1 C2 Chemistry NANO-TECHNOLOGY OIL RIG Ionic Bonding Electrolysis: e.g. Water, Cl2, H2, HCl CH4, O2DiamondDelocalised electronsGiant Covalent StructureHigh melting and boiling points, hardStrong covalent bondsSimple moleculesLow melting and boiling pointsWeak intermolecular forcesDoes not conduct electricityGraphite only:Conducts electricity, softand slippery between layers.-it has delocalised electrons-C2 ChemistryCovalent BondingNon-metals sharing electionsNo chargeAn atom:Number of Protons = Number of ElectronsMass number = Protons + NeutronsPeriodic table arranges elements by ATOMIC NUMBER (proton number/the small one)OIL RIGOxidation is lose (of electrons)Reduction is gain (of electrons)Pure copperImpure copper(copper ore)Max 2 electronsMax 8 electronsE.g. 2,8,8 (Argon)The number of outer shell electrons match the group the element is found in.E.g. Lithium 2,1 is a group 1 element.Cu 2+Describe this!Copper purificationImpurities: include gold and silver (can be sold)Protons and neutrons both have a mass of 1Electrolysis:Splitting up a substance using electricityMetallic BondingExtracting Aluminium using electrolysisSea of delocalised electronsCan carry a charge so metals conduct electricityHalf equationsElectrolysis needs:2 electrodesAn electrolyte(Ionic or molten substance)A power supplyIons move toward oppositely charged electrodesRemember: Atoms like to end up with full outer shells.+ carbon electrodes need replacing as the corrode into CO2Ionic BondingWhen there are 2 possible productsThe less reactive forms at the electrodeAlloy’s are stronger then pure metalsaAdd cryolite to lower melting point.Lose or gain an electronGet a charge +/-Attract one another!ElectroplatingUsed for: Disinfectants, bleach and plasticsMetal ions only arranged in layersELECTROSTATIC ATTRACTION between+IONS and DELOCALISED ELECTRONSGroup 1Group 7Brine:Salt waterIs the negative electrodeUsed for: Margarine and HClUse to improve: Appearance, stop corrosion and save money!Electrolysis of BrineGroup 1 and 7 elements make good ionic partners, so do group 2 and 6!Metal ions slide over one another making them MALLEABLEMetals conduct HEAT wellUsed for: Bleach, paper and soapGiant Lattice StructureAlways metals with non-metals+ ION and – ION attracted by STRONG ELECTROSTATIC FORCESAs a solid: High melting and Boiling PointConducts electricity when melted or dissolved:Ions move freely and carry a chargeNANO-TECHNOLOGYMeans REALLY REALLY REALLY small !!!!!
2 When a reaction forms a SOILD(s) its called a PRECIPITATE Other techniques: Gas chromatography for separation, Mass Spectroscopy for identifying and finding molecular mass.Experimental AnalysisIdentifying what’s in a mixture.Paper chromatographyI’d love to tell you a good chemistry joke but all the good ones Argon Molecular ion peak =peak with the largest massISOTOPESare atoms of the same element with different numbers of neutronsRelative formula MassAdd the mass of each atom in the formula togethere.g. CaCO3= 100Why use a machine?AdvantagesDisadvantagesQuickExpensiveAccurateNeeds special trainingAnalyse small amountsInterpreted by comparison onlyWe compare the mass of any atom to Carbon 12Additives improve appearance, taste and make food last longer!Moles1 mole of any substancecontains the same number of particles (6.02x1023)Relative atomic mass or formula mass in grams is equal to one mole.e.g. 12g of carbon is one mole of carbonPlasticsUsing different monomers and conditions will change the type of polymer you produce.Hand warmers and self heating cans use exothermic reactions.Mixing two chemicals to produce heat (single use) or the formation of crystals in a supersaturated solution (reusable).Mass of elementTotal mass of compound x 100 = Percentage Masse.g. % mass of carbon (12) in ethane C2H6 (30)24 / 30 x 100 = 80%Thermosetting – don't melt !– melt easily when heatedThermosofteningCool packs use exothermic reactions – Good for sport injuries!All the carbon ( = 24)When a reaction forms a SOILD(s) its called a PRECIPITATEToo removed a solid (s) from a reaction you FILTER it out !Exothermic reactions give out heat to the surroundings(get hotter)e.g. Respiration &CombustionIf you reaction gives you a dissolved product (aq) instead, you EVAPOURATE it out !CatalystsIncreasing the rate of a reaction can save money!Different reactions need different catalysts!Catalysts are often metals(if they escape they might harm the environment)Endothermic reactions take in heat from the surroundings (get colder)- speed up reactions without being used upe.g. PhotosynthesisWe can measure the rate of a reaction by looking at how fast solid reactants are used up, how quickly gas is produced or how quickly light is blocked (the disappearing cross)e.g. Sulfuric Acid + Magnesium -> Magnesium sulfate+ HydrogenCollision TheoryReversible ReactionOne way will be endothermic and the other will be exothermicIn a closed system forward and backward reaction occur at equal ratese.g. Nitric Acid + Copper Oxide -> Copper nitrate + WaterThe rate of a reaction is speed up by increasing the:TemperatureSurface areaConcentrationOr by adding a CATALYSISAcidSaltHydrochloric AcidChlorideSulfuric AcidSulfateNitric AcidNitrateFor this:Anything that's not a metal on its own is a baseWhen we increase the concentration/surface area we increase the frequency of particles colliding and reacting. Speeding up the reaction.When we increase the temperature the particles move faster, they are more likely to collide and do so with sufficient energy to react. Speeding up the reaction.Acid + Metal Salt + HydrogenAcid + Base Salt + WaterSteep line = fast reaction Flat line = A reactions that’s stopped!IMPORTANTAcids & Bases (Alkalis)Increase in pressure is the same as increase in concentrationAcids – H+Alkalis – OH-An increase of 10oC doubles the rate of a reactionFor a reaction to take place we have to have the minimum amount of energy neededThe ACTIVATION ENERGYBases NEUTRALISE acidsAlkalis are soluble basespH ScaleFind the pH using Universal Indicator
3 Balanced Equations Molecular Formula & Empirical Formula Molecular Formula : The actual number of atoms of each element in an individual moleculeEmpirical Formula : The simplest whole number ratio of the elements in the moleculeCalculating the Empirical Formula1) Use the same table and method given for calculating reacting masses but remove the ratio row.The question will either provide the grams of each element or the percentage. Assume percentages are the same figure in grams.e.g. 12% = 12gPercentage YieldThis is used to compare our actual yield with our theoretical yield.Amount of product actually producedMaximum possible yield (Theoretical yield) x 100e.g. 200275 x = %Its rare to get 100% yieldThis is because some products can be left in apparatus or separating products from reactants is difficult.Sometimes it’s not everything reacts to begin with.Remember: Lots of waste reduces resources and cause extra pollution.A balanced equation has the same number of atoms for each element on both sidesWe can use this to find the ratio of moles that are needed to react with one anothere.g. 1 CH4 molecule reacts with 2 O2 molecules1:2 ratioWorking out chemical formula…Use your data sheet!Question: A substance contains 24% carbon and 64% hydrogen. Calculate the its empirical formula.When doing an experiment if we know the grams used and the Molecular/Formula Mass we can calculate the molese.g. In 24 g of carbon which has an Mr of 12 there would be 2 moles of carbon.24/12 = 2This is useful if we want to calculate how much product we would get from a specific amount of reactantTHEORETICAL YIELDWhen you need to work out the ionic formula of a substance you will always need something from the positive ion column and something from the negative ion column.gGramsChemicalCarbonHydrogenGrams2464Mr1216Moles24The charges should always cancel out!nMolesMrMolecular/Formula Masse.g. What is the formula for silver oxide?1) First identify the two ions you need. (one from each column)Ag+ and O2-2) Balance the charges. Oxygen has 2 minus charges but silver only has a single positive charge.This means you’ll need two silvers to cancel out the one oxygen.( + + ) Ag+ Ag+ = O ( - - )Calculating Theoretical yieldQuestion: How much CO2 would be produced by burning 100g ofMethane (CH4) ?What if you need something that already has a small number?Put the whole ion in brackets!Cu (NO3)22) To get the simplest ratio divide all moles by the smallest calculated value2/2 = /2 =1 : 2This gives you the number of each element present and the empirical formulaC H23) Write the formula. When you know how many of each ion you need use this in the formula and ignore the charges.Ag2OChemicalCH4CO2Ratio1Grams100?Mr1644Moles6.25Try to work out: Magnesium oxide and Calcium chloride…1) Put in the things you already know. You were given the grams of methane in the question. And can calculate the Mr using the periodic table.2) Use the triangle to calculate the moles or methane used.4) Now you have the Mr and the moles of CO2 you can use the triangle to calculate the grams that will be produced.44 x = 275Answer: 100g of methane would make 275 g of CO2Answers: MgO CaCl2All figures in example calculations refer to the burning of methane in oxygen as shown in the balanced equationIf you were told the compound had a mass of 28 you could calculate the molecular formulaThe Mr of CH2 is 1428 /14 = 2Therefore the molecular formula must be double the empirical one C2H43) Use the ratio from balanced equation to provide the moles of CO21 : : 6.25
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