Volumetric analysis Flashcards

1
Q

What are iodine thiosulphate titrations used for?

A

Used to determine the concentration of an oxidising agent

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2
Q

What are Iodine-Thiosulfate titrations used for?

A

To determine the concentration of an oxidising agent.

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3
Q

What is the typical method?

A
  1. 25cm3 of the oxidising agent is placed into a conical flask
  2. The mixture is acidified using sulfuric acid
  3. Solid excess potassium iodide is added
  4. The iodine in the conical flask is titrated with standard sodium thiosulfate solution
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4
Q

What is the colour change observed?

A

Brown colour fades to yellow, when straw colour reached a few drops of starch indicator added, the titration is continued until blue black turns colourless

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5
Q

What happens?

A

The oxidising agent is reduced and oxidised the iodide to iodine.

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6
Q

When using Iodate (V) ions:

  1. Write the equation for the reductio of Iodate (V) ions
  2. Write the oxidation for the oxidation of Iodide ions
  3. Write the overall ionic equation
  4. Give the ratio
A
  1. 2IO3⎻ + 12H+ + 10e⎻ → I2 + 6H20
  2. 2I⎻ → I2 + 2e⎻
  3. 2IO3⎻ + 12H+ + 10I⎻ → 6I2 + 6H20
  4. IO3⎻ : I2 is 1:3
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7
Q

When using Iodate (V) ions:

  1. Write the equation for the reductio of Iodate (V) ions
  2. Write the oxidation for the oxidation of Iodide ions
  3. Write the overall ionic equation
  4. Give the ratio
A
  1. 2IO3⎻ + 12H+ + 10e⎻ → I2 + 6H20
  2. 2I⎻ → I2 + 2e⎻
  3. 2IO3⎻
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8
Q

When using Hydrogen peroxide H2O2:
1. Write the equation for the reduction of Hydrogen peroxide
2. Write the equation for the oxidation of Iodide ions
3. Overall ionic equation
Give the ratio

A
  1. H2O2 + 2H+ +2e- → 2H20
  2. 2I⎻ → I2 + 2e⎻
  3. H2O2 + 2I⎻ + 2H+ → 2H2O + I2
  4. H2O2 : I2 is 1:1
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9
Q

What are some physical properties of potassium manganate?

A

Purple solid that forms a purple solution

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10
Q

What are some physical properties of potassium manganate?

A

Purple solid that forms a purple solution

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11
Q

What is the equation for the reduction of manganate ions

A

on page

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12
Q

What are potassium manganate titrations used for?

A

To estimate the concentration of a reducing agent

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13
Q

What is the method for potassium manganate titartions?

A
  1. 25cm3 of a solution of the reducing agent is place in a conical flask
  2. The mixture is acidified using sulfuric acid
  3. The standard solution of potassium manganate (VII) is added from the burette until the solution changes form colourless to pink
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14
Q

When using Oxalate ions, C2O4^2- :
1. What is the equation for the reduction of manganate ions
2. What is the equation for the oxidation of oxalate ions?
3. What is the overall ionic equation?
What is the ratio?

A
  1. MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
  2. C2O4^2- → 2CO2 + 2e-
  3. 2MnO4- + 16H+ + 5C2O4^2- → 2Mn2+ + 10CO2 + 8H2O
  4. MnO4- : C2O4^2- : 2:5
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15
Q

When using Oxalate ions, C2O4^2- :

  1. What is the equation for the reduction of manganate ions
  2. What is the equation for the oxidation of oxalate ions?
  3. What is the overall ionic equation?
A
  1. MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
  2. C2O4^2- → 2CO2 + 2e-
  3. 2MnO4- + 16H+ + 5C2O4^2- →
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16
Q

What is the colour change observed at the end of Iodine-Thiosulfate titrations

A

Blue-black to colourless

17
Q

What is the colour changed observed at the end point of Potassium manganate titrations?

A

Colourless to pink