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14 Cards in this Set
- Front
- Back
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how do you check if two samples with the same melting point are the same sample? |
mixture melting point technique |
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if the melting point of the mixture is the same as that of the separate samples then what can be interpreted from this? |
they are the same sample |
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if the melting point of the mixture is lower and broader than the separate samples then what does this mean? |
the samples are different compounds |
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(pure/impure) compounds melt over a wider temp. range |
impure |
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"sharp" melting points mean a (pure/impure) sample |
pure |
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why must the device be slowly heated? |
so the thermometer, sample, and device can reach thermal equilibrium |
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when should you start and stop recording the temperature of the sample |
when it first begins to melt and when the last crystal disappears |
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until what temperature should you heat the device |
80C |
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at what rate should you slow the rate of temperature increase? |
2C/minute |
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what must happen for an IR model to be active? |
the polarity of molecule must change |
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absorptions below 3000cm-1 are due to _______ stretching |
C-H bond |
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the large peak above 3000cm-1 are due to _______ C-Hstretching |
O-H bond
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absorptions above 3000cm-1 are due to _______C-H stretching |
aromatic |
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what does the energy of transition depend on? |
the atoms and functional group |
