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26 Cards in this Set
- Front
- Back
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What mixture is being separated via simple distillation? |
1:1 ratio of acetone and 1-propanol |
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When is simple distillation used to separate liquids? |
1. liquids that have boiling point differences greater than 50 degrees 2. Separate volatile liquids from solids |
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What information is obtained from the gas chromatographs? |
1.) Area 2.) Mole percent 3.) Retention time |
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Is equilibrium vapor pressure directly proportional to temperature? |
Yes |
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What happens when equilibrium vapor pressure of liquid equals the atmospheric pressure? |
The molecule's boiling point is reached |
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What is associated with compounds that have a higher equilibrium vapor pressure? |
They have lower boiling point |
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What is associated with compounds that have a lower equilibrium vapor pressure? |
They have higher boiling point |
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What does volatile mean? |
Readily vaporizes at relatively low temperatures (high equilibrium vapor pressure) |
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Can intermolecular forces affect boiling points? |
Yes |
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What are intermolecular forces primarily influenced by? |
1) Bond dipoles 2) Molecular dipoles |
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What is the reason for the main difference in boiling points between acetone and 1-propanol? |
The main difference in boiling points is due to hydrogen bonding present in 1-propanol |
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What is a dipole-dipole interaction? |
Interaction between the positive end of a polar molecule and the negative end of a polar molecule |
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What is hydrogen bonding? |
Type of dipole-dipole interaction that involves H being bonded to N,O, or F |
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How many fractions do we need to collect? |
Collect three fractions |
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What consists of fraction 1? |
Relatively constant temperature |
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What consists of fraction 2? |
Dramatic change in temperature |
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What consists of fraction 3? |
Relatively constant temperature after dramatic rise in temperature |
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What consists of the mobile phase for GLC? |
Gas/vapor (helium) |
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What consists of the stationary phase for GLC? |
Liquid (carbowax) |
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What does Kc depend on in gas chromatography? |
Polarity of the solute and stationary phase |
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What is typically the mobile phase in gas chromatography? |
Helium or hydrogen |
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Is Kc influenced by equilibrium vapor pressure? |
Yes |
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Lower boiling point is associated with smaller Kc, which means shorter retention time.... True or False |
True |
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Higher boiling point is associated with a higher Kc value, which means longer retention time.... True or False |
True |
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What is thermal conductivity? |
The ability of a substance to conduct/transfer heat |
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What is the solid support in Gas chromatography? |
Diatomaceous Earth aka celite |
