Making Micro-Hindenburgs

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					                                     Making Micro-Hindenburgs
Introduction
         The Hindenburg was the largest airship ever built. It had a record of 54 successful flights. However, what
people remember most about the Hindenburg is its tragic end at Lakehurst, New Jersey. On May 6, 1937, the
hydrogen-filled Hindenburg burst into flames as the pilot was attempting to land it. Thirty-six people were killed while
horrified onlookers watched. The exact cause of the explosion has never been determined, but the Hindenburg
disaster essentially ended wide-scale development and use of airships.
         Why was the Hindenburg filled with hydrogen? Would another gas have been better? In this lab you will
make hydrogen gas and investigate its properties so that you can answer these questions.

Pre-Lab Questions
Read the entire procedure and relevant pages in your textbook, then answer the following questions.
1. Find hydrogen in the periodic table and explain why it is separated from the Group 1A.
2. What chemicals are used to produce hydrogen gas in this lab?
3. Why should you handle hydrochloric acid (HCl) with care?
4. What should you do if you accidentally spill some HCl?
5. What is the purpose of the bubble solution?
6. What do you predict will happen when you hold the flame near the bubble of gas produced in this investigation?
On what information is your prediction based on?

Problem
What properties of hydrogen prevent its use in modern-day airships?

Materials
chemical splash goggles; test tube; test-tube rack; hydrochloric acid (HCl), 3.0 M
scissors; micropipette; solution bubble; one-hole rubber stopper; matches; granulated zinc

Safety
Wear your goggles, at all times during the investigation. Hydrochloric acid is corrosive. If you spill any acid,
immediately wash the area with plenty of cold water and notify your teacher. Tie back loose hair and clothing when
working with a flame.

Procedure
1. Put on goggles, gloves, and lab apron.
2. Make a microfunnel, using the scissors to cut off the top of the plastic
    micropipet bulb.
3. Insert the microfunnel into the one-hole rubber stopper as shown and
    set aside.
4. Place about 1g of granulated zinc in the test tube. Place the test tube in
    the test tube rack. Then carefully pour 5 mL of 3.0 M hydrochloric acid
    (HCl) into the test tube.
CAUTION: Hydrochloric acid is corrosive. Avoid spills and splashes. If you
do spill acid, immediately rinse the area with plenty of cold water and report
the spill to your teacher.
5. Record your observations.
6. Insert the rubber stopper with the microfunnel into the test tube so that no gas
    can escape except by way of the microfunnel. With a micropipet provided by
    your teacher, place 5-10 drops of bubble solution into the microfunnel, as shown
    in Figure 18-2.
7. Record your observations.
8. Light the match. CAUTION: Tie back loose hair and clothing when working with
    the flame. Carefully bring the flame close to the bubbles rising from the
    microfunnel.
9. Record your observations. (If generation of gas slows or ceases, extinguish the
    flame. Remove the stopper and add more zinc and HCl. Then reinsert the micro
    funnel and stopper, relight the splint, and test the bubbles.)
10. Disassemble the apparatus and dispose of the reaction products in a container provided by your teacher.
    CAUTION: The product in the test tube, zinc chloride (ZnCl2), is a severe skin irritant. Avoid direct contact. If
    spills occur, wash the area with plenty of water.
11. Clean up your work area and wash your hands before leaving the laboratory.

Observations
zinc with hydrochloric acid                             ____________________________
bubble solution in microfunnel                        ____________________________
flame held near bubbles                              ______________________________

Post-Lab Questions
1. What evidence in this investigation suggests that a chemical reaction has occurred?
2. Based upon your data, what properties of hydrogen are demonstrated in this Investigation? (Hint: Why did the
   bubbles float in the air?)
3. What purpose did the bubble solution serve?
4. Since the German zeppelin Hindenburg filled with hydrogen gas was destroyed in a violent fire:
        a. Write a balanced chemical reaction for the combustion of hydrogen.
        b. Is this reaction exothermic or endothermic?
5. Though more dangerous, a given volume of hydrogen gas will lift more weight than an equal volume of helium.
This is because hydrogen is less dense than helium. Use Avogadro’s hypothesis to explain why hydrogen is less
dense than helium.
6. Why do you think that hydrogen was used to fill the Hindenburg?
7. Modern airships are filled with helium. Unlike hydrogen, helium does not burn. Use your knowledge of valence
electron configurations to explain why helium is safer than hydrogen for use in airships.
8. Balloons are usually filled with simple hot air instead of helium. Use the ideal gas law to explain why a hot air
balloon floats.
9. What other gas would have been a better choice than hydrogen to fill the Hindenburg?
10. Why do you think that this investigation is entitled “Making Micro-Hindenburgs”?
11. Why would it be dangerous to do this investigation on a larger scale?

				
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