Question

An experiment similar to this was first created in 1994 at a time when phenolphthalein was still available in over the counter products. Design a flow chart for identification of the 10 compounds below, assuming that phenolphthalein is the only pH indicator available to you. Phenolphthalein changes from colorless to pink in the range рH 8 to 10. NaCI, CaCO₃, cornstarch, Na₂CO₃, NaHCO₃ glucose, sucrose, MgSO₄, NaOH, CaSO₄

Answer 1

To identify compounds with phenolphthalein, add it to each solution. If it turns pink, the compound is a base like NaOH. No color change indicates further testing for neutral or acidic substances; carbonates can be distinguished by their reaction with acids.

Step-by-step explanation:

The objective is to design a flow chart for the identification of ten compounds using phenolphthalein as a pH indicator. Phenolphthalein changes from colorless to pink in the pH range of 8 to 10, indicating a basic solution. To identify each compound, follow these steps:

1. Add a small amount of phenolphthalein to a solution of the unknown compound.
2. If the solution turns pink, the compound is a base (e.g., NaOH).
3. If there is no color change, the compound does not significantly affect pH and could be neutral or acidic.
4. For those compounds without a color change, further tests such as solubility and reactivity might be necessary to distinguish between them (e.g., NaCl, CaCO₃, cornstarch, glucose, sucrose, MgSO₄, and CaSO₄).
5. Compounds that are carbonates (Na₂CO₃ and NaHCO₃) will react with acid, producing CO₂ gas. This can be an additional test to differentiate them from other non-reactive compounds.

Using this process, you can identify the unknown compound based on its reaction with phenolphthalein and other characteristic reactions.