if oxygen is removed from a sample of air as iron rusts what happens to the partial pressure of air

From Gas to Rust: Measuring the Oxygen Content of Air

Abstract

World's atmosphere, the bounding main of air that blankets the planet, is more often than not nitrogen and oxygen, with small amounts of other gases. How much oxygen is present in air at sea level? In air loftier upwards in the Appalachians or Rockies? Atop Mountain Everest? How much oxygen is present in the air you breathe? Hither'due south a project that shows you how to measure out the percentage of oxygen in an air sample.

Summary

Average (6-ten days)

None

Readily available

Low ($20 - $50)

No problems

Objective

Measure the percentage of oxygen in air samples.

Introduction

We alive most the lesser of an sea of air that surrounds the earth. The atmosphere protects us from harmful radiation from the dominicus, all the same captures plenty of the sunday's light and warmth to make the planet habitable. Speaking of habitable, the atmosphere likewise contains the oxygen we need to exhale to back up cellular respiration, the metabolic process that provides the chemical energy necessary for life.

How much oxygen is in the air? This projection will testify you an interesting way to measure out the percentage of oxygen in a sample of air in a test tube. The method depends on atmospheric force per unit area and a chemical reaction that removes oxygen from the air.

And so what kind of chemical reaction can remove oxygen from the air? Oxidation of iron, also known as rusting, will do the trick. Exposed atomic number 26 will rust in the presence of oxygen and water. As y'all do your groundwork research, study this chemic reaction, and you will run into that oxygen becomes combined with the iron atoms and water to create iron oxides.

You'll use plain, fine steel wool (bachelor at the hardware store) as your source of iron, placing it in the lesser of a test tube. Then, yous'll dampen the steel wool, plow the test tube upside down, and mount information technology and so that the rima oris is submerged under water. This will trap the air in the exam tube and also provide water vapor for the oxidation reaction. You will have all of the chemicals necessary for the reaction: iron in the steel wool, plus oxygen and h2o vapor in the air in the test tube. Every bit the iron rusts, oxygen is removed from the air sample in the test tube. With less gas, there volition be lower pressure level inside the exam tube (fewer gas molecules bouncing around, pushing on the walls of the test tube and the surface of the water inside the tube). Meanwhile, your experiment will continue to be under the (more or less) constant pressure level of the ocean of air, atmospheric pressure. And then what will happen to the h2o level in the test tube equally the oxygen in the air sample becomes sequestered in iron oxide?

That's how you'll measure out the percentage of oxygen in your air sample. By measuring the h2o level at the start of the experiment, and at the cease (when the h2o level has stopped irresolute), you can take the divergence to find out how much oxygen was used to oxidize the steel wool.

How does oxygen content change with altitude? Can you lot use this method to find out?

Terms and Concepts

To do this project, you should do research that enables you to understand the following terms and concepts:

Temper
Oxygen
Atmospheric pressure
Oxidation
Rusting

Questions

What are the gases that comprise Earth'south temper?
What chemical reaction occurs when fe rusts?
Why does the water level in the exam tube rise as the steel wool oxidizes?
Why does the h2o level somewhen stop ascension?
What would happen if a larger piece of steel wool was used? A much smaller piece?

Bibliography

This NASA website has data about atmospheric pressure:

Sample, S. (2003). It's a Cakewalk: How Air Pressure Affects You. Retrieved July 13, 2011.

These websites have information about the atmosphere:

Sharp, Tim. (2017, Oct 13). Earth'due south Atmosphere:Composition, Climate & Atmospheric condition. Infinite.com. Retrieved March three, 2021.
Cirjak, Antonia. (2020, May ane). What Are The 5 Layers Of The Earth's Temper?. Worldatlas.com. Retrieved March 3, 2021.

This website has information about rusting:

Wikipedia Contributors (2011, June xxx). Rust. Retrieved July thirteen, 2011.

Materials and Equipment

Examination tubes (6), all the same size; available from online suppliers such every bit Carolina Biological Supply Company.
Masking tape
Permanent marking
Jars or bottles (half-dozen); clean, clear, and each with the same height. You lot may detect suitable jars around your home, or they are bachelor from online suppliers such as Carolina Biological Supply Company
Band stands with clamps (half-dozen). Ring stands and clamps are available from Carolina Biological Supply Company.
- Alternative: if you cannot borrow these from school, yous can make your own device to hold the test tubes over the jars. Encounter Figures 2 and three for more details.
Steel wool (1 pad). Steel wool is bachelor from most grocery stores or from online suppliers such every bit Carolina Biological Supply Company.

Disclaimer: Science Buddies participates in affiliate programs with Home Science Tools, Amazon.com, Carolina Biological, and Jameco Electronics. Proceeds from the chapter programs help back up Science Buddies, a 501(c)(3) public charity, and keep our resources free for anybody. Our top priority is student learning. If you have any comments (positive or negative) related to purchases you've made for science projects from recommendations on our site, delight let us know. Write to us at scibuddy@sciencebuddies.org.

Experimental Process

Get your six ring stands ready. When the experiment is running, each of the half dozen ring stands will wait like the experimental setup in Figure 1.
1. If you practice not have access to six ring stands, yous can make your ain test tube holder. Figure 2 shows a schematic for a homemade examination tube holder. The photos in Figure iii bear witness an example of a homemade test tube holder constructed out of PVC pipe and rubber bands.

Fill all half dozen jars with h2o and then that they are nearly full. Information technology may be helpful to use a measuring cup to brand sure that each jar has exactly the aforementioned amount of h2o.
Attach a vertical strip of masking tape to the side of each of your test tubes (for mark the h2o level).
Using permanent marker, make a marking on the tape about one cm downwardly from the oral cavity of the test tube. This will be the outside water level.
Tear off plenty steel wool to make a ball about 2.five cm in diameter. Apply a pencil to push the steel wool down to the bottom of a test tube. Repeat for a total of three test tubes with steel wool.
Rinse all of the test tubes (iii with steel wool and three without) past filling the test tubes with water, allowing the water to sit down there for one minute, and then pouring the h2o out.
1. This footstep will dampen the steel wool in the iii tubes that have it thus making sure in that location is enough water present for the oxidation reaction.
2. Treating the iii test tubes without steel wool the same fashion ensures that all variables are controlled.
Turn all half dozen of the test tubes (iii with steel wool and three without) upside down and mountain them over the jars so that the h2o level is at the starting marking you made in step 3 on each exam tube.
You may want to cover your unabridged setup with a large plastic bag to minimize evaporation. Be careful non to knock the test tubes when covering and uncovering.
Check at to the lowest degree daily, and write your observations down in your lab notebook. Advisedly mark the water level on the tape on each test tube.
When the water level is no longer irresolute in the test tubes, you're ready to analyze your results.
Measure out the deviation in water level between the open finish of the test tube and the water acme inside the examination tube at the end of the experiment. For how many tubes did the water level modify? For those that did:
1. Calculate the book that corresponds to this departure. Use the formula for the volume of a cylinder, Equation 1, to approximate the book.
  Equation 1.
  Volume of a cylinder = π × r² × h
  - 5 is the volume in cubic centimeters (cm³)
  - π is the constant pi
  - r is the radius of the cylinder (cm)
  - h is the superlative of the cylinder (cm)

1. Calculate the total starting book of air in each test tube.
  - Remember, for tubes containing steel wool, the wool volition readapt near of the air. Make sure your measurements and calculations accept this in to account.
2. Calculate the proportion of oxygen in each test tube.
Boilerplate the proportion of oxygen from all the test tubes with steel wool. How does this compare with the value(s) for pct of oxygen in the air that you found in your background inquiry?
1. What are the potential sources of error in your measurement?

Enquire an Expert

Exercise yous take specific questions well-nigh your science projection? Our team of volunteer scientists can help. Our Experts won't do the work for you lot, but they volition make suggestions, offer guidance, and assistance you troubleshoot.

Variations

If y'all ever take a vacation in the mountains, you can use this method to compare oxygen levels in the air at high and low distance. Try doing this experiment at loftier altitude and comparison the results with same experiment done at a lower distance.
Can you apply this procedure to discover decreased oxygen content in exhaled air? Exercise groundwork research and find out how much oxygen nosotros consume when we exhale. Do you think this method is sensitive enough to find the departure? Design an experiment to find out.
What exercise yous think would happen if y'all collected air samples at loftier distance, and and then tested them at low altitude (or vice versa)? How easily does oxygen dissolve in water? Could dissolved oxygen affect your results? Design an experiment to observe out.

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MLA Style

Scientific discipline Buddies Staff. "From Gas to Rust: Measuring the Oxygen Content of Air." Science Buddies, iv Mar. 2021, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Weather_p004/weather-temper/oxygen-content-of-air-rust. Accessed eight April. 2022.

APA Manner

Scientific discipline Buddies Staff. (2021, March iv). From Gas to Rust: Measuring the Oxygen Content of Air. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Weather_p004/conditions-atmosphere/oxygen-content-of-air-rust

Last edit engagement: 2021-03-04

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