16- Melting point and purity
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/9
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced | Call with Kai | Chat |
|---|
No analytics yet
Send a link to your students to track their progress
10 Terms
How can the purity of an organic solid be tested?
Determine its melting point or melting range and compare it with a quoted value.
What does a very pure sample have as its melting point?
A sharp melting point at the quoted data-book value.
What happens to melting point when impurities are present?
The melting point is lowered.
What happens to the melting range when impurities are present?
The sample melts over a range of several degrees Celsius.
What can count as an impurity after recrystallisation?
Residual solvent.
Why should the sample be heated slowly near its melting point?
To obtain an accurate melting point.
What can cause an error when measuring melting point?
The thermometer temperature may not be the same as the actual temperature of the sample.
What equipment can be used to measure melting point?
An electronic melting point machine or a capillary tube attached to a thermometer in heating oil.
What properties should the heating oil have?
A boiling point higher than the sample's melting point and low flammability.
What is the key exam phrase for impurities?
“Impurities lower the melting point and cause the sample to melt over a range.”