Introduction: (Initial Observation)
Carbon dioxide is the byproduct of many chemical and biochemical reactions. Fossil base fuels and other organic material such as wood can burn and produce a large amount of carbon dioxide.
A solution of carbon dioxide in water also known as carbonated water is a weak acid called carbonic acid. Carbonic acid is corrosive for many metals, however it is also a good preservative for many food products. Since carbon dioxide exists in the air, it can naturally be absorbed by surface waters, rain or snow.
Because of the properties of carbon dioxide, it is important to know the solubility of carbon dioxide in water at different temperatures.
Soda manufacturers and bottling companies, inject carbon dioxide in many drinks including Coke, Pepsi and almost all others. They also want to know at what conditions the most amount of carbon dioxide will be absorbed by water. Without this knowledge, their product may come out flat, from the beginning.
We know carbonated water is the main ingredient of most soda drinks. Carbonated water is also sold in pure form (no sugar, flavor or dye added) as Seltzer and other brand names. However, we usually don’t know what percentage of such drinks is carbon dioxide.
Is it one percent? … Is it ten percent? … or maybe 65%? I have no idea.
I think it is important to know what percentage of soda or carbonated water is carbon dioxide. I like to know how much gas I am placing in my stomach when I drink soda.
Another thing that I like to know is what happens to water when it absorbs carbon dioxide? Does carbon dioxide increase the weight or volume of water? How much? Can we use such increase in weight or volume to determine how much carbon dioxide is absorbed by certain amount of water?
In this project we deal with carbon dioxide solution as a weak acid and measure it’s amount by neutralizing that using sodium hydroxide. The same method can be used to find more information about carbon dioxide such as it’s molecular volume.
Learn about carbon dioxide and its properties. Find out how does the temperature affect the solubility of different substances in water. Read books, magazines or ask professionals who might know in order to learn about the effect of temperature on the solubility of gases or solids in water. Keep track of where you got your information from.
If you search the Internet for CO2 uses (or applications), you may find information such as:
Carbon dioxide used to clean radioactive soil
Carbon dioxide can be used to clean soil contaminated by past nuclear weapons development and nuclear energy research, using the same technique for decaffeinating coffee and dry cleaning clothes, new research has revealed.
Carbon Dioxide is also used for fire fighting, as a refrigerant, in carbonated beverages, to help vegetables grow quicker in greenhouses, and to flush oil wells. Solid carbon dioxide is known as Dry Ice.
Source: Project Advisor
Carbon Dioxide Applications
Food and Beverage…Carbon dioxide is used in beverage carbonation. A natural anti-microbial, carbon dioxide is also used to increase the shelf life of dairy products, protecting taste and texture, and reducing the need for preservatives, natural and artificial. Other applications include: food freezing and chilling, packaging, mixer and blender cooling, ingredient cooling and conveying, and in-transit refrigeration. In its solid form, it is known as dry ice. Many people know carbon dioxide is used in food freezing, carbonated beverages and dry ice. But most don’t realize it also helps to clear the air, clean the water and save the trees.
Water Treatment…Industrial and municipal wastewater must be neutralized before being discharged to the environment. Carbon dioxide replaces harsher acids for the alkaline neutralization process. It’s safer and cheaper than sulfuric-acid systems, improves controllability, and there’s less downtime and no labor to handle chemicals. It also is less corrosive, and easier to handle and store.
Metal Fabrication…Commonly utilized as a shielding gas during welding. This prevents atmospheric contamination of molten weld metal during gas shielded electric arc welding process.
Plant Growth…Carbon dioxide systems greatly improve growth and quality of plants in the greenhouse. Increasing concentrations of the gas results in larger, healthier and faster-growing plants and lower operating costs, especially during the winter, when it can reduce heating costs by 50%. Carbon dioxide replaces gas generators, saving fuel costs and eliminating harmful emissions.
Pulp and Paper…Carbon dioxide is being used for several different applications within paper mills, all developed to reduce costs and recover valuable chemicals used within the mill process. A process using carbon dioxide, instead of sulfuric acid, to treat pitch build-up in screen rooms is proving very successful.
Saving the Forest…Carbon dioxide is used to make precipitated calcium carbonate (PCC), which is used to reduce the use of virgin wood fiber in paper making. Applications include: supply of carbon dioxide for on-site PCC production and in-situ formation of PCC during the paper-making process.
Energy Source…Storage of carbon dioxide at its triple point (the temperature-pressure combination at which carbon dioxide can exist simultaneously as a solid, liquid or gas) is being tested as a means of providing closed-loop refrigeration in order to shift electrical-energy demand to off-peak consumption hours. Under test in Japan, the process offers the potential to customers to shift electrical load while maintaining temperatures as low as minus 60°F (-51°C).
Cleaning and Solvent Extraction…In its supercritical state (87.9°F (31.1°C) and 1070.6 psia (7.38MPa)), carbon dioxide becomes a versatile solvent. It can replace chlorinated fluorocarbons to clean equipment components. It also can replace many volatile organic chemicals for operations such as decaffeinating coffee or extracting fat from food products.
Fire Fighting…Carbon dioxide smothers fires without damaging or contaminating materials and is used for fighting fires when water is ineffective, undesirable or unavailable.
Dry Ice Applications
Dry Ice will keep perishable items frozen longer and fresher with out all the hassle and mess of traditional ice. It’s perfect for shipping, picnics or camping trips. And Dry Ice is the only form of ice that can keep ice cream frozen.
Special Effect “Fog” for Parties
Haunted Houses “Witches Brew” Punch Jack-O-Lanterns Pool/Jacuzzi Parties
Making Baking Soda Volcanoes Cloud Chambers School Carnivals/Fun House
Car Dent Removal
Hold a little Dry Ice on a small car dent and it will reduce the dent without
chipping or cracking the paint.
Adding Dry Ice (C02) to a non-carbonated drink will give it bubbles and make it cold.
Keep Mosquitoes Away
Place a block of Dry Ice in your yard and mosquitoes will be attracted to it,
instead of you and your guests.
The gas that Dry Ice creates (C02) is heavier than air so it will find its way to
the bottom of gopher nests.
Retard Bacteria Growth
Adding Dry Ice snow during hamburger and sausage preparation reduces the meat’s temperature rapidly, which retards bacteria growth.
What is titration?
Titration is a standard laboratory method of chemical analysis which can be used to determine the concentration of a known reactant.
Titration is the quantitative measurement of an analyte in solution by completely reacting it with a reagent solution. The reagent is called the titrant and must either be prepared from a primary standard or be standardized versus a primary standard to know its exact concentration.
The point at which all of the analyte is consumed is the equivalence point. The number of moles of analyte is calculated from the volume of reagent that is required to react with all of the analyte, the titrant concentration, and the reaction stoichiometry.
The endpoint (equivalence point) is often determined by visual indicators are available for titrations based on acid-base neutralization, complexation, and redox reactions. and is determined by some type of indicator that is also present in the solution. For acid-base titrations, indicators are available that change color when the pH changes. When all of the analyte is neutralized, further addition of the titrant causes the pH of the solution to change causing the color of the indicator to change.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to determine the solubility of carbon dioxide in water at various temperatures.
We also try to determine the molar volume of carbon dioxide.
By making measurements on a sample of carbon dioxide, you are able to determine the molar volume of CO2. Molecular weight of carbon dioxide is 44. You must find out what is the volume of 44 grams of CO2 while in water.
Where did you get 44 from?
Molecular weight is the sum of atomic weight of all atoms in one molecule. CO2 has one carbon with atomic weight of 12 and two oxygen with atomic weights of 16 each. So the molecular weight of CO2 is 12+16+16=44
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
The independent variable (manipulated variable) is the temperature.
The dependent variable (responding variable) is the solubility of CO2 in water.
Controlled variables are all other factors that may affect the result of our experiment and we need to monitor and control them. Some of our controlled variables are light, type of water used for experiment and experiment method and procedures.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. This is a sample hypothesis:
I think solubility of carbon dioxide in water will increase in higher temperatures. My hypothesis is based on my observation of using heat to dissolve salts, sugar and other material in water. In all these cases heat will accelerate dissolving process and increase the rate of solute in solution.
Note that hypothesis must be testable and may be proven wrong by your experiments. Another possible hypothesis is:
The solubility of carbon dioxide in water increases by lowering the temperature. My hypothesis is based on my observation of dissolving other gasses (such as ammonia and hydrochloric acid) in water. For these gases solubility is more in lower temperatures. So I think solubility of all gasses in water decreases by increasing the temperature.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment 1: The solubility of carbon dioxide in water at various temperatures.
Introduction: In this experiment, you use carbonated water samples at various temperatures to determine how does the solubility of carbon dioxide in water vary with temperature. The acid, formed when carbon dioxide reacts with water, is titrated with sodium hydroxide solution to a phenolphthalein endpoint.
Since carbonated water is an acidic solution, we can titrate it with a known solution of sodium hydroxide and see how much sodium hydroxide does it take to neutralize the solution; From the amount of sodium hydroxide we can calculate the amount of CO2. For calculations you will use the reaction formula of sodium hydroxide and carbonic acid:
H2CO3 + 2 NaOH ===> Na2CO3 + 2H2O
62 grams + 80 grams ===> 106 grams + 32 grams
Phenolphthalein is an organic compound (C20H14O4) used as an acid-base indicator. The compound is colorless in acidic solution and pinkish in basic solution
- Keep a bottle of carbonated water in refrigerator for at least 6 hours.
- Get 3 clean 250 ml beakers or any similar containers for your samples.
- Add about 150 ml of cold carbonated water in each beaker.
- Place one beaker in the refrigerator. Allow one beaker to stand at room temperature and place the other in a warm water bath.
- Let the samples stay at this conditions for at least 30 minutes before starting your experiment.
Use the following procedure to test samples for their CO2 contents.
- Measure out 50 mL of any sample and transfer to an Erlenmeyer flask. Add 3 drops phenolphthalein solution and swirl gently for one minute to remove any remaining mechanically trapped carbon dioxide.
- Using a dropper, titrate with 2.0 M NaOH solution until the pink phenolphthalein color persists for 30 seconds. Record the number of drops of NaOH solution used.
- Repeat steps 1 and 2 using samples at different temperatures.
- Multiple samples may be titrated if time permits.
- Plot a graph of drops of NaOH solution required for neutralization vs. temperature and draw conclusion about how the solubility of carbon dioxide varies with temperature. (Note that more carbon dioxide gets more NaOH to nutralize; so, the amount of CO2 has a relation with the amount of NaOH)
Titrated samples may be disposed of by flushing down the drain with running water.
The NaOH solution is caustic; avoid contact with skin. Goggles must be worn throughout the experiment.
Note 1: 2.0 M NaOH solution is an 80 grams per Liter Solution. You can also call it a 2 normal solution. (Normal solution is 40 grams/Liter solution)
Note 2: If you have access to a pH meter, you will not need phenolphthalein. You can titrate the solution until you get to pH = 9. (pH=9 is the expected pH of resulting sodium carbonate solution)
Note 3: If you have a pipette or burette, you don’t have to count the drops, you can use the number of milliliters of NaOH used instead.
Your results table may look like this:Titrated samples may be disposed of by flushing down the drain with running water.
|Temperature||Drops of NaOH used to neutralize CO2|
|110ºF (Warm water)|
Make a graph:
Use the above results table to make a bar graph that can visually present your results. Make one vertical bar for each temperature you test. Under each bar write the temperature it represents. The height of each bar will show the number of NaOH drops used to neutralize the CO2.
Experiment 2: What is the concentration of CO2 in carbonated water? determine the molar volume of carbon dioxide.
In this experiment you measure the amount of CO2 in a sample of carbonated water. You will then use your measurement to calculate the molecular volume of CO2.
- Mass an empty clean Erlenmeyer flask.
- Measure out 100 ml of carbonated water in the Erlenmeyer Flask.
- Mass the Flask with it’s content and calculate the mass of 100ml of carbonated water.
- Using a burette or pipette, titrate with 2.0 M NaOH solution until the pink phenolphthalein color persists for 30 seconds. Or until the pH becomes 9 and remains 9 for 30 seconds.
- Record your data in a table like this:
|Sample Volume||100 ml|
|Volume of 0.2 M NaOH used to neutralize||?? ml|
Use your data to calculate the amount of CO2 in your sample and the molecular volume of CO2. See the calculations section for more details.
How can I simplify the experiment number 1? I want to compare the solubility of carbon dioxide in water at various temperatures. Is there a simple way to do that?
This is the simple method I suggest:
When the solubility is less, more gas will release. For your experiment open a 2-liter bottle of cold carbonated water and transfer the content to 3 identical small bottles. Place a balloon on top of each bottle and secure the balloon to the neck of bottle with some strings and a knot (rubber band may work too). Place one bottle in cold place, one in room temperature and one in a warm place. See which balloon inflates more. The larger the balloon inflates, the lower the solubility is.
Materials and Equipment:
- Carbonated water (Seltzer, club soda)
- 2.0 M NaOH solution (80 g NaOH dissolved in enough distilled or deionized water to make 1.0 liter of solution)*
- phenolphthalein solution (1% in ethanol)*
- 1-L beakers*
- ice bath and warm water bath – large enough to hold a 1-L beaker
- 100-mL graduated cylinders
- 200-mL Erlenmeyer flasks
- eye dropper or Pasteur pipette*
- Sodium hydroxide is available as lye in grocery stores. It is also available in hardware stores as drain opener. It is while flakes or granules.
- Phenolphthalein indicator solution may be purchased from ChemicalStore.com using the product code PHPH1, or you may buy it in powder form using the product code PHPH and make your own alcohol based solution.
- Any large jar or other container could be substituted for the 1-L beakers.
Results of Experiment (Observation):
Carbonated beverages are bottled under a carbon dioxide pressure slightly greater than 1 atmosphere. When the bottles are opened to the air, the partial pressure of CO2 above the solution is decreased and CO 2 bubbles out of the solution. The bottles should be cold when opened because CO2 is most soluble at low temperatures. Bottles should be opened prior to doing the experiment to allow the dissolved CO2 to reach equilibrium with the lower pressure of CO2 in the air. Preparing the samples early also allows each sample to reach temperature equilibrium. When carbon dioxide dissolves in water it reacts with water to form an acidic solution which can be neutralized by the addition of base.
CO2 (aq) + H2O (l) <====> H+(aq) + HCO3-(aq) [sometimes written as H2CO3 (aq)]
Results obtained by this procedure are intended to indicate a trend in the solubility of the carbon dioxide as a function of temperature. They will not agree with literature values for the solubility of carbon dioxide which are usually measured at higher partial pressures of the gas.
For the experiment number 2, you will need to do some calculations.
The first calculation is to determine the actual amount of NaOH used to neutralize the carbonated water. Since you have used 2.0 M solution of NaOH, each 1000 ml of your solution contains 80 grams of NaOH. So if you know how many milliliter of NaOH you have used, you can multiply that by 0.08 to find out how many grams of NaOH has been used.
After you know the amount of NaOH used to neutralize the solution, you will then use the reaction formula of neutralization to calculate the amount of H2CO3 neutralized. The reaction formula is:
H2CO3 + 2 NaOH ===> Na2CO3 + 2H2O
62 + 2 x 40 ===> 106 + 2 x 18
This formula shows that every 80 grams of NaOH can neutralize 62 grams of carbonic acid. So by knowing the amount of NaOH, you can calculate the amount of carbonic acid.
Since carbonic acid can break down to one molecule water and one molecule CO2, each 62 grams of carbonic acid is equivalent to 18 grams of water and 44 grams of CO2. You use these numbers to calculate the amount of CO2 (by weight).
When you have the weight of CO2, you can subtract it from the total weight of solution to determine the weight of water.
When you have the weight of water, you also know the volume of water. (because the density or specific gravity of water is 1, so for example the mass of 70 ml of water is 70 grams.)
Subtract the volume of water from the total volume (100 ml) to determine the volume of CO2.
Divide the weight of CO2 by the volume of CO2 to determine it’s density.
Or with a simple ratio calculate the volume of 44 grams of CO2. That will be the molecular volume of CO2 when absorbed in water.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Although the procedure is rather straight forward, it is necessary to be careful to provide samples that vary only in their temperature and that students use reproducible methods in doing the experiment. Best results are obtained when the dropper is held vertically while titrating.
Brown, T.L. and LeMay, H.E., Jr., Chemistry – The Central Science, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1981. Chaps. 12, 15, and 17 discuss the chemistry of solutions of carbon dioxide in water.
Gordon, G. and Keifer, The Delicate Balance, Harper & Row, Publishers, New York, 1980, pp. 110-111. In an experiment described here, bottles of Seltzer water maintained at three temperatures are opened and the acid (from dissolved CO 2) is titrated using burettes.
Sample solubility results: (Not verified)
|Temperature in Celsius degrees||weight of gas in g/100 g water|
Sample solubility graph: (Not verified for accuracy)