Colloids
To introduce colloidal solutions and familiarise students with filtering techniques.
Cosa imparano gli studenti
La scienza alla base di questo esperimento
In the previous experiments the solutes were dispersed as molecules or ions throughout the solvent. It can happen that the solute does not dissolve completely but its molecules remain aggregated as small clusters; these solutions are called colloids and have different properties from true solutions.
Under certain conditions, it is possible to obtain colloids from a wide range of substances, such as metals, oxides and sulphides.
Some colloids, such as soaps, form micellar solutions where the solute exists as particles called micelles.
Attrezzatura utilizzata
- Provette — 1473,60
- Portaprovette — 1680.06
- Portaprovette — 5423.30
- Spatola — 5460.34
- Iron stand — 5404.52
- Universal clamp — 5416.20
- Right angle clamp — 5401.16
- Glass funnel — 1343.15
- Filter paper — 8340.08
Sostanze chimiche e reagenti
- Sulphur — R:11-16 S:41
- Ethanol — R:11 S:7-16
Note sulla sicurezza
Domande per gli studenti
- Describe the solution. What was it like before and after the addition of water?
- What happens to the solution after filtration? Why?
Cosa aspettarsi
<p>The sulphur dissolves in ethanol to give a clear, pale yellow solution. After adding water, the colloidal solution looks like a milky white solution.</p><p>The same results are obtained with milk that forms micelles with water molecules.</p><p>Filtration does not affect the solution because the sulphur particles are much smaller than the pores in the paper.</p>
Smaltimento
Dispose of liquids into the liquid wastes container.
Prova a fare questo esperimento in classe
Questo esperimento fa parte dell’ATP “ Mobile Lab ” — un laboratorio autonomo che trasforma una normale aula in un vero e proprio laboratorio scientifico, con oltre 200 esperimenti di fisica, chimica, biologia, robotica e ingegneria. “ Gali ”, il tutor basato sull’intelligenza artificiale integrato in ATP Connect, guida gli studenti in ogni fase e risponde alle loro domande direttamente al banco di lavoro.
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