What is Carbon dioxide: Definition and 79 Discussions

Carbon dioxide (chemical formula CO2) is an acidic colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmosphere as a trace gas. The current concentration is about 0.04% (412 ppm) by volume, having risen from pre-industrial levels of 280 ppm. Natural sources include volcanoes, hot springs and geysers, and it is freed from carbonate rocks by dissolution in water and acids. Because carbon dioxide is soluble in water, it occurs naturally in groundwater, rivers and lakes, ice caps, glaciers and seawater. It is present in deposits of petroleum and natural gas. Carbon dioxide has a sharp and acidic odor and generates the taste of soda water in the mouth. However, at normally encountered concentrations it is odorless.As the source of available carbon in the carbon cycle, atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena. Plants, algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water, with oxygen produced as a waste product. CO2 is produced by all aerobic organisms when they metabolize organic compounds to produce energy by respiration. For instance, plants use it to produce carbohydrates in a process called photosynthesis. Since humans and animals depend on plants for food, photosynthesis, and therefore CO2, is necessary for the survival of life on earth.
It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals, including humans. Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread, beer and wine making. It is produced by combustion of wood, peat and other organic materials and fossil fuels such as coal, petroleum and natural gas. It is an unwanted byproduct in many large scale oxidation processes, for example, in the production of acrylic acid (over 5 million tons/year).It is a versatile industrial material, used, for example, as an inert gas in welding and fire extinguishers, as a pressurizing gas in air guns and oil recovery, as a chemical feedstock and as a supercritical fluid solvent in decaffeination of coffee and supercritical drying. It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence. The frozen solid form of CO2, known as dry ice is used as a refrigerant and as an abrasive in dry-ice blasting. It is a feedstock for the synthesis of fuels and chemicals.Carbon dioxide is the most significant long-lived greenhouse gas in Earth's atmosphere. Since the Industrial Revolution anthropogenic emissions – primarily from use of fossil fuels and deforestation – have rapidly increased its concentration in the atmosphere, leading to global warming. Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid.

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  1. B

    Will charcoal (carbon) oxidize in the air?

    Wikipedia — Carbon sequestration claims that burying charcoal into the soil offsets CO2 and thus reduces the greenhouse effect: Is it a must to cover charcoal/biochar with the soil to prevent the air and rain water exposure to avoid oxidation, i.e. offset carbon dioxide? Would it otherwise...
  2. PainterGuy

    Shouldn't they use carbon dioxide monitors?

    Hi, In many places in the US the carbon monoxide monitors are mandatory to be installed inside residential places. Source: www.kidde.com/home-safety/en/us/co-safety/carbon-monoxide-alarm-faqs/ Source: https://www.health.ny.gov/publications/2826.pdf Source...
  3. K

    Producing Renewable Liquid Fuels from Atmospheric Carbon Dioxide

    The Sasol plants in South Africa are producing liquid fuels using coal and water as the source of energy and syngas, CO and H2. Some refineries are using natural gas as the starting fuel to produce liquid fuels. Both of these processes are not renewable. The US Navy has a process to extract CO2...
  4. N

    Pressure in a sealed vessel

    I have a sealed vessel, it is 200 ml, it contains 25 ml of water which is then saturated with CO2 (bubbled through at 0.3 l/min unitil pH drops, ~ 1 h) at rt. The vessel is then heated to 130 °C. I wish to calculate the final pressure of the system. Thus far I have calculated the volume of CO2...
  5. C

    Can wearing N95 mask make you inhale the exhaled carbon dioxide?

    1. Can wearing N95 mask make you inhale the exhaled carbon dioxide? 2. Does it only protect against dusts or also bacteria or viruses? N95 can protect against 3 micron or larger. What are the sizes of bacteria or viruses?
  6. Ygggdrasil

    Scientists engineer E. coli that eats carbon dioxide

    E. coli is one of the best studied and most widely used bacteria in biotechnology. This week, published in the journal Cell, researchers report having engineered the bacterium to be able to generate all of its carbon from CO2, opening the way toward using these bacteria for replacement of...
  7. G

    Negative carbon emissions to fight ocean acidification?

    The IPCC report strongly encouraged not only trying to get our carbon dioxide emissions down to fight climate change, but to go into negative emissions so as to draw the carbon dioxide out of the air (since it's too high as it is). Wouldn't that help to fight ocean acidification too? Because...
  8. S

    Mosquitoes attracted by carbon dioxide?

    It's commonly said that mosquitoes are attracted by carbon dioxide - so I'll guess that there's empirical evidence for that assertion. But is the mechanism for this known? What is the localized concentration of carbon dioxide around a person respiring at a normal rate? Do we know that it's...
  9. J

    What is the heat of combustion of 1 kg carbon dioxide w/ magnesium?

    I am trying to find out the heat of combustion of one kilogram of carbon dioxide with magnesium. I am looking for results for stochiometric conditions of these two reactants. I have found the following equation online 2 Mg(s) + CO2 ---> 2 MgO(s) + C(s) yields a standard enthalpy of --810.1...
  10. Auto-Didact

    News Scientists turn CO2 back into coal

    Climate rewind: Scientists turn carbon dioxide back into coal The article says that this process takes place using a liquid metal catalyst at room temperature and is both efficient and scalable. The rest of the article can be read over at phys.org (link in title). The published paper (open...
  11. Z

    Carbon dioxide in liquid and gaseous phases with liquid water

    What are the differences between carbon dioxide solubility (miscibility, reaction) in liquid water when in gaseous (<38 bar) and liquid (>38 bar) phase? The temperature in my experiments is usually between 0 and 5°C. The stirring speed is around 500 rpm. Is the solubility given apart from...
  12. prakhargupta3301

    Is this interpretation correct? (diagrams of Carbon Monoxide and Carbon Dioxide)

    *SORRY FOR BAD DIAGRAM* Is this correct for C(triple bond)O ie Carbon Monoxide This is for CO2. Please check both. ALso check everything ie hybridized orbitals, bondings etc. I'm trying to clear concepts. (Note: red= unhybridized, black= hybridized) Thank you.
  13. BillTre

    Sequestering Carbon Dioxide in Rock

    About possibly using peridotite to capture large amounts of CO2 out of the air. Nice pictures, very little chemistry. NY Times story here.
  14. A

    Alka seltzer in water question

    Hi everyone. I was testing the pH of water that had alka seltzer placed in it. I used Bromothymol blue indicator to see the pH. The color changed to yellow, which suggests that the water was now acidic. I assume this is because of the CO2 bubbles that form which can acidify the H2O. Am I...
  15. Mzzed

    Can carbon dioxide be broken down into carbon monoxide and oxygen?

    I have recently seen a paper ( https://www.nature.com/articles/nenergy201787 ) that describes a method to break down carbon dioxide into carbon monoxide and oxygen. I would love to know how they were able to come up with a method such as this but unfortunately I didn't take chemistry in high...
  16. resurgance2001

    Carbon dioxide and global warming

    Hi I have a simple question about global warming. The percentage of carbon dioxide in the Earth atmosphere is about 0.04% . My question is how is such a small percentage of this gas able to have such a powerful affect on global warming? Thanks
  17. M

    MHB Find the amount of moles of carbon dioxide produced during the reaction

    i.If all the calcium carbonate used in set up X was used up for the reaction, what is the amount of moles of carbon dioxide produced during the reaction ? (Ca = 40, C = 12, O = 16) My progress: Molar mass of CaCO3=(40+12+(16*3))gmol-1=100 gmol-1 Molar mass of CO2=12 + 16* 2 gmol-1=44 gmol-1...
  18. R

    Carbon dioxide in water, analysis of dissolved species HPLC?

    Does anyone here have any analytical experience with dissolved gas, particularly CO2? When CO2 is dissolved in water there can be several reactions: What I would ideally like to do is dissolve CO2 into water and then by some means of analysis, see how much of each species there is in the...
  19. wolram

    Turning carbon dioxide into fuel

    I am no chemist but i found this article interesting, is it viable and suited to mass production https://www.sciencedaily.com/releases/2016/08/160825113217.htm Date: August 25, 2016 Source: University of Toronto Summary: Every year, humans advance climate change and global warming by injecting...
  20. H

    How do volcanoes produce carbon dioxide?

    I am just curious where this gas comes from when volcanoes erupt.
  21. Docscientist

    CO2: A Vital Component of Our Environment?

    Homework Statement What is the importance of CO2 in our environment? Homework Equations None The Attempt at a Solution CO2 can help is keeping the Earth warm.It can be used by the plants to release oxygen during day.It can be used by decomposers.
  22. Raptor112

    Carbon Dioxide in the Martian Ice Caps

    Homework Statement The Viking landers on Mars measured a seasonal change in surface pressure of 2.5 mb due to the variation in the seasonal extent of the ice caps. Ignoring any elevation variations on the surface of Mars, calculate the difference in the total mass of CO2 in both ice caps...
  23. B

    Sound waves in carbon dioxide -- I think book answer is *wrong*

    Homework Statement Sound waves can be refracted when they travel through balloons filled with different gases. How would the motion of a sound wave be changed if it traveled through a balloon filled with carbon dioxide?BOOK ANSWER "Being more dense than air, the carbon dioxide in the balloon...
  24. J

    Electrical DIY Atmospheric Carbon Dioxide Detector?

    I thought it would be an interesting project to build a detector that will measure and log the outdoor atmospheric CO2 levels. These (global average) levels are currently about 400ppm and these (global average) levels vary by a few ppm every year. Looking for a sensor though, I can't seem to...
  25. electric jake

    Electrical Resistance or Conductance of Carbon Dioxide

    I wanted to do a science experiment and it is very important that i learn the electrical resistance of carbon dioxide. From what i would guess, this may be wrong, but carbon dioxide and the atmosphere on Earth probably have a similar electric resistance due to the fact carbon dioxide already...
  26. W

    CCS Carbon Dioxide Storage Capture

    Hi, What is in general the most cost-effective way of the CCS technologies: Post,pre or oxyfuel combustion?
  27. Kior

    Why has CO2 decreased in the history of the Earth?

    I noticed that the Co2 is actually decreasing in the Eon time. My guess is lush vegetations or forests began to grow which absorbed the Co2 by photosynthesis? Would anyone give me any clue?
  28. Kior

    What is the difference between a carbon sink and reservoir?

    I am trying to figure out the difference between a carbon sink and a carbon reservoir. The definition for a carbon sink from wikipedia is that “carbon sinkis a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period. ” And the...
  29. Kior

    What is the difference between carbon sink and reservoir?

    I am trying to figure out the difference between a carbon sink and a carbon reservoir. The definition for a carbon sink from wikipedia is that “carbon sink is a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period. ” And...
  30. Kior

    Timescale of the biological pump?

    I'm tying to find any clue about the timescale of the biological pump. That the carbon is recycled to the surface ca. 1,000 years is clear but the timescale of the biological pump seems hard to find. There is an report I saw when I was surfing the internet saying that the timescale can range...
  31. Kior

    Why is there a seasonal cycle of CO2?

    I am preparing my AOSS class next semester, and I found it is interesting that there is a seasonal cycle of CO2. I looked for some information on the Internet, and this seems to do with the plants. They awake in the spring and summer, absorbing a lot of CO2 by photosynthesis and die in the...
  32. U

    How much will the atmospheric carbon dioxide change?

    Homework Statement Suppose ##10^{14} kg## of carbon dioxide was released into the atmosphere and absorbed completely, what is the percentage change of carbon dioxide concentration? Take initial atmospheric mass mixing ratio to be ## 5.7 \times 10^{-4} kg/kg##. Homework EquationsThe Attempt at...
  33. Sirluke

    Vapor pressure curve for carbon dioxide

    Hello to everyone. I would like to ask a question: I'm analyzing the properties of CO2 for a project and I have noticed that for temperatures between 220 -300 K the Clasius Clapeyron curve is linear on 1/T, that is in the Antoine equation of the form logP = A-B/(T+C), C is almost 0. In my...
  34. N

    Calculating CO2 Rotational Constant | J=0,1,2,3,4,5 Excited State Analysis

    Hey! I have a problem. The problem is simple: calculate CO2 rotational constant. I have values for J (ground state and excited state), with those grades I have to calculate rotational constant. I know that for J=0,2,4.. it is just in ground state and for J=1,3,5..it is excited state. But how do...
  35. A

    How to Calculate Energy for Atmospheric Molecule Reaction and Isolate Gases?

    The atmosphere consists of two toxic, and unfortunately abundant gases in our atmosphere. Carbon dioxide and methane. Carbon dioxide produced by factories are not needed in the atmosphere and cause harm. So is methane. Acegikmoqsuwy and I thought of an equation to solve this problem: CH4 + CO2...
  36. MexChemE

    Enthelpy change for a real gas (Carbon dioxide)

    Homework Statement Find ΔH for the isothermal expansion of one mole of CO2 from a pressure of 1 atm to zero at 300 K. The critical point of CO2 is TC = 31 °C and PC = 73 atm. Use the equation for ΔH you previously derived from the Berthelot equation of state. (Answer provided by textbook: ΔH =...
  37. E

    Will (NH4)HCO3 Form in Polar Solvents?

    I know aqueous Ammonium Bicarbonate forms when NH4+ and HCO3- ions are present in water after they've dissolved from their gaseous states of NH3(g) and CO2(g). This occurs in the reaction: NH3(g) + H2O(l) + CO2(g) => (NH4)HCO3(aq) If Ammonia gas and CO2 are present above a polar organic...
  38. N

    Is carbon dioxide equally distrubuted throughout the Earth?

    Is carbon dioxide at relatively the same concentrations in China, America and Antarctica for example? Or (I'm not discussing altitudes) does the concentration of carbon dioxide fluctuate based on where you are on the Earth? Assuming that all measurements are made at the same altitude, would the...
  39. Infinite/Zero

    Carbon dioxide & oxygen balance

    Green Plants do Photosynthesis in day during presence of sunlight and intake C02 to produce O2. In night, Plants do respiration and intake 02 to produce C02. If there will be no animal then Green plants will survive ? Because Earth is like ball, Plants will do photosynthesis=respiration...
  40. N

    Dissolving carbon dioxide from air without dissolving any other gases.

    Hello, Me and two other people are doing a science research competition for high school students and for our project we thought of a machine that takes in air through a pump and dissolves CO2 and only CO2. The problem is I don't know what to put in for a solution or pure liquid that would...
  41. S

    Carbon Dioxide Output Percentage Change

    Homework Statement Question: If petroleum used in transportation were replaced by electricity generated by coal, what would be the percentage change in carbon dioxide output? Refer to the following diagrams for values...
  42. M

    Total Carbon Dioxide emissions for 2013

    Hello there I've been searching the internet for any information about the total carbon emissions for this year (tonnes/year). However, I've only come across data which is most recently been gather a few years ago (2009 - 2011). However, I'm really curious to what the total emissions are...
  43. A

    Why isnt carbon dioxide a solvent?

    So, CO2 is said to be non polar because of its molecular geometry. However the carbon atom has two positive charges and the oxygens, one partial charge each. Therefore, why doesn't CO2 dissolve ionic molecules like NaCl? We've been taught that a polar molecule is one that can separate ionic...
  44. L

    Alevel paper 3 chemistry: titration vs collection of carbon dioxide over water

    Homework Statement titration method is more accurate than collection of carbon dioxide over water method to solve stoichiometry equation. Homework Equations what are the 3 reasons? The Attempt at a Solution some carbon dioxide has leak into the air, carbon dioxide is partially...
  45. M

    State of carbon dioxide during fermentation

    Homework Statement I know that the process of fermentation occurs in two steps, however, in the second step where glucose/sucrose is broken down into ethanol and carbon dioxide, is the carbon dioxide expelled as a gas or in an aqueous state? (I'm assuming water is involved here)Homework...
  46. K

    Airborne Spray that changes colour where Carbon Dioxide is present

    We are looking to produce a spray changes colour when it comes into contact with Carbon Dioxide. Ideally this would be colourless when sprayed, but become a visible "smoke" where carbon dioxide is present. Failing this, we are open to a white "smoke" that changes to coloured where Co2 is...
  47. Y

    Is it dangerous to compress carbon dioxide under high pressure?

    Is it dangerous to compress carbon dioxide under high pressure?
  48. A

    Why is Carbon Dioxide in Tonic Water? Exploring Taste and Texture

    If carbon dioxide is the gas we exhale and is not healthy to breathe back in, then howcome they put carbon dioxide gas in tonic water?!
  49. S

    Carbon dioxide density & distribution in the atmosphere

    carbon dioxide is heavier than air, so how there is a layer of CO2 is forming around the atmosphere?
  50. M

    Carbon dioxide removal from biogas

    I've been searching the posts here and I think this question may be a little below most of you. I've cobbled together a homemade biogas generator and I'm wanting to improve the quality of the biogas by removing some of the CO2 (or all of it if I can) which will leave me with a higher calorific...