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Questions after a bio test

Arctic
in Homework Help

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Hi

 

I have just conducted a test for fats using gresase spot test at biology class. But I don't quite understand why will the translucent spot (cooking oil) disapear after immersing into organic solvent.

 

The test procedure:

 

1. Transfer a drop of cooking oil to a filter paper and let it dry in the air for 5 minutes.

 

2.Hold up the filter paper to light and observe any translucent spot.

 

3.Immerse the filter paper into an organic solvent. Take it out and let it dry.

 

4.Examine the filter paper against light again. Note any change in the filterpaper. Use egg white solution and distilled water as controls.

 

thanks in advance.

Fat is insoluble in water, but it is soluble in non-polar solvents.

So basically, the spot disappeared because the fat was dissolved.

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