Heating and Cooling Curves Flashcards
What is a heating or cooling curve?
it is a simple line graph which shows state changes a substance undergoes with increasing or decreasing temperatures.
What does the X axis represent?
time is measured on the X axis
What does the Y axis represent?
temperature is measured on the Y axis
What happens when a substance is heated?
it absorbs energy and this causes the substance to change state
What is the melting point of a substance?
0 degrees C
What is the boiling point of a substance?
100 degrees C
When a solid is heated, what is reached?
a plateau is reached when a solid meets its melting point. When this happens, the temperature remains constant
How is the heat supply being used up?
by changing the state of the substance by overcoming the forces of attraction between the particles.
With further increase in temperature, the liquid will now turn into a …….
gas, at this point boiling occurs and the temperature would remain constant
Describe what the melting point is?
the melting point is an important physical property of a compound. It can be used to identify a substance and its an indication of the property of the substance. Pure substances have specific melting, freezing and boiling points.
How does a substance containing impurities melt?
usually over a range of temperatures and not a specific temperature
Describe the melting and freezing points for pure substances?
the melting or freezing point is the temperature which the solid and liquid states of a substance can exist in equilibrium (REACTANTS AND PRODUCTS ARE CONSTANT)
For pure substances……..
Melting point- Freezing Point
Boiling Point- Point of condensation
