Chemical Reactions in Red, White and Blue!

Author(s): Jen Klipfel and Nabila Jachan
Lab Kits-Teacher's Guide
SED 695B; Fall 2005

Overview: The purpose of this demonstration is to aid in the discussion of chemical reactions. The brilliant products created in red, white and blue are a great hook to interest the kids in what a chemical reaction is, how colored products are created from clear reactants, and the reactions open the avenue for discussion of how to balance equations.







Topics addressed:

1.Chemical reactions can cause color change.

2.Chemical reactions produce different products then the reactants one starts with.

3.Chemical reactions need to be balanced with all atoms represented in the reactants and products.

Safety**In all the above reactions ammonium hydroxide, as both a liquid and vapor, is extremely irritating-especially to eyes. Use a hood to dispense and have an accesible eye wash available. Toxic by ingestion and inhalation. Serious respiratory hazard**

In the first reaction, lead nitrate, clear, is mixed with clear ammonium hydroxide to make a white precipitate, lead hydroxide.
Safety**Lead nitrate is toxic by inhalation and ingestion; strong oxidant; dangerous fire risk in contact with organic material.**

In the second reaction, light blue cupric nitrate is mixed with clear ammonium hydroxide to make a royal blue copper complex, tetraamminecopper (II).
Safety**Cupric nitrate solution is toxic**

In the third reaction, phenolphthalein, clear in solution and clear in an acidic environment, turns pink to red in the basic environment of ammonium hydroxide.
Safety**Phenolphthalein is a flammable liquid and fire risk**

Standards Addressed:

Structure of Matter-eighth grade science

Each of the more than 100 elements of matter has distinct properties and a distinct atomic structure. All forms of matter are composed of one or more of the elements. As a basis for understanding this concept:

  1. Students know the structure of the atom and know it is composed of protons, neutrons, and electrons.
  2. Students know that compounds are formed by combining two or more different elements and that compounds have properties that are different from their constituent elements.
  3. Students know atoms and molecules form solids by building up repeating patterns, such as the crystal structure of NaCl or long-chain polymers.
  4. Students know how to use the periodic table to identify elements in simple compounds.

1. Place three 100ml beakers in a row across the demonstration table.
2. In the first beaker, add 15 drops of lead nitrate solution.
3. In the second beaker, add 20 drops of phenolphthalein indicator solution.
4. In the third beaker, add 15 drops of cupric nitrate solution.
5. In a 150ml beaker, measure out 140 ml of ammonium hydroxide solution.
6. When ready, add approximately equal amounts (47) ml of the ammonium hydroxide solution to each of the 100 ml beakers. Use the graduations on the beaker to estimate your measurements. The first solution should be blue, the second solution should be red, and the third should be white.
Disposal Procedure:
1. The contents for phenolphthalein reaction and cupric nitrate reaction should be neutralized and flushed down drain with excess water.
2. The contents for the lead nitrate reaction should be filtered. The filtrate should be neutralized and flushed down drain with excess water. The precipitate should be precipitated s the insoluble sulfide according to Flinn Suggested Disposal #27f.





Explain the chemical reaction that is taking place here. What are the reactants and what are the products?

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Phenolthphalein is an indicator that is colorless and clear in acidic solutions. Why does it turn red in the presence of ammonium hydroxide?

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Lead nitrate is reacts with excess OH- ions to form what white product?

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Here is the final product of all three visual chemical reactions.

References & Links:

This site below shows great visual of the copper nitrate reaction with ammonia

Below, this site shows nice pictures and video of lead nitrate reacting with ammonium hydroxide.

Below is a website that discusses indicators in more detail.

Here is a website that reviews chemical reactions and balancing equations and offers a "quiz" for students to check their understanding of how to balance equations.