Experiment 2: Different tests.

Note: Just a couple weeks ago we were grouped in pairs and each pair was given three different compounds so they could carry out the same tests with each of the substances. As we are two pairs we have six substances although we will share the results of all our class.

Objective: to test several characteristics (smell, colour, shiness, aggregation state, melting point, boiling point, magnetism, combustibility, solubility in water, solubility in organic solvent, reactivity VS. water, reactivity VS. base, reactivity VS. acid, pH in aqueous solution and conductivity) of certain element/compounds.

Materials:

- Three different compounds/elements per pair.

- Bunsen burner.

- 6 test tubes.

- Test tube holder.

- Magnet.

- Lighter.

- Water.

- Organic solvent.

- Base.

- Acid.

- Stirring rod.

- Spatula.

- pH indicator paper.

- Safety goggles.

- Porcelain pot.

- Thermometer.

Procedure*:

--------------------------------Put on your safety goggles and your lab coats.---------------------------------

SMELL:

1.- Ask the teacher if it is safe for you to smell the compound/element. If it is safe write down whether the smell is none, mild or strong. If it is not safe for you to smell the compound/element the teacher should inform you if it is either, mild or strong.

COLOUR:

1.- Write down the colour of the compound/element or if it’s colourless.

SHINE:

1.- With the help of the light see if it shines (only applicable for solids and if it’s a metal make sure you scratch a bit the surface or you break it into pieces to see if it’s actually shiny in the inside).

AGGREGATION STATE:

1.- Write down if the compound/element is solid, liquid or gas.

MELTING/ BOILING POINT:

[We have not performed this in the lab as it is a dangerous process plus some substances we were using had really high boiling points which could not be reached with equipment in the lab. Although, if we were to perform it, we should follow the next steps:

1.- Put some of the compound/element into the test tube.

2.- Connect the bunsen burner to the gas and turn the gas on.

3.- Open the bunsen burner and lit it up.

4.- Heat up the test tube with the bunsen burner flame. The test tube must be tilted but make sure there’s nobody near you when doing so.

5.- In order to record the temperature at which it melts/boils you could use a thermometer, if the temperature is low, or a temperature sensor, if the temperature is higher but not too high.]

MAGNETISM:

1.- Take the magnet and a little bit of each compound/element. Put the magnet near it and see if the compound/element moves or is attracted towards the magnet.

COMBUSTIBILITY:

1.- Place a bit of the compound/element on the porcelain plate.

2.- Turn on the burner.

2.- Set fire to the element/ compound ( before doing so make sure there are no organic compounds in the table nearby where you are performing the experiment). In case it burns you need to make a note on how the flame is (the colour it has, its height...)

SOLUBILITY IN WATER/ REACTIVITY VS WATER/ pH IN AQUEOUS SOLUTION:

1.- Take the compound/ element and pour it into a beaker with water. Observe if any reaction between the water and the solute takes place. If there is any take note.

2.- With the help of a stirring rod, mix the two parts of the solution. If they cannot be mixed, the solute is not soluble in water.

3.- If you have obtained a solution, cut a bit of indicator paper and touch with it the solution. Write down the pH it indicates by the colour it turns to.

SOLUBILITY IN ORGANIC SOLVENTS:

1.- Pour some of the element/ compound into the test tube.

2.- Choose any organic solvent you have at your disposal (like, for example propanol or butanol) and pour some of it into the test tube.

3.- Write down if they mix or not (you may need the help of a stirring rod to be sure).

REACTIVITY VS OH^- (base)

1.- Pour part the base (OH^- ) in a test tube.

2.- Introduce the component/compound, in order to see if it reacts or not.

REACTIVITY VS H⁺

1.- Pour part the acid (H⁺) in a test tube.

2.- Introduce the element/compound, in order to see if it reacts or not.

CONDUCTIVITY:

1.- Take each of the element/compound and put them, if they are solid, on the porcelain pot or, if they are liquid, in a test tube.

2.- Take the conductivity tester and touch with the ends of it the element/compound. If the bulb lights up, the element/compound conducts electricity, if not, it doesn’t conduct electricity.

* As in this experiment we are testing different characteristics of the compounds/elements you don't have to follow a fixed order like you should in other meaning that the order in which you carry out the test doesn't matter but you must follow the steps in each single test.

PROCESSING DATA:

Table 1: table showing the different compounds/elements of which we (meaning all the students in our class) have tested the different characteristics.

VIDEOS:

Video 1: First part collecting all the test we carryed out.

Video 2: Second part collecting all the test we carryed out.

Video 3: Reaction of sodium and water.

CONCLUSION:

In the conclusion we would want to discuss several points:

- During the performance of this experiment we wrote down some results that we did not expect. Like the fact that four of our six elements/compounds didn't dissolve in water or that some of them didn't combusted when we expected they will do so.

- The performance of this experiment has not been as difficult as others could be but it has been very tedious as it was a very long experiment because we needed to test several things of many different elements/ compounds.

- We think that if we perform the experiment in another occasion we would be much faster and accurate as we would know what is better to be done after what and how to do things correctly.