Calculations Formula mass MgO C3H7OH Ca(OH)2 CH3COOC4H9 24 + 16 =40 3x12 + 7x1 + 16 + 1 =60 40 + 2x(16 + 1) =74 12 + 3x1 + 12 + 2x16 + 4x12 + 9x1 = 116

Equations and formula mass CH3COOH + C2H5OH  CH3COOC2H5 + H2O What mass of ethyl ethanoate can be made from 0.23 g of ethanol? Calculate formula masses of the compounds in the question C2H5OH = 2x12 + 5x1 + 1x16 + 1x1 = 46 CH3COOC2H5 = 12 + 3x1+12 + 2x16 + 2x12 + 5x1 = 88

Equations and formula mass CH3COOH + C2H5OH  CH3COOC2H5 + H2O What mass of ethyl ethanoate can be made from 0.23 g of ethanol? Calculate mass of unknown chemical from 1g known chemical 46g ethanol gives 88g ethyl ethanoate 1g ethanol gives 88/46g ethyl ethanoate Calculate mass of unknown from given mass 0.23g ethanol gives 0.23x88/46 = 0.44g

Equations and formula mass H3PO4 + 3 KOH  K3PO4 + 3 H2O What mass of potassium phosphate can be made from 0.56 g of potassium hydroxide? Calculate formula masses of the compounds in the question KOH = 1x39 + 1x16 + 1x1 = 56 K3PO4 = 3 x 39 + 1x31 + 4x16 = 212

Equations and formula mass H3PO4 + 3 KOH  K3PO4 + 3 H2O What mass of potassium phosphate can be made from 0.56 g of potassium hydroxide? Calculate mass of unknown chemical from 1 g known chemical 3 x 56 = 168 g potassium hydroxide gives 212 g potassium phosphate 1g potassium hydroxide gives 212/168 g potassium phosphate Calculate mass of unknown from given mass 0.56 g potassium hydroxide gives 0.56 x 212/168 = 0.71g

Concentration (g/dm3) = mass (g)/volume (dm3) 1 dm3 = 1000 cm3 1 cm3 = 1/1000 dm3 Calculate the concentration in g/dm3 0.25 g Na2CO3 in 100 cm3 15.0 g HCOOH in 500 cm3 0.25/0.1 = 2.5 g/dm3 15.0/0.5 = 30.0 g/dm3

mass (g) = concentration (g/dm3) x volume (dm3) 1 dm3 = 1000 cm3 1 cm3 = 1/1000 dm3 Calculate the mass of solute dissolved in 25.0 cm3 4.0 g/dm3 CH3COOH 27.3 cm3 10.0 g/dm3 H2SO4 4.0 x 25.0/1000 = 0.10 g 10.0 x 27.3/1000 = 0.273 g

Equations and formula mass HCl + NaOH  NaCl + H2O 25.0 cm3 0f 0.365 g/dm3 HCl is added to a conical flask using a __________. A few drops of phenolphthalein (an indicator) is added. NaOH is added from a ________ until the indicator produces a permanent pink colour. The process is repeated until two values within 0.20 cm3 are obtained – why is this necessary? The mean value was found to be 27.5 cm3 what is the concentration of the sodium hydroxide? Calculate formula masses of the compounds in the question NaOH = 1x23 + 1x16 + 1x1 = 40 HCl = 1x1 + 1x35.5 = 36.5

Equations and formula mass HCl + NaOH  NaCl + H2O 25.0 cm3 0f 0.365 g/dm3 HCl. NaOH is added. The mean value was found to be 27.5 cm3 what is the concentration of the sodium hydroxide? Calculate mass of the substance we have the concentration (g/dm3) and volume (cm3) for Mass HCl = conc x vol = 0.365 x 25.0/1000 = 0.009125 g Calculate the mass of unknown from 1 g of the known species 36.5 g HCl reacts with 40.0 g NaOH 1 g HCl reacts with 40.0/36.5 g NaOH = 1.096 g Calculate the mass of unknown required 0.009125 x 1.096 = 0.010 g NaOH Calculate the concentration Conc (g/dm3) = mass (g)/vol (dm3) = 0.01/(27.5/1000) = 0.364 g/dm3

Some key areas to revise Green chemistry: yield (equilibrium); feedstock sustainability; atom economy; by products; catalysts Bond energies: breaking bonds is endothermic (requires energy); making bonds is exothermic (releases energy to surroundings); Total energy (of system) = bonds broken - bonds made; negative = exothermic; positive = endothermic; energy level diagrams Reversible reactions and equilibrium: ⇌; dynamic equilibrium when rate forward = rate backwards Catalysts: speed up rate of reaction by providing alternative route with lower activation energy; catalyst is not used up

Some key areas to revise Acids Strong acids: fully ionise (dissociate) HCl (aq)  H+ (aq) + Cl- (aq) Weak acids: partially ionise (dissociate) CH3COOH (aq) ⇌ CH3COO- (aq) + H+ (aq) Reactions: CH3COOH + LiOH  CH3COOLi + H2O 2 HCOOH + Mg  (HCOO)2Mg + H2 2 C2H5COOH + CaCO3  (C2H5COO)2Ca + CO2 + H2O HCOOH + CH3OH  HCOOCH3 + H2O

Some key areas to revise Chromatography: Stationary phase Mobile phase (a solvent) Sample is in dynamic equilibrium between the phases More soluble samples travel further Rf = distance moved by sample/distance moved by solvent Paper chromatography: paper and water Thin layer chromatography (TLC): silica sprayed onto e.g glass and e.g. ethyl ethanoate Gas chromatography: liquid on beads and inert gas e.g. argon

Some key areas to revise Synthesis of ester Heat alcohol and carboxylic acid with acid catalyst under reflux: heat speeds up reaction; vertical condenser prevents reactants/products escaping Fractional distillation: condenser pointing down Removal of acidic impurities: tap funnel; mix product with aqueous sodium carbonate; impurities dissolve in aqueous layer which is tapped off Dry with anhydrous calcium chloride Fractional distillation

Some key areas to revise Organic chemistry Alkanes: CnH2n+2 e.g. methane CH4; unreactive because of strong C-C & C-H bonds; immiscible in water; burn to produce CO2 and H2O Alcohols: -OH e.g. ethanol C2H5OH; burn to produce CO2 and H2O; 2 CH3OH + 2 Na  2 CH3ONa + H2 Carboxylic acids: -COOH e.g. propanoic acid C2H5COOH; weak acid Ester: alcohol + carboxylic acid e.g. butyl butanoate C3H7COOC4H9 Fats/oils: esters of long chain carboxylic acids and glycerol; oils – unsaturated (contain >C=C<); kink causes lower melting point; fats – saturated; chains line up

Some key areas to revise Ethanol manufacture Fermentation of sugars: C6H12O6  2 C2H5OH + 2 CO2; feedstock renewable but it requires agrichemicals, water and land; 37oC and yeast; max 15-20%; needs to be distilled Genetically engineered organisms can produce ethanol from waste carbohydrate – reduces food issues Hydration of ethene: C2H4 + H2O  C2H5OH; crude oil feedstock is finite; 300oC and H3PO4 catalyst

Some key areas to revise Life cycle assessment Manufacture: feedstock (sustainable? Effect on landscape/environment?); energy - electrolysis; transport; pollution Use: pollution while driving; electricity generation Disposal: toxicity; reuse; recycle; landfill; reduce; reuse; recycle Making decisions What other factors might influence people’s decisions? Reactions of group 1 React with: water to form hydroxides (MOH) and hydrogen (H2); oxygen to form oxides (M2O) Reactivity increases down group React to form M+ ion by losing an electron: more electron shells reduce the attraction from nucleus