Micro Mole Rockets
Advanced Chemistry Lab #2
Rachel Metzler
September 24, 2010
Purpose: The purpose of this lab is to determine the most explosive, or reactive
combination of oxygen and hydrogen that produces water. Then through this
combination, or ratio, calculate the mole ratio for the reaction of hydrogen and
oxygen in a balanced equation.
Procedure: Calibrate gas collection bulbs. Collect hydrogen and oxygen gasses from
the reactions of HCl with zinc (hydrogen) and H2O2 with yeast (oxygen). Then repeat
process for each different ratio of hydrogen and oxygen gas mixture, testing each
with a match-pop test.
Pre-Lab Questions:
1. Write the balanced chemical equation for the single-replacement reaction of
zinc and hydrochloric acid to generate hydrogen gas.
Zn + 2HCl  ZnCl2 + H2
2. Write the balanced chemical equation for the yeast-catalyzed decomposition
of hydrogen peroxide to generate oxygen gas and water. Note: Since a
catalyst is not really a reactant or product, it is usually written over the arrow.
H2O2  O2 +H2
Results:
Observations: The mossy zinc is black and gray, and with mixture of the HCl
it bubbles, circulating little bits of black in the solution and producing lots of
bubbles(of hydrogen). The yeast solution is tan or light brown in color and with
H2O2 the solution bubbles. The gases produced are clear as well.
Data:
“Pop-test” Properties of H2 Gas
“Pop-test” Properties of O2 Gas
Very mild pop noise (2)
None (0)
Pop-test Properties of O2:H2 Gas Mixtures
Oxygen: Hydrogen Mole Ratio
1:5
2:4
3:3
4:2
5:1
Relative Loudness
10
8
5
3
0
1
Calculations: None.
Conclusion: Through this experiment it can be concluded that hydrogen and
oxygen in a five to one ratio, respectively, creates the loudest popping noise.
Discussion of Theory: Testing the ratios of hydrogen to oxygen allowed us to use
the concept of mole ratios and limiting reactants in order to find the mole ratio of a
hydrogen and oxygen reaction.
Experimental Sources of Error: One source of error would be the tester bulbs.
Their markings were not all exactly the same and after use the markings rubbed off
slightly, leaving it harder to get exact measurements. This source of error could have
affected the amounts of gas in each one, skewing the data.
Post Lab Questions: (Answer any questions included in the lab. Answer in such a way
that the meaning of the question is obvious in your answer. )
1. Draw a bar graph to illustrate the relative loudness produced by pop-testing
various oxygen/hydrogen gas mixtures.
Relative Loudness
10
8
6
4
2
0
Relative
Loudness
1:5 2:4 3:3 4:2 5:1
Oxygen:Hydrogen Ratio
2. The relative loudness of pure oxygen was a zero, and for hydrogen was a two
in the pop test
3. The balanced chemical equation for the combustion reaction of hydrogen and
oxygen to give water is: 2H2 + O2  2H2O
4. Complete the following sentence to describe the number of moles of each
reactant involved in the combustion of hydrogen: ____4____ moles of hydrogen
react with ___2___ moles of oxygen to give ____2____ moles of water.
When the reactants in a mixture are present in the exact mole ratio given by the
balanced chemical equation, all of the reactants should be used up when the
reaction is over. There will be no “leftover” reactants. However, if one of the
reactants is present in an amount greater than its mole ratio, then that reactant
cannot react completely, and some of it will be left over at the end of the reaction.
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5. Use the mole ratio of hydrogen to oxygen from Question #4 to determine
what happens when various hydrogen/oxygen gas mixtures are allowed to
burn. Complete the following table to indicate which reactant (H2 or O2) is
present in excess, and how much of it will be left over after the combustion
reaction is complete. Note: The second one has been completed as an example.
Parts H2
Parts O2
Which reactant is present in
excess?
How much of that reactant is left
over?
6
0
H2
5
1
H2
4
3
2
3
None O2
2
4
O2
1
5
O2
0
6
O2
6
3
n/a
3
4.5
6
1.5
6. Which oxygen/hydrogen gas mixture produced the most explosive mixture?
Explain why this mixture was most explosive.
The 1:5 ratio of oxygen to hydrogen gas mixture was the loudest.
7. Why do the hydrogen and oxygen gas mixtures in the collection bulb not
react as soon as they are collected? Note: Consider the role of the match and
the properties of gas molecules at room temperature.
The gas mixtures do not react as soon as they are collected because it takes
time for them to fully mix at room temperature. The match heats the gas
molecules and so they react quickly.
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