Lab Experience n. 2 Physical Properties

Tuesday 15th January 2013

Wednesday 16th January 2013

Wednesday 23rd January 2013

Lab Experience n. 2 Physical Properties 

Objective/Task: Perform the corresponding tests in order to determine the physical properties of the matter given. 

Procedure - Standard:

1. Draw a BLANK table to record all the result you are expecting to obtain. Here you have a template:

Sample	1	2	3	4
Name
Element/Compound
Chemical Representation (Symbol/Formula)
Smell (Y/N – Strong/Mild)
Colour
Shine
Aggregation State (Solid – Liquid – Gas)
Melting Point (high/low)
Boiling Point (high/low)
Magnetism
Combustibility
Solubility in water
Solubility in organic solvent
Reactivity vs H2O (water)
Reactivity vs OH- (Base)
Reactivity vs H+ (Acid)
pH aqueous solution

2. Look at the top of the labelling of the container to find the name of the sample. Write it down in the corresponding cell of the table. Determine if it is an element or a compound and write down the answer. 

3. Look at the left bottom corner of the labelling to find the chemical representation. Write down the formula in the corresponding cell. 

4. Open the container and with your hand try to pull the air to your nose. Write down if what you have smelled is strong or mild. In the case of not smelling anything write down Y/N. 

5. With a spatula or with a pair or tweezers take out some of the sample from the container to look at it in the light in other to see its colour, if it shines or not and its aggregation state. Write down the colour you see, if it hasn't got any colour write colourless. If it shines write 'Yes' and if it doesn't, write 'No' in the cell for the shine. In the cell for the aggregation state of the sample write down solid, liquid or gas depending on what you have.

6. Set up a bunsen burner, put a beaker with the sample you have on top, place a thermometer inside and keep moving it to get an average of  the temperature: if the sample you had is a solid record the temperature at which it turns to liquid state, it will be the melting point. If the sample is a liquid or it was a solid which had already reached its melting point, record the temperature at which it begins to bubble, this is indicative of the vapor pressure being equal in value to the external pressure. When you see it starts to bubble, record the temperature. This recorded temperature is the boiling point of the substance. Depending on the temperatures you recorded, write down high or low for the melting point and boiling point columns.

7. Pour some of your sample into one of the holes of laboratory palette, take a magnet and put them close to see if they attract. Write down 'Yes' or 'Not' in the corresponding cell.

8. Use the sample on the palette to test the combustibility. Get a laboratory lighter and give fire to the sample, depending on how easily the substance sets on fire write 'Yes' or 'Not' in the cell for the combustibility.

9. Pour some of the sample into a test tube and pour water into it as well. Shake the test tube and to test quicker if it is soluble put your thumb on top of the test tube as a stopper and move it up and down. If your cannot see both substances, if it is an homogeneous mixture write 'Yes' if it is not, write 'No' in the column of solubility in water. Use this test to see if there is a reaction between the sample and water and write what you observe.

10. Repeat this step but with organic solvent instead of water and fill the cell for the column of solubility in organic solvent.

11. Get a beaker with a base (OH-) and pour some of the sample into it. Shake it a bit, wait and see if there is any reaction. Write 'Yes' or 'Not' depending on what you see in the column of reaction vs base.

12. Get a beaker with some of the sample inside then pour an acid into it. Skake it and see if there is a reaction, write 'Yes' or 'Not' depending on what you see in the column of reaction vs acid.

13. Pour some of the sample into one of the holes of the palette, get a piece of pH indicator paper and put it inside the sample, look at the box of the indicator paper to see what does the colour you have obtained stands for. Write neutral, acidic or basic in the pH column depending on the colour and its meaning.

Examples: 

Particular procedure:

1. Draw a table with 18 horizontal rows and 3 columns. In the first row we put the name of the element or compound we are working with and in the rest of the rows we write the physical characteristics we are going to determine.
2. Take a piece of Lead from the bottle and write down the characteristics we can observe and test easily, such as element or compound, shine, smell, aggregation state, and using a magnet we can test its magnetism.
3. Get a 100mL beaker and pour just 20 mL of water more or less, and drop the Lead into it. We test its solubility and we write it down in the table in its specific column (Sol. W), and also in the r. vs. water, that is the reaction versus water.
4. Get a bottle of an organic solvent (Hexane) and pour 20 mL of it into a beaker. Then, get a piece of Lead and place it inside the beaker. Observe if it does dissolve or not, and write what you’ve seen in the table, in Sol. Org.
5. Look for its pH in aqueous solution in the labelling of its bottle. Because it is an element, it is better to look for it on the internet if it is not found in the bottle.
6. In order to determine the melting and boiling points is better to search their theoretical values on the internet. It takes less time and if you try to do it by yourself maybe you would do it wrong and also you could be burned in the worst case.
7. Take a beaker place a piece of Lead inside it and pour with extreme care 10 mL of acid. Observe the reaction and write it down in the table. Make sure you don’t smell the acid for a long time, it could be dangerous!
8. Repeat step 2 to step 5 for each of the other compounds, Glycerol and Potassium Bromide. Be careful during the experiment and make sure you do every step with accuracy.
9. Fill the blank table with your results and data. As it has been said if there is something missing look for it on the internet or in text books.

Results:
Table: To show all the physical properties of the samples we were given (Lead -Glycerol- Potassium bromide) and which we have determined during the experiment.

Sample	1	2	3
Name	Glycerol	Potassium bromide	Lead
Element/Compound	Compound	Compound	Element
Chemical Representation (Symbol/Formula)	C3H8O3	KBr
Smell (Y/N – Strong/Mild)	Y/N	Y/N	Mild
Colour	Colourless	White	Grey
Shine	No	No	No
Aggregation State (Solid – Liquid – Gas)	Liquid	Solid	Solid
Melting Point (high/low)	Low - 18.17ºC theoretical value	High - 730ºC theoretical value	High -327.46ºC theoretical value
Boiling Point (high/low)	High - 290ºC theoretical value	Very high - 1435ºC theoretical value	Very high - 1749ºC theoretical value
Magnetism	No	No	No
Combustibility or conductivity.	Comb.Yes – as rule of organic compounds	Cond.No	Conduc. Yes
Solubility in water	Yes	Yes	No
Solubility in organic solvent	No	Yes	No
Reactivity vs H2O (water)	No	No	No
Reactivity vs OH- (Base)	No	No
Reactivity vs H+ (Acid)	No	No	Yes
pH aqueous solution	Neutral	Neutral	Neutral

Pictures:

In this first picture you can see how we settled to start with the experiment. You can see the two bottles which were the samples to which we had to determine the physical properties. At the back you can see a set of test tubes to carry on the different test and experiments necessary for the determination of the physical properties. The spatula, the glass rod and the palette are also materials needed to perform the lab experience.

       These two pictures are the two labels that you can find on a commercial bottle or container. In this case is Potassium Bromide (KBr). With the data the labels give, you can at least complete the gaps for the name (Potassium bromide) chemical formula (KBr) and if it is an element or a compound (compound).

These images are the labels of a commercial bottle, in this case what it contains is Glycerol (C₃H₈O3). Now you know the name (Glycerol) the chemical formula (C₃H₈O₃) and that it is a compound and not an element.

    These are the labelings of the commercial bottle of Trichloromethane stabilized with ethanol which was one of the organic solvents we used in our experience to test if our samples where soluble in it, the other one was Cyclohexane.

Videos Testing the Samples:

Isabel Caro