LAB REPORTS- PHYSICS AND CHEMISTRY

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].