how can we use melting points to tell whether or not a substance is a pure or mixture?
2007-02-27 10:46:42 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
well, at a particular melting point, a pure element will melt. If it is a mixture or elements, it will react before the melting point or melt after. For example, if you melt copper at 1235 degrees Celsius, then melt copper oxide (red powder) (copper exposed to oxygen) at 1084.62 degrees Celsius, this proves that the pure element reacts differently from the mixture and that is how you tell the difference.
2007-02-27 11:12:29 · answer #1 · answered by Chiky 4 · 0⤊ 0⤋
Find the melting point of the sample you're interested in testing.
Look up the melting point of the pure substance from a site like www.acros.com.
Compare the differences in melting points of the substances. Your actual lab value will often be lower than the the literature value, but a big difference in the two values (positive or negative) indicates that your sample is unpure.
2007-02-27 18:56:36 · answer #2 · answered by Mina C 2 · 0⤊ 0⤋
Ice melts faster if you pour salt on it... If the melting point is lower than usual, you know that the water was not pure.
2007-02-27 18:56:06 · answer #3 · answered by Anonymous · 0⤊ 0⤋