Demo Questions:

Hydrogen Gas Preparation and Properties

1. What are the names and chemical formulas of the reactants used in this demonstration?
2. What are the names and chemical formulas of the products made in this demonstration? One of these is a gas but the other is an ionic compound that dissolves in the water.
3. Identify the type of chemical change which produced the hydrogen gas in this demonstration. Also, write a balanced chemical equation.
4. What is inside the bubbles produced when the hydrochloric acid is added to the zinc?
5. Why were the flasks full of water while the hydrogen gas was generated and bubbled into them?
6. Why did the flask full of hydrogen have to be held upside-down?
7. During the demonstration the hydrogen gas participated in a second chemical reaction. Identify the type of reaction and write a balanced chemical equation for it.
8. The flask produced a loud sound when a lit candle was brought close to its mouth. Why did this happen?
9. Why did the candle go out when it was inside the flammable hydrogen gas?
10. The candle flame returned to the wick when it was pulled it out of the flask. Explain how this worked.