Hydrogen and Oxygen Gas: An Explosive Interaction
Initial Publication Date: August 2, 2009
Summary
This lab provides the opportunity for students to generate, collect, and test two very common gases, hydrogen and oxygen. They will qualitatively test the combustion reaction of different proportions of the gases based on the audible outcome (loudest) being most reactive. Students create a bar graph to represent their observations of each of the proportions, including pure hydrogen and pure oxygen, in a logical fashion. Students finish the lab with a question sheet which allows them to apply concepts from classroom lecture to the lab activity.
CollapseLearning Goals
Students will develop an understanding of chemical proportions used in reactions and how the amount of a reactants can influence the products.
Students will develop the concept of activation energy in chemical reactions.
Students will observe and create original representations of the data collected during the lab with special attention to logical reasoning. Both an organized data table will be created as well as a bar graph that represents the data collected.
Key concepts would include: 1) Understanding the chemical nature of a decomposition and single replacement reaction.
2) Begin to develop the concept of limiting reagents and excess reagents.
Vocabulary:
Single-replacement reaction
Decomposition reaction
Reactants
Products
Limiting reagent
Excess reagent
Students will develop the concept of activation energy in chemical reactions.
Students will observe and create original representations of the data collected during the lab with special attention to logical reasoning. Both an organized data table will be created as well as a bar graph that represents the data collected.
Key concepts would include: 1) Understanding the chemical nature of a decomposition and single replacement reaction.
2) Begin to develop the concept of limiting reagents and excess reagents.
Vocabulary:
Single-replacement reaction
Decomposition reaction
Reactants
Products
Limiting reagent
Excess reagent
Context for Use
I have limited experience with this activity as I am new to teaching chemistry. However, the single experience with a class in lab was very positive and will be used again in the future.
My chemistry class seemed well prepared for this lab with background understanding of the different types of chemical reactions. They also benefitted from a good understanding of stoichiometry. Students worked in groups of three during the activity. Students were to ensure every group member took at least one gas collection. The gas collection area was placed inside the fume hood during the lab. As always with wet labs, safety goggles must be worn at all times. We use a Bunsen burner for ignition, but a candle could be used as well. The lab falls in the middle of the academic year when the students have a good comfort level in the lab and the content background to hypothesize based on observations.
My chemistry class seemed well prepared for this lab with background understanding of the different types of chemical reactions. They also benefitted from a good understanding of stoichiometry. Students worked in groups of three during the activity. Students were to ensure every group member took at least one gas collection. The gas collection area was placed inside the fume hood during the lab. As always with wet labs, safety goggles must be worn at all times. We use a Bunsen burner for ignition, but a candle could be used as well. The lab falls in the middle of the academic year when the students have a good comfort level in the lab and the content background to hypothesize based on observations.
Description and Teaching Materials
Lab Procedure
Put goggles and apron on now.
Record all observations in your lab notebook, taking care to keep data organized and neat.
1) Fill a beaker (1000ml) 3/4 full with tap water. This will act as a test tube holder, a temperature regulator, and a water reserve during the experiment.
2) Using a graduated cylinder and a pen, mark 6 equal increments on a polyethylene pipet bulb which has had the pipet cut off leaving a short collection tube.
3)Light your Bunsen burner and adjust it to a medium-sized cool flame.
4) Using a test tube for a hydrogen generator, place several pieces of zinc metal in the test tube and top it with a single hole stopper with a nozzle. Make sure your nozzle and pipet bulb will couple adequately. To activate the hydrogen generator, add enough 1 M HCl to fill the test tube to within 2 cm of the top. Replace the stopper and set the generator in the beaker of water. Wait 5 seconds before beginning the next step.
5)Fill the collection bulb completely full of water, then place the end of the pipet over the end of the generator and collect the hydrogen gas.
6) Once the collection bulb has become filled with gas, hold it horizontally with its mouth roughly 1 cm from the mid-section of the flame. Avoid putting the bulb directly in the flame, it will melt and possible burn. Should this happen, simply quench the tip in the beaker of water and obtain a new bulb. Gently squeeze a very small portion of the contents of the bulb into the flame and observe.
7) Repeat steps 4-6, generating, collecting and testing oxygen this time. There are two important differences to keep in mind. First, the test tube labeled "Oxygen generator" does not contain zinc; it contains pieces of manganese metal with an oxide coating = manganese oxide. Secondly, hydrogen peroxide, not hydrochloric acid, will be added to the test tube.
8) With both gases being generated side by side, collect and test all different possible ratios of hydrogen and oxygen gas. Be as consistent as possible each time. If either of the reactions should slow down, limiting the amount of gas being produced, simply remove the stopper and carefully pour off the remaining liquid into the sink and replace it with the appropriate fresh solution.
9) Create a bar graph that shows in a logical fashion the relative loudness of each of the samples that you tested, including the pure hydrogen and pure oxygen.
10) Answer the post lab questions and turn in with a data table and bar graph.
Put goggles and apron on now.
Record all observations in your lab notebook, taking care to keep data organized and neat.
1) Fill a beaker (1000ml) 3/4 full with tap water. This will act as a test tube holder, a temperature regulator, and a water reserve during the experiment.
2) Using a graduated cylinder and a pen, mark 6 equal increments on a polyethylene pipet bulb which has had the pipet cut off leaving a short collection tube.
3)Light your Bunsen burner and adjust it to a medium-sized cool flame.
4) Using a test tube for a hydrogen generator, place several pieces of zinc metal in the test tube and top it with a single hole stopper with a nozzle. Make sure your nozzle and pipet bulb will couple adequately. To activate the hydrogen generator, add enough 1 M HCl to fill the test tube to within 2 cm of the top. Replace the stopper and set the generator in the beaker of water. Wait 5 seconds before beginning the next step.
5)Fill the collection bulb completely full of water, then place the end of the pipet over the end of the generator and collect the hydrogen gas.
6) Once the collection bulb has become filled with gas, hold it horizontally with its mouth roughly 1 cm from the mid-section of the flame. Avoid putting the bulb directly in the flame, it will melt and possible burn. Should this happen, simply quench the tip in the beaker of water and obtain a new bulb. Gently squeeze a very small portion of the contents of the bulb into the flame and observe.
7) Repeat steps 4-6, generating, collecting and testing oxygen this time. There are two important differences to keep in mind. First, the test tube labeled "Oxygen generator" does not contain zinc; it contains pieces of manganese metal with an oxide coating = manganese oxide. Secondly, hydrogen peroxide, not hydrochloric acid, will be added to the test tube.
8) With both gases being generated side by side, collect and test all different possible ratios of hydrogen and oxygen gas. Be as consistent as possible each time. If either of the reactions should slow down, limiting the amount of gas being produced, simply remove the stopper and carefully pour off the remaining liquid into the sink and replace it with the appropriate fresh solution.
9) Create a bar graph that shows in a logical fashion the relative loudness of each of the samples that you tested, including the pure hydrogen and pure oxygen.
10) Answer the post lab questions and turn in with a data table and bar graph.
Teaching Notes and Tips
This lab can be used as an introduction to hydrogen-oxygen rockets.(see lab in SERC) I have also shown large scale interactions of these two gases with clips from you-tube, or other chemistry resources, as I am not comfortable with the large scale demos. I always show these videos during the post lab discussion. I would make sure to demonstrate the technique of collecting the gas from the generators and igniting the gases as well.
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Assessment
Students will answer the questions on the handout during the lab to be turned in at the end of class. Students will also create and data table for their observations and a graph that represents the data collected.
Standards
9.2.1.2.3 - Describing chemical reactions with equations
9C.2.1.3.1 - Classification of chemical reactions
9C.2.1.2.4 - Balance equations by applying law of conservation of mass
9C.2.1.3.1 - Classification of chemical reactions
9C.2.1.2.4 - Balance equations by applying law of conservation of mass