MadSci Network: Chemistry
Query:

Subject: How do u differente between physical and chemical properties PLEASE READ!!!

Date: Fri Apr 21 16:15:35 2000
Posted by Kim
Grade level: 10-12 School: No school entered.
City: No city entered. State/Province: No state entered. Country: No country entered.
Area of science: Chemistry
ID: 956351735.Ch
Message:

Hello again, 
Is this right???

Physical Properties of Caffeine:

Qualitative Physical Properties:
 pure caffeine is a white, odorless powder
 crystallizes into long, white needlelike crystals
 the crystals loose their water of hydration slowly to give a white solid
 neutral to litmus paper
 bitter taste

Quantitative Physical Properties:
 molecular weight is 194.19g
 melting point is 238 C (460 F)
 point at which caffeine sublimes is 178 C (352 F) at atmospheric pressure
 pH is 6.9

Chemical Properties of Caffeine
 generally non-reactive
 soluble in hot water
 upon cooling, the solution deposits crystals of caffeine monohydrate

Are they in the right spot, I'm having trouble differentiating between 
physical and chemical properties.  Please respond, thanks a lot!!!

~Kim


Re: How do u differente between physical and chemical properties PLEASE READ!!!

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