Question

One day in Chemistry lab. while performing an experiment to determine the melting point of ice,a student observed that melting point did not come out to be 0 degree Celsius.He asked his teacher about the cause for the same.His teacher told him that *



1)Melting point decreases due to presence of impurities

2)Melting point increases due to impurities

3)Melting point decreases because ice taken was less.

4)This is not possible​

Answer 1

Hi friend!

Your answer is Option 1 : Melting point increases due to impurities.

Hope it helps you!!

Answer 2

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$\large{ \sf{ \green{1) \: melting \: point \: decreases \: due \:}}} \\ \large{ \sf{ \green{to \: presence \: of \: impurities....}}}$

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$\Large{\underline{\underline{\tt{\pink{Explanation \: \:of \:\:Q. \: \: and \:\:A. }}}}}$

The student was not able to find the melting point, a exact 0°C, because the ice was impure. The ice must be solidified from impure water, for which the melting point decreases and ice melted at lower temperature.

Addition of impurities lowers the melting point. Why? It is because when impurities are added, they get into the minute,extremely tiny spaces between the atoms/molecules and weakens the intermolecular/interatomic force of attarction. As this force weakens, the body becomes less stable. The impurities disrupts the pattern of solid(also known as lattice), thus we can say that impurities lowers the melting point of solid. For better understanding, I have an example for you:

Rose metal ⇢ Alloy of tin, lead and bismuth.

♦️Melting point of this alloy = 94.5 °C

• Melting point of Pb ⇢ 327° C
• Melting point of Sn ⇢ 231.9 °C
• Melting point of Bi ⇢ 271 °C

So here, we can see that melting point of alloy is less than that of each constituents, Here constituents are the impurities only.

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