Titrations Flashcards

All titration types in AH chemistry

1
Q

What does EDTA do?

A

Form stable complexes consisting of mostly metal ions

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2
Q

What is EDTA used for?

A

It can be used to determine the metals present in complexometric titrations.

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3
Q

How can the end point of a EDTA complexometric titration be detected?

A

By a metal ion indicator (Organic dye that changes colour when it binds with metal ions)

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4
Q

When is a metal ion indicator suitable in an EDTA titration?

A

The indicator must bind less strongly with metal ions than it does EDTA, one indicator that does this is murexide.

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5
Q

Why is EDTA generally used as it forms complexes with metal ions in what ratio?

A

1:1

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6
Q

When EDTA is added to the solution what happens to the indicator?

A

It is displaced

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7
Q

When all the indicator attached to the metal ions has been displaced what is observed?

A

A colour change, this indicates the end point of the reaction

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8
Q

What is murexide a good indicator for?

A

Calcium and nickel ions

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9
Q

What kind of reactions are acid-base titrations?

A

Neutralisation reactions

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10
Q

What does a choice of indicator depend on?

A

The pH equivalence point

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11
Q

What is the end point/ equivalence point?

A

The point at which the reaction is just complete

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12
Q

What is a redox titration based off of?

A

Redox equations

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13
Q

What do redox reactions involve?

A

The transfer of electrons from the reducing agent to the oxidising agent

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14
Q

What is the end point colour for Potassium permanganate?

A

Very pale pink/ colourless

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15
Q

What does Sodium dichromate act as?

A

It’s own indicator as it’s colour changes from orange to green

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16
Q

What is used when a direct titration is not possible?

A

A back titration

17
Q

What does a back titration involve?

A

A known but excess amount of one standard reagent to a known mass of the substance being determined (the analyte). When this reaction is complete the excess amount of the standard reagent is determined by titration against a second standard reagent. Moles of the excess reagent which have reacted can then be determined.

18
Q

When are back titrations used?

A

When the analyte is insoluble or has low solubility e.g. aspirin

19
Q

What does a back titration control experiment used for?

A

To validate the back titration. This involves the use of a solution of known concentration

20
Q

When are titrations concordant?

A

When within 0.1cm cubed of each other