(ASSIGNMENT 2B)
Introduction:
In this experiment I am going to work out the cooling curve for stearic
and paraffin wax and compare their melting points. A cooling curve is a
graph that shows when a substance changes state, for example from a
solid to a liquid, liquid to a gas, gas to a liquid and then liquid to a solid.
This is an example of a cooling curve where it shows when it changes
state.
A melting point is where the substance changes state and the molecules
have a lot of energy where the intermolecular forces between the bonds
will be strong enough to break and will have more space between them
for them to move around each other, this happens at the melting point.
Also evaluate the outcomes such as the temperature for both when the
substance has changed shape. This is an important step so we can see
what both of these substances have in common and what they don't
have in common and what that information can tell us .We are working
out the melting point so we can see how accurate our results are
compared to the ones online which other people have done and to see
what we can improve on if we ever do the experiment again next time.
Different states of matter:
There are different states of matter,solid,liquid and gas.
These states involve intermolecular forces.
,Intermolecular forces are the forces of attraction which are between
molecules that are near each other.
These intermolecular forces are weak compared to the forces that make
up the molecules such as the covalent(sharing electron between atoms
which occur mainly with non-metals) or ionic bonds(chemical bonds that
involves electrostatic force of attraction between metals and nonmetals)
between the atoms.(intermolecular)
The following diagram shows the different states of matter:
Solid is where the intermolecular forces arranged in a regular shape and
the molecules are close together and packed tightly.The molecules in a
solid cant move around past each other because of their tight structure
and there is not enough space between the molecules for them to move
around but they do vibrate a bit not much.These solid molecules have
strong intermolecular bonds which means they have strong attraction
between molecules which keeps the molecules close to each other.
Liquids structures are not as close and they are not as tightly packed as
solids.The molecules can move around each other but they stay together
because of the intermolecular forces between them.The liquid molecules
have a weaker intermolecular bond compared to solid molecules.
, Gas molecules are widely spread apart and they can move freely
because there are no intermolecular forces holding them together,this
furthermore suggests that gases have weak intermolecular force.
Changes of state:
This diagram shows the different changes of state:
Heating a substance means:
- it increases the kinetic energy of the molecules,
-They molecules start to vibrate
-the temperature increases
Cooling a substance means:
-The kinetic energy between the molecules decreases
-The molecules move and vibrate slower
-The temperature decreases
To go from a solid to a liquid state you have to melt, the solid molecules
will gain enough energy to break the strong intermolecular bonds and
will be able to move around each other, this usually happens at the
melting point.