Inquiry Activity: Do large and small molecules behave exactly alike?
Please do the following procedure as a group at your table:
1) Label 6 test tubes 1, 2, 3, 4, 5, & 6.
2) In place a small amount of tofu in test tube 1, soy sauce in 2, butter in 3, soap in 4, starch in 5, and sugar in 6.
3) Fill in the appropriate substances in the data table.
4) Half fill each test tube with water from the sinks (be sure to turn a small trickle on before putting your test tube under the flow).
5) Put a stopper on each of the test tubes.
6) Shake each test tube for 2 minutes.
7) Record your observations in the data table. Include the "Solubility Rating Scale" number for each substance and graph it on the gride provided.
8) Please carefully clean your test tubes using test tube brushes and soap. Suspend them on the drying rack sparkling clean and rinsed.
Solubility Rating Scale:
Solubility Rating 1 2 3 4 5 Descripitions Substance & water do not mix and stay completely separate. The substance remains in chunks or globs. Substance seems to at least break into smaller pieces but is suspended evenly in the water Substance seems to dissolve but is still visible. The particles are small enough they are hard to see individually Substance appears to dissolve but discolors the water because the particles have not completely disappeared Substance completely dissolves and disappears in the water
Test Tube # Substance Solubility Rating Scale (1-5) Qualitative Observations (of mixing with water) 1 2 3 4 5 6
Graph: Please make a proper bar graph (title, label both X and Y axis, use appropriate scale) of the solubility ratings for each substance.
Graph of Substance Solubility
1) Which substances dissolved easily in water?
2) Tofu, starch, and butter are made mostly of very large molecules.Soy sauce, sugar, and soap contain mostly small molecules. Are large or small molecules more soluble in water?
3) What is the evidence for your answer on question 2?
4) Why do you think this happens this way?