1 S2/3 Chemistry Titrations
2 Learning Intentions We are learning how to carry out an accurate acid/base neutralisation reaction, using a titration technique. We are learning how to complete a volumetric titration calculation, which will allow unknown concentration of either an acid or an alkali to be calculated.
3 Success Criteria I can carry out an acid/base titration accurately.I can accurately dilute an acid/alkali. I can complete a volumetric titration calculation.
4 Titration When an acid and alkali react together, a salt and water are formed.
5 Titration When an acid and alkali react together, a salt and water are formed. It is possible to find out exactly how much alkali is needed to neutralise an acid by carrying out a titration.
6 Titration Equipment burette
7 Titration Equipment burette pipette
8 Titration Equipment burette pipette alkali acid
9 Titration Equipment burette Conical flask pipette alkali acid
10 Titration Equipment
11 Titration Method The pipette is used to accurately measure 25ml of alkali
12 Titration Method The pipette is used to accurately measure 25ml of alkali The alkali is placed in the conical flask and five drops of indicator are added.
13 Titration Method The pipette is used to accurately measure 25ml of 0.1 mol/l alkali The alkali is placed in the conical flask and five drops of indicator are added. Acid is added to the conical flask carefully using the burette
14 Titration Method The pipette is used to accurately measure 25ml of alkali The alkali is placed in the conical flask and five drops of indicator are added. Acid is added to the conical flask carefully using the burette The end point is reached when the indicator changes colour
15 Titration Calculationstart end Total (ml) rough 8.9 1st 8.4 2nd 8.2 The rough calculation is always discarded and an average Taken of the two remaining results.
16 Titration Calculationstart end Total (ml) rough 8.9 1st 8.4 2nd 8.2 The rough calculation is always discarded and an average Taken of the two remaining results. Average acid volume 8.3ml
17 Titration CalculationTitration calculations always start with a balanced equation
18 Titration CalculationTitration calculations always start with a balanced equation HCl + NaOH NaCl + H2O
19 Titration CalculationTitration calculations always start with a balanced equation HCl + NaOH NaCl + H2O 1 mol 1 mol 1 mol 1 mol
20 Titration CalculationCalculate the moles of alkali added N = c x v Number of moles n c v Volume in litres Concentration in mol/i
21 Titration CalculationCalculate the moles of alkali added n = c x v n = conc of alkali x volume in litres n = 0.1 x 0.25 N = moles
22 Titration CalculationAt the end point of the titration the number of moles of acid must equal the number of moles of alkali
23 Titration CalculationMoles of alkali = mole
24 Titration CalculationMoles of alkali = mole Moles of acid = moles
25 Titration CalculationCalculate the concentration of the acid Number of moles n c v Volume in litres Concentration in mol/i
26 Titration CalculationCalculate the concentration of the acid c = n = = 0.12mol/l v
27 Titration Calculationacid alkali PVC = PVC Power of acid Concentration of acid Volume of acid