Demo Questions:

Hydrogen Gas Preparation and Properties

1. Identify the chemical changes in the demonstration.
2. For each one identify the reactants and products. Write a chemical equation.
3. What is inside the bubbles produced when the hydrochloric acid is added to the zinc?
4. Why were the flasks full of water while the hydrogen gas was generated and bubbled into them?
5. Why did Mr. Keller keep the flask full of hydrogen upside-down?
6. The first flask produced a loud sound and flames inside the flask. Why did this happen?
7. Why did the candle go out when it was inside the flammable hydrogen gas?
8. How was he able to re-light the candle when he pulled it out of the flask?
9. Why didn’t the hydrogen in the flask burn up quickly? What did it do instead and why?
10. Liquid water is constantly evaporating at room temperature. Given that the hydrogen gas was collected by displacing water from a flask, what other gas shared space with it?