Chemistry AS level Cambridge University pressBy: Danica Prinzessin (Danica Putri)
States of matterGas:1. No fixed shapeor volume2. Randomlyarraged3. Far apart, canbe compressed4. Move freely inall directionsLiquid:1. Follow the shape of thecontainer2. Close together3. Fixed volume4. Compressed slighty5. Arraged fairly randomly6. Limited movement in alldirectionsSolid:1. Fixed shape and volume2. Touching each other3. Can’t be compressed4. Regular arrangement5. Can vibrate only
The Gasseous StateKinetic Theory of Gases:1. The gas molecule move rapidly andrandomly.2. The distance between the gas moleculeis much greater than the diameter of thevolume.3. No attraction or repulsion between themolecules.4. All collision between particle are elastic.5. The temperature of the gas is related tothe average kinetic energy of themolecules.Ideal Gases:The volume depends on:1. Pressure, measure in pascals (Pa)2. Temperature, measure in Kelvin (K), 0celcius=273KGeneral gas equation:General gas equationGas pressureWhere:p=pressure [Pa; N / m2]V=volume [m3]m=mass [kg]M=molar mass [kg / kmol]R=general gas constant R = 8.314510 kJ /(kmol K)T=thermodynamic temperature [K]n=molecular number density [1 / m3]k=Boltzmanns constant k = 1.380 x10-23 J/KGeneral gas e.q combined with the gasslaw:
Limitations of the ideal gas laws:Real gas don’t obey the K.E.Theory in 2ways:1. There isn’t zero attraction between themolecules.2. Can’t ignore the volume of themolecules themselves.These differences are especially noticeableat very high pressures and very lowntemperatures, under this conditions:1. The molecule are close to each other.2. Not negligible volume compared withthe volume of the container.3. Van der Waals’ or dipole-dipole forcesattraction.4. Attractive forces pull the moleculestowards each other.5. The effective volume is smaller thanexpected for an ideal gas.Deviated to ideal gas: HClNot approaches ideal gas behavior: NH4Approaches ideal gas behavior: He
The Liquid StateBoiling Point:Liquid to Gass Energy transferred make the particles move faster. The forces attraction of the prticles weaker. The particle with most energy are the first toescape from the forces holding. Evaporates. Move fast and randomly , then the particles spreadout.Melting Point:Solid to LiquidThe particles vibrate more vigorously.The forces attraction of particles are weaker. Temperature is higher than 0 degreecelcius.Freezing Point:Liquid to SolidLoss kinetic energy.Increasing forces attraction of particles .
The Solid State Lattice:Ions, atoms, or molculesarrangement in the solidsubstance.Structure of solid1. Ionic latticesCharacteristic: Hard. Brittle. High melting points. High boiling points. Many of them are soluble in water. Only conduct electricity when molten orin solution.Giant Ionic: (e.g. NaCl, MgO) Dissolvent in water. Free ions. Conduct electricity.Ionic bond of NaCl, it alsoGiant ionic same as MgO
2. Metallic LatticesCharacteristic: The layers can slide over each other. Delocalised elestron. Lattice of kations. Shiny. Malleable. Conduct electricity. When the layer slide, new metallicbond are easily re-formed betweenions.
Mixture of 2 or more metals or metalwith non-metal.The metal added to create the alloybecomes part of the crystal lattice ofthe other metal.Characteristic: The presence of different sizedmetal ions makes the arrangementof tle lattices less regular. Layers can’t slide easily. Stronger than pure metal.e.g.1. Zinc 30% and Copper 70%.2. Aluminium with other elements (such ascoper, magnesium, silicone, manganese).3. Alloys
4. Simple molecularCharacteristic:Can forms crystals.Weak van der waals’ forces.Strong covalent bonds.Easily broken when heatedForms crystal lattice.Allotrops: different crystalline ormolecular forms of the same element.Hydrogen bond:H binds with element F,N, and OCharacteristic: High boiling point Interact with other atoms are negative orelectron-rich.Iodine crystal and its’structure
5. Giant mollecular structureGraphiteThe carbon atoms are arranged inplanar layer, form hexagon layers.Each carbon atom is joined to 3 othercarbon atoms by strong covalentbonds.4th electron of each carbon atomoccupies at p orbital.Softness, the layers can slide.Good conductor of electricity.High melting and boiling points.e.g. Pencil, lubricant.
Diamond Each carbon atom forms 4 covalentbonds with other carbon atoms. High melting points and boilingponts. Hardness. Doesn’t conduct electricity or heat.Artifical diamonds can be made byheating other forms of carbon underhigh pressure.
Silicon (IV)oxide Structure smiliar to diamond. Each oxygen atom is bonded to only2 silicon atoms. Each silicon atom is bonded to 4oxygen atoms. Colourless crystals. High melting point and boilingpoint. Doesn’t conduct electricity. Hardness.
6. CeramicsCeramics: An inorganic non-metallicsolid which is prepared by heating asubstance or mixture of substances to ahigh temperature.Characteristic: Very high melting point and boilingpoints. Don’t conduct electricity, they’reelectrical insulators. Don’t conduct heat, no freeelectrons. Retain strength at high temperatureabove 550 degree celcius(refractories). Hard. Unreactive chemically.
Uses of ceramics: Ceramics containing Magnesiumoxide: Refractory in furnace linings. Electrical insulators in industrialelectrical cabel. Fire resistant wall furnaces.Ceramics containing AluminiumOxide: Refractory in furnace linings. As an abrasive for grinding hardmaterials. In transparent aluminium oxide forfurnaces and military vechiles.Ceramics containing silicon(IV)oxide: Refractory in furnace linings. As an abrasive. Manufacture of glass.
Conserving material There is only a limited supply ofmetal ores in the earth. Huge wasre dumps and landfill sitesscarring the landscape and problemswith litter.Recycling advantages: Saves energy. Conserves supplies of the ore. Less waste. Landfill sites don’t get filled upfast. Cheaper than extracting themetal from the ore.
2 metals are easily to recycle:Copper and Aluminium.Copper:Less energy is needed to extractand refine the recycled copper.Less energy is needed to recyclecopper than is needed to transportcopper ore to the smelting plantand extract copper from it.Aluminium:Isn’t necessary to extract thealuminium is much cheaper thanextracting aluminium from bauxiteore.Doesn’t need the treatment ofbauxite.The aluminium scrap needs lessenergy to melt it.The expensive electrolysis ofaluminium oxide doesn’t need tobe carried out.