 9-volt battery into the snaps on the battery cap (Figure 1). 5. Let the demonstration run for 5–10 minutes and note the changing colors over time and the production of gases (bubbling) at each electrode. A deep purple color forms immediately at the
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Combustion of Acetylene (ethyne) Rx: Back Why I don’t do acetlyene explosions in our lab.... Combustion of alkanes A quick review.... • Combustion reactions of alkanes consist only of C and H (hydrocarbon) • require O2(g) as a reactant • produce CO2(g) and H2O(g) and a large amount of energy!! Oxygen can be the limiting reagent which can lead to Incomplete combustion. For complete combustion of a hydrocarbon‚ oxygen must be in excess. If there isn’t sufficient oxygen‚ incomplete combustion occurs
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Appendix APPENDIX 1 Chemical tests for functional groups Homologous series/ Typical compound Functional group(s) Alkanes CH3CH3 ethane C – C and C–H Alkenes CH2 = CH2 ethene C=C Chemical tests/Observations Add liquid bromine in ultraviolet light (or sunlight): White fumes of HBr liberated; decolourisation of bromine occurs slowly (a) Add Br2 in CCl4 at room temperature: Decolourisation of bromine occurs immediately CH2 = CH2 + Br2 → CH2BrCH2Br (b) Add acidified
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Wavelength () and frequency () are related according to the equation where is the speed of light (). The energy ( in joules) contained in one quantum of electromagnetic radiation is described by the equation where is Planck’s constant (). Note that frequency has units of inverse seconds ()‚ which are more commonly expressed as hertz (). Part A A microwave oven operates at 2.40 . What is the wavelength of the radiation produced by this appliance? Express the wavelength numerically in nanometers
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4.1 Defining the Atom Overview cannot be seen w/ naked eye def. smallest particle of an element that retains its identity in a chemical reaction Democritus’ Atomic Philosophy Democritus (460 BC- 370 BC) was a Greek philosopher first suggested the existence of atoms said they were indivisible and indestructible did not explain chemical behavior did not use scientific method John Dalton (1766-1844) English chemist schoolteacher used experimental methods he transformed Democritus’ ideas
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