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1)Sodium hydroxide is a strong alkali. In terms of ionisation, what is meant by the word strong? ( 1 mark) 2) You are given solutions of sodium hydroxide.

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Presentation on theme: "1)Sodium hydroxide is a strong alkali. In terms of ionisation, what is meant by the word strong? ( 1 mark) 2) You are given solutions of sodium hydroxide."— Presentation transcript:

1 1)Sodium hydroxide is a strong alkali. In terms of ionisation, what is meant by the word strong? ( 1 mark) 2) You are given solutions of sodium hydroxide and ammonia of the same concentration. Describe and give the results of a test to show that sodium hydroxide is a stronger alkali than ammonia solution. (2 marks)

2 1)Sodium hydroxide is a strong alkali. In terms of ionisation, what is meant by the word strong? ( 1 mark) completely ionised /dissociated

3 2) You are given solutions of sodium hydroxide and ammonia of the same concentration. Describe and give the results of a test to show that sodium hydroxide is a stronger alkali than ammonia solution. (2 marks) pH paper / (pH) meter (1) NaOH has higher pH or correct comparison of colours (1 mark)

4 Titration calculations L.O.:  Calculate the amount of acid or alkali needed in a neutralisation reactions

5 5 of 35© Boardworks Ltd 2009 What is concentration? The concentration of a solution is a measure of how much solute is dissolved per unit of solvent. amount of solute is measured in moles volume of solvent is measured in dm 3 concentration is measured in mol dm -3. concentration = amount of solute / volume of solvent Volumes are often expressed in cm 3, so a more useful equation includes a conversion from cm 3 to dm 3. concentration = (no. moles × 1000) / volume mol dm 3 cm 3

6 6 of 35© Boardworks Ltd 2009 Concentration, moles and volume

7 7 of 35© Boardworks Ltd 2009 Concentration calculations

8 8 of 35© Boardworks Ltd 2009 Titration calculations examples What is the concentration of an NaOH solution if 25.0 cm 3 is neutralized by 23.4 cm mol dm -3 HCl solution? 3. Calculate no. moles of NaOH: moles HCl = moles NaOH 4. Calculate conc. of NaOH: = ( × 1000) / 25.0 conc. = (moles × 1000) / volume = mol dm Calculate no. moles HCl: moles = (conc. × volume) / 1000 = = (0.998 × 23.4) / Determine ratio of NaOH to HCl: NaOH + HCl  NaCl + H 2 O ratio NaOH:NaCl = 1:1

9 9 of 35© Boardworks Ltd 2009 Titration calculations

10 Task: Worksheet (moles14) Workbook


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