Kitchen Chemistry Experiment 8
Production of Hydrogen

How do you produce a gas? What are some of the properties of hydrogen? How do you test for hydrogen?

 

Materials	Substitutions
mossy zinc	galvanized nail
hydrochloric acid	muriatic acid
small test tube	small jar
stopper	lid
wood splint	toothpick
beral pipets	droppers
candle and matches

Procedure

 

1. Place a galvanized nail in a glass jar.
2. Use the beral pipet or medicene dropper and fill (one squeeze full) with 3M HCl (muriatic acid).
3. Squeeze the HCl onto the zinc nail. Gas bubbles will be apparent. Place the lid or stopper on the jar loosely .
4. After 20 seconds, light the candle and prepare to test for the gas.
5. BE CALM! Place the burning splint into the jar JUST AFTER removing the stopper or lid. WOW!!! Replace the lid a wait for more gas to collect.
6. Relight the splint and test for the gas again.

 

Extensions

1. Write the equation for the reaction occurring in the above experiment.
2. What happened when the burning splint was placed near the hydrogen?
3. Why must we use a stopper or lid to collect this gas?
4. Why was hydrogen replaced by helium in the large air ships in the zeppelin or divigible 1920's and 1930's?

 

 

Teacher's Notes

During the sixteenth century Paracelsus, a Swiss-German physician, noted that a flammable gas was formed when iron reacted with sulfuric acid. He did not realize that the gas was a pure substance. In 1766, Cavendish determined that the flammable material was a distinct substance when he was able to produce the gas by reacting a variety of acids with several metals. However, it was Lavoisier that named the gas hydrogen which means "water producer".

Hydrogen is produced when an active metal replaces this element in an acid. This reaction is called a single replacement reaction.

Zn (s) + 2HCl (aq) ---> ZnCl2 (aq) + H2 (g)

Hydrogen is lighter than air so we must use a stopper or lid to keep it from escaping.

For large commercial ventures hydrogen is generally produced by the electrolysis of water. Hydrogen is liberated at the cathode when a direct current is passed through water containing a small amount of an electrolyte.

 

Solution Preparation

Using commercial muriatic acid can be dangerous! Wear gloves to prepare your solution. Mix your solution in pyrex glassware and under a fume hood if possible. Measure 300 mL of water (preferably distilled). Slowly and carefully add 75-100 mL of concentrated muriatic acid. The mixture will get HOT. Your may need to put it in a cold water bath until dissolving is complete.

 

Safety Precautions

1. Proper eye protection should be used.
2. Hydrochloric acid is corrosive. Proper care should be used to protect skin and clothing.
3. If you are using glass bottles or jars, the containers should be wrapped with a cloth.
4. Hydrogen gas is explosive! Do not have open flames or sparks near gas production or storage area.