Basic Lab Skills

Abstract:

In this practice, we did four experiments, the first one we calculated the lost amount of water in the copper sulfate pentahydrate been heated up by an hour approximately. In the second experiment, we pull apart SiO2 from water and NaCl by a decantation, then we move apart the water from NaCl by evaporate the water, next we calculated the mass of the NaCl and the SiO2 to see how many mass did they lost. After that, we removed the pigment from six different M&M’s colors with a solution of ethanol and water, to measure how much the pigment displaced when the paper soaked up with the same solution of ethanol and water. At the end of the practice, we did a fourth experiment witch we saw the way that the para-benzene sublimated from a solid to a gas and vice versa.

Introduction:

Chemists often need to separate mixtures of two or more substances. Because a mixture is a physical combination of materials, the components may be separated using physical changes. There are different ways of accomplishing such a process. One common laboratory technique involves distillation, where substances having different boiling points are separated. Another common technique makes use of differences in the solubility of the components of the mixture.

SUBLIMATION: Sublimation is the process by which a solid changes from the solid to the gaseous state directly without forming a liquid. Melting is a process by which a solid changes to a liquid by heating. In the mixture used in this experiment, one compound, ammonium chloride sublimes easily, while the other

two components do not.

SOLUBILITY: The extent to which a substance is soluble in a solvent depends upon the chemical structure of boththe substance and the solvent. In general, polar compounds, such as sugar and alcohol, and ionic compounds, such as KCl, NaCl, NH4Cl, and NH4NO3, are soluble in polar solvents such as water. Nonpolar substances such as grease, wax, and oil, are soluble in nonpolar solvents such as toluene or kerosene. Extracting (dissolving) a soluble substance out of a mixture with a appropriate solvent is a common separation technique. In this experiment you will use solubility to extract a solid, NaCl, which is soluble in water, from another solid, SiO2, which is insoluble in water.

DISTILLATION: If two components have very different boiling points, the substance with the lower boiling point will evaporate more rapidly at a given temperature than the substance with a higher boiling point, and so they can be separated on this basis.

Objective:

Know the different separation techniques in order to choose the more effective in the separation of a

mixture of components.

Experimental Procedure:

Results and Data:

Case 1 Porcelain Capsule: 47.53g, 0.521mg

- Procedure

1. We weight the porcelain capsule

2. Weight 0.5g of copper sulfate

3. We put the 0.5g of copper sulfate in the stove for one hour at 80°C

4. We take out the copper sulfate and leave it for 15 minutes to cool

5. We fill the table 1

Case 1

Mass, m(g)

Mol, n(mol)

Molar relation

CuSo₄

0.156

9.73x10^-4

H₂O

0.365

0.020

Case 2

- Procedure

1. We weight 0.25 of NaCl and 0.25 of SiO₂ and put it in the porcelain capsule

2. We add 5mL of distilled water and mix all for 1 minute

3. The SO₂ and the NaCl separate

4. We separate the solution

5. Add 5mL more to the NaCl to separate it perfectly

6. Again, add 5mL of water to the first capsule. Repeat this step two times

New weight of NaCl = 0.23g

We lost 0.15g

Compound

Mass

Mass porcentage

Sodium Chloride (NaCl)

0.158g

63% (the NaCl stick in the bitter)

Silicon Dioxide (SiO₂)

0.23g

...