Student Worksheet for the Demonstration
Sodium Reacts with Water
There is no more classic demonstration of chemical reactivity than sodium reacting with water. It is risky, involves fire, and almost never fails to please. But what are we meant to learn from it? Listen carefully to your demonstrator and then answer the following questions in discussion with your classmates. After witnessing the demonstration, view the Alkali Metals video from the Open University.
- What is the balanced chemical equation for the reaction you have witnessed?
- Describe metallic sodium. How is it like other metals and how is it different from other metals in your experience?
- What is the nature of the white smoke that is produced during the reaction? What hazards does it pose?
- Your teacher has added a pH indicator called phenolphthalein to the water. Phenolphthalein changes from colorless to pink when the pH rises above 9. Describe what you observed and, based on the chemical equation you wrote above, explain your observation.
- Sometimes this demonstration catches fire. What is it that’s burning? Write a chemical equation for this combustion.
- Fires require fuel, oxygen, and a source of ignition. What ignites the fire in the case of this demonstration?
- Why does your teacher, despite frequent requests, refuse to do the demonstration with a large piece of sodium?
- Sodium atoms change their electric charge in this reaction. Did the atoms gain or lose electrons? How many? Write a chemical equation.
- Based on the similarity of elements in the same group in the periodic table write chemical equations for the reaction of lithium with water and the reaction of potassium with water.