Thermodynamics- Volume Increase Upon Neutralization

Volume Increase upon Neutralization

Two photos, each with three stoppered flasks. In  the first photo, a labeled flask contains clear liquid, a flask with a black band is empty, and a second labeled flask contains clear liquid. In  the second photo, the flask with the black band contains liquid that reaches above the black band and a layer of blue liquid appears at the bottom of the flask. The remaining two flasks are empty.

Description: When equal volumes of strong aqueous acid and base are mixed,  the resulting volume is more than the simple sum of the volumes, due to the formation of water.

Source: Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry

Year: 1989  Vol: 3  Page: 276

Keywords: Acid Base Chemistry, Water, Hydrochloric Acid, Sodium Hydroxide

Ratings:

Hazard: Medium

• Serious eye damage hazard
• Corrosive to metals
• Skin corrosion hazard
• Inhalation hazard
• Acute toxicity hazard

Effectiveness: Good

• Good connection from demo to course material
• Some contrast between system behavior
• Results can be observed with guidance
• Low failure rate
• Time to result is medium

Difficulty: Medium

• Careful manipulations required
• Procedures with some intermediate steps to results
• Demos in which a display is used
• Volume dependent addition for proper results

Safety Precautions:

• Gloves required
• Eye protection required
• Chemically resistant surface required
• Sodium bicarbonate on hand
• Absorbent materials on  hand
• Uses UL approved three-prong plug and outlet
• Perform in a well-ventilated area
• Prevent release of reagents to the environment

Class: Intermolecular Forces, Solubility, Properties of Solutions, Acid-base Reaction, Thermodynamics

Division: General, Physical Chemistry

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