Presentation on theme: "Write a SOP (standard operating procedure) for doing a titration"— Presentation transcript:
1Write a SOP (standard operating procedure) for doing a titration Bell WorkWrite a SOP (standard operating procedure) for doing a titrationDo not use your books Hints – diagram, use known/unknown/ tips
2ASE Presentation for New Users Big PictureAssessment at ASUnit F331Chemistry for LifeUnit F332Chemistry of Natural ResourcesUnit F333Chemistry in Practice (internal assessment)Elements of LifeDeveloping FuelsElements from the SeaThe AtmospherePolymer RevolutionFive practical skills15% of A level25% of A level10% of A levelWritten paper1 hr 15 minWritten paper (one question on an ‘Advance Notice’ passage)1 hr 45 minInternal assessment of skills using materials and mark schemes provided by OCR
4Content Process Benefit Learning OutcomesContent Process BenefitSkill of carrying out a titrationCalculate unknowns and percentage uncertaintyCarry out a titrationHelp in 10% of AS grade!
5ES4.1 Activity Carry out titration Put your results on the board Use the booklet to help write your results
6The question:10.0 cm3 of a solution of potassium hydroxide was titrated with a 0.10 M solution of hydrochloric acid cm3 of the acid was required for neutralization. Calculate the concentration of the potassium hydroxide solution.Step 1Write down everything you know from the question. I put the one we know most about on the leftHydrochloric Acid Potassium hydroxideVolume used = 13.5 cm3 Volume used = 10.0 cm3Concentration = 0.10M Concentration = TBDTBD to be determined
7Step 2Write the BALANCED equation (or as much as you know about it). HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)This is necessary to check out the ratios of reactants – in this case 1:1 so we don’t have to worry about any ratios.Step 3Calculate the Number of Moles used of the reactant you know most about. In this case the HCl(aq)The rule here is ;Number of Moles = concentration
8Step 3Calculate the Number of Moles used of the reactant you know most about. In this case the HCl(aq)The rule here is ;Number of Moles = volume × concentrationNever do cm3!
9Step 4Work out how many moles of the unknown you have used, this is where you may need to multiply up or down the number of moles, so if 1 mole of HCl needed 2 mol of potassium hydroxide, then at this point you would multiply the number of moles of HCl by 2. In this case this is unnecessary.Number of moles of HCl = molNumber of moles KOH = mol – they react in a one to one ratio
10Step 5 Work out the concentration of the potassium hydroxide.Moles of KOH (same as HCl as 1:1) –Volume (q) 10cm3Concentration = 0.14 MNumber of Moles = volume × concentration
11CH3COOH + NaOH H2O + NaOOCCH3 0.1M NaOH ? CH3COOHVolume 6cm3 10cm3Balance equationNo. moles = Vol dm3 x conc.? = (6/1000) x 0.1Moles dm-3? = 6 x 104 Moles1:1 ratio thus 6 x 104 Moles of acidSo Conc = Moles/vol dm3 = 6 x 10 4 / (10/1000)= Moles dm-3
12DemonstrateDeduce the concentration of hydrochloric acid if 20.0cm3 is neutralised by 25.0cm3 of sodium hydroxide at 0.2oo moldm-3?
13Carry out a titration? Confident with procedure? ReviewCarry out a titration?Confident with procedure?Confident with calculations?What to do if you’re not?
14Home LearningBest Choice – Salters A level / ES Formula, equations, amount / Titrations and titration calculationsNext lesson is halogen production conference – have poster with you and all qs+ ready to speak