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S2/3 Chemistry

S2/3 Chemistry. Titrations. Learning Intentions. We are learning how to carry out an accurate acid/base neutralisation reaction, using a titration technique.

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S2/3 Chemistry

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  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 Calculation The rough calculation is always discarded and an average Taken of the two remaining results.

  16. Titration Calculation The rough calculation is always discarded and an average Taken of the two remaining results. Average acid volume 8.3ml

  17. Titration Calculation • Titration calculations always start with a balanced equation

  18. Titration Calculation • Titration calculations always start with a balanced equation HCl + NaOHNaCl + H2O

  19. Titration Calculation • Titration calculations always start with a balanced equation HCl + NaOHNaCl + H2O 1 mol 1 mol 1 mol 1 mol

  20. Titration Calculation • Calculate the moles of alkali added • N = c x v Number of moles n c v Volume in litres Concentration in mol/i

  21. Titration Calculation • Calculate the moles of alkali added • n = c x v • n = conc of alkali x volume in litres • n = 0.1 x 0.25 • N = 0.025 moles

  22. Titration Calculation • At the end point of the titration the number of moles of acid must equal the number of moles of alkali

  23. Titration Calculation • Moles of alkali = 0.025 mole

  24. Titration Calculation • Moles of alkali = 0.025 mole • Moles of acid = 0.025 moles

  25. Titration Calculation • Calculate the concentration of the acid Number of moles n c v Volume in litres Concentration in mol/i

  26. Titration Calculation • Calculate the concentration of the acid c = n = 0.025 = 0.12mol/l v 0.0083

  27. Titration Calculation acid alkali PVC = PVC Power of acid Concentration of acid Volume of acid

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