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10 Cards in this Set
- Front
- Back
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what happens in both acid-base and redox titrations? |
a solution of known concentration is reacted with a solution of unknown concentration, and the unknown concentration is found through a calculation. |
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what is potassium manganate (VII) and how can it be used in a redox titration? |
-strong oxidising agent (accepts electrons) -used in redox titration to find concentration of solutions containing iron(II)ions or hydrogen peroxide. |
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why is no indicator required for this ? |
because the distinct purple colour of potassium manganate(VII) dissapears as it reacts. |
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what is the typical potassium manganate(VII) procedure? |
-use pipette to transfer known volume of test solution into a conical flask -acidify solution with dilute sulfuric acid -slowley add potassium manganate(VII) to solution in conical flask with burette, swirling gently, until pale pink colour persists. -repeat until you have 2 titles within 0.1cm3 |
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what happens during the titration? |
iron(II) ions are oxidised to iron(III) ions and manganate(VII) ions are reduced to manganese(II) ions. |
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what is the ionic equation for this reaction? |
5Fe2+(aq)+MnO4-(aq)+8H+(aq)-->5Fe3+(aq)+Mn2+(aq)+H2O(l) |
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what are iodine-thiosulfate titrations often used for? |
to find the concentrations of solutions of oxidising agents. |
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how is an iodine-thiosulfate titration usually carried out? |
-known amount of oxidising agent reacts with an excess of acidified potassium iodide solution. -iodine produced is then titrated against a standard solution of sodium thiosulfate. -near end a few drops of starch solution is added, giving intense blue/black colour which dissapears at end point. |
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give the equation for this reaction |
2 S2O3 2-(aq)+I2(aq)-->S4O6 2-(aq)+2I-(aq) |
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what can iodine-thiosulfate titrations be used for in a practical sense? |
to estimate the concentration of bleach solutions |
