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Grade 99 grade science

WHAT ARE THE FACTORS AFFECTING MELTING POINT

Profile image of A M S ARUN KRISHNA
10 Years agoGrade 9
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2 Answers

Profile image of Abishek arun
ApprovedApproved Tutor Answer10 Years ago
factors affecting melting point
  • effect of pressure
  • addition of impurities
Profile image of deapan
10 Years ago
FACTORS AFFECTING MELTING POINT
  1. EFFECT OF CHANGE OF PRESSURE
The effect of pressure on the melting point of solid depends upon the nature of solid
For solids which expand on melting, increase in pressure increases the melting point. This is because increase in melting point opposes expansion. Examples: paraffin wax, silver, gold, copper. For solids which contract on melting, increase in pressure decreases the melting point. Examples: ice, cast iron, brass
Ice is a solid which contracts on melting, its melting point decreases. When two ice cubes are pressed together, the ice at interface melts due to the application of slight pressure. When pressure is released it solidifies again thereby joining the two ice cubes. This principle is called regelation.
ii)EFFECT OF ADDITION OF IMPURITIES
Addition of impurities to a solid decreases the melting point of solid
Example: Rose metal – allow of tin, lead and bismuth
Melting point of this alloy
94.50C
Melting point of this Pb
3270C
Melting point of this Sn
231.90C
Melting point of this Bi
2710C