The properties of substances
and their bonding
Objective
To study, evaluate and compare the
properties of several substances and relate them to their type of bonding
(ionic, covalent or metallic).
Theoretical
background
The properties of substances are
related to the kind of bonding present in those substances. The type of bonding
depends on the atoms present and is related to their position in the periodic
table.
Materials
Substances A to D Conductivity meter
Test tubes Distilled water
Spatula Acetone
Bunsen burner
Method
Repeat the procedure for each of the substances
provided:
1. Take ½ a spatula of the substance in
a test tube. Describe the appearance of the substance.
2. Gently heat it in the flame of the
Bunsen burner and state if the approximate melting point. (Low, intermediate or high).
3. Take ½ a spatula of the substance in
another test tube.
4. Add 10 mL water, stir it and state
whether the substance is soluble in water or not.
5. Repeat the steps 4 and 5 using
acetone instead of water.
6. Using the conductivity meter, state
if the substance is a conductor in solid state.
7. If it the substance is soluble in
water, test whether the solution is a conductor or not.
Blog tasks
The whole
report must be posted to your group blog. Make sure you include:
Annotations:
1.)
Paraffinà the appearance of this substance is extremely
thick granules. Are rounded little white balls. This substance has a low
melting point.
2.)
Salt (NaCl)à the appearance of this substance is small,
white and thin granules. It has a very high melting point.
3.)
Starchà the appearance of the substance is very small,
white and dust-appearance. It has a high melting point; the substance is
getting burning and not melted.
4.)
Magnesiumà the appearance of the substance is a small
squared piece of metal. It has a very high melting point.
Now we need to do the same step but instead of
melting them, we need to see if it is soluble in water.
1.)
Paraffinà it has a low melting point but it is not
soluble in water because it is hydrocarbon.
2.)
Saltà it has a high melting point but is soluble in
water.
3.)
Starchà it has a high melting point, and it is not
soluble in water; the water gets a white colour not transparent.
4.)
Magnesiumà It has a high melting point and it’s not
soluble in water.
Now we
do the same steps but instead with water with some acetone.
1.)
Paraffinà the paraffin is not soluble in acetone; it
gets at the bottom of the test tube.
2.)
Saltà the salt is not soluble in acetone; it gets at
the bottom part of the test tube.
3.)
Starchà the starch is not soluble in acetone.
4.)
Magnesiumà this element is not soluble in acetone.
Now we need
to see if the substances conduct electricity.
1.)
Paraffinà the paraffin is not a conductor of
electricity.
2.)
Saltà the salt is not a conductor of electricity.
3.)
Starchà the starch is not a conductor of electricity.
4.)
Magnesiumà this element is a conductor, it conducts
electricity.
1.
A table of results.
SUBSTANCES
|
SOLUBILITY IN WATER
|
SOLUBILITY IN ACETONE
|
MELTING POINT
|
CONDUCTIVITY OF ELECTRICITY
|
TYPE OF BONDING
|
PARAFFIN
|
NOT SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
LOW MELTING POINT
|
NOT A CONDUCTOR OF ELECTRICITY
|
COVALENT BONDING
|
SALT
|
SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
HIGH MELTING POINT
|
NOT A CONDUCTOR OF ELECTRICITY
|
IONIC BONDING
|
STARCH
|
NOT SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
HIGH MELTING POINT
|
NOT A CONDUCTOR OF ELECTRICITY
|
IONIC BONDING
|
MAGNESIUM
|
NOT SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
HIGH MELTING POINT
|
A CONDUCTOR OF ELECTRICITY
|
METALLIC BONDING
|
2.
The type of bonding present in each
substance.
Paraffin: covalent bonding
because covalent bonding requires a low melting point (because I only need
enough energy to overcome the weak forces of attraction/ the melting point is
low)
Salt: salt is ionic
bonding because ionic bonding requires a high meting point (because we need to
break all the strong electrostatic attractions. This requires a lot of energy)
Starch: As well as salt,
it has ionic bonding because it has a high meting point.
Magnesium: Metallic
bond. The forces of attraction between the metal Cations and the 'sea' of
delocalised electrons.
3.
A secondary table to show “expected”
results. (Research the type of bonding and the expected results for the test that you carried out)
SUBSTANCES
|
SOLUBILITY IN WATER
|
SOLUBILITY IN ACETONE
|
MELTING POINT
|
CONDUCTIVITY OF ELECTRICITY
|
TYPE OF BONDING
|
PARAFFIN
|
SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
LOW MELTING POINT
|
NOT A CONDUCTOR OF ELECTRICITY
|
IONIC BONDING
|
SALT
|
SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
LOW MELTING POINT
|
NOT A CONDUCTOR OF ELECTRICITY
|
IONIC BONDING
|
STARCH
|
SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
LOW MELTING POINT
|
NOT A CONDUCTOR OF ELECTRICITY
|
IONIC BONDING
|
MAGNESIUM
|
NOT SOLUBLE IN WATER
|
NOT SOLUBLE IN ACETONE
|
HIGH MELTING POINT
|
A CONDUCTOR OF ELECTRICITY
|
METALLIC BONDING
|
4.
A conclusion comparing the actual
results with the expected results.
When we
start doing the experiment we thought that some of the elements would have more
or less melting point, would have more or less electricity… So our results have
been the ones that we expected, where we have made an error is in the theme of
the conducting electricity, we thought that some of them would conduct but none
of them do.
5.
An evaluation that suggest
improvements that could be made to your method.
-We could be
confused putting the results of every substance.
-We could make
confusion when we were looking at the substance: if it really was melted or
not.
-The time
of seeing at the (for example) the melting point, with the acetone, with the
Bunsen burner….
-We could
have more or less quantity in the volumetric flask than it was necessary.
6.
A minimum of 2 references (APA format).
Anon,
(2014). [online] Available at:
http://www.chemistry.sc.chula.ac.th/bsac/Org%20Chem%20Lab_2012/Exp.1[1].pdf
[Accessed 4 Oct. 2014].
Answers.com, (2014). What
factors affect the solubility of a particular substance. [online] Available
at: http://www.answers.com/Q/What_factors_affect_the_solubility_of_a_particular_substance
[Accessed 4 Oct. 2014].
