C1.4 Fractional Distillation and Chromatography Flashcards

1
Q

What separating technique is needed to separate different liquids with similar boiling points?

A

➢ Fractional distillation

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2
Q

How does a fractionating column aid separation of ethanol and water?

A

➢ The temperature in the column is highest at the bottom
➢ A substance with a higher boiling point will condense more readily on the cooler glass beads nearer the bottom of the column
➢ Then drip back down into the flask beneath
➢ The substance with lower boiling will continue rising and pass into a condenser and can be collected

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3
Q

What is the boiling point of ethanol?

A

➢ 78 degrees

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4
Q

What is the boiling point of water?

A

➢ 100 degrees

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5
Q

What liquid would be collected in a mixture of ethanol and water?

A

➢ Ethanol because it has a lower boiling point

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6
Q

What is ethanol used as?

A

➢ A biofuel

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7
Q

What technique is needed to separate substances from mixtures in a solution?

A

➢ Chromatography

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8
Q

What is the 1st step in paper chromatography?

A

➢ Use a capillary tube to dab a spot of the solution on a pencil line near the bottom of the sheet

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9
Q

What is the 2nd step in paper chromatography?

A

➢ Paper placed in a solvent at the bottom of a beaker

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10
Q

What is the 3rd step in chromatography?

A

➢ Allow the solvent to soak up the paper running through the spot of the mixture

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11
Q

What can the Rf value be useful for?

A

➢ Identifying unknown chemicals if they can be compared to a range of reference substances

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12
Q

How do you calculate the Rf value?

A

➢ Distance travelled by the substance/ Distance travelled by the solvent

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13
Q

What is the stationary phase?

A

It is the paper

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