This paper is a follow-up to my post from last week: C02 is a polar molecule.
It was initially published on the Machinima blog and the Machinima archive.
The center focuses on the physics behind C02’s behavior and why it looks like this (from a chemical perspective)
2. What is CO2?
CO2 has been around for quite some time, but it has recently become a hot topic in the tech world. Only a few years ago, it became clear that CO2 is essential to life on Earth. And now, the amount of CO2 our atmosphere is made up of is increasing at an alarming rate due to anthropogenic activities.
The lack of awareness around this fact makes us all nervous. We have a good reason: CO2 is an essential greenhouse gas that traps heat in the atmosphere and warms it up, allowing more water vapor and other greenhouse gases to escape into space. This warming effect is one of the reasons why global temperatures are rising much faster than they used to be over the past century or so, which we call the “hockey stick” graph.
Co2 exists in nearly pure form (about 6% by weight), which means that approximately half of all CO2 that we breathe in and exhale comes from sources other than human activity, such as natural gas or agricultural emissions (pesticides are also necessary). The other half comes from burning fossil fuels — coal especially — which releases CO2 when it burns, as well as deforestation and other land use.
To get carbon dioxide out of the atmosphere, we need to help plants deal with it by capturing it before it ever reaches the ground (when our plants take up CO2, they do so through photosynthesis). This process doesn’t happen quickly enough for us humans to feel its effects directly. Still, it suffices to say that over time there will be an increase in atmospheric concentrations of carbon dioxide, which will impact climate science and society on a wide scale.
3. The structure of CO2
CO2 is a polar molecule. It has no single permanent covalent bond (i.e., unlike H2O, which has two permanent bonds). This means that CO2 can be either a gas or a liquid depending on the temperature and pressure at which it is found (this property is why it is used to cool buildings and refrigerators).
The molecule’s leading functional group is CO (which can be oxidized to CO2 and O2 with the same efficiency). Still, it also contains several more oxygen atoms, which means there are four different possible structures:
The most common one – an H-bonded oxygen atom that joins two carbon rings – has been dubbed “CO-O.” The other three structures are all carbon rings with one oxygen atom bonded to the central carbon ring (called “CO-C”), one oxygen atom bonded to the main crew (called “CO-S”), or one oxygen atom attached to two adjacent rings (called “CO-CCS”).
The bond lengths between oxygen atoms vary from around 10 Å in CO-S to about 14 Å in CO-CCS. This variation means that many molecules have different chemical properties depending on whether they contain an equal number of O atoms or an unequal number of O atoms. The CoO structure doesn’t mainly differ from these other structures when viewed under polarized light because it contains only one O atom per ring, which doesn’t change under polarized light. But when viewed under ultraviolet light, the two rows of O atoms are visible as two distinct bands.
Henri Moissan first observed this type of structure in 1904; however, he did not realize its significance until he used it as a model for another molecule – chlorine dioxide – in 1916. He noted that this new chemical could be oxidized through UV rays into chlorine dioxide and then purified through oxidation into chlorine trioxide.
4. The polarity of CO2
The carbon dioxide (CO2) molecule is the simplest molecule in the periodic table of elements and was initially believed to be a non-polar molecule. However, experiments conducted in 1815 showed that CO2 is a polar molecule – subsequent experiments confirmed this during the 19th century.
In 1819 William Thomson proposed that a non-polar molecule would have a negative charge if it had an electron. Early experimenters attempted to confirm this hypothesis by measuring the lead on various compounds with and without non-polarity, but they failed to detect any difference. They found no difference between compounds with and without non-polarity. This discrepancy was simple: electrons were inherently attached to atoms or molecules rather than dispersed throughout space for some compounds.
However, following Thomson’s work, it was realized that all chemical bonds are formed from polar molecules and that these molecules do not always possess an electron pair (which would render them non-polar). In 1913 the atomic theory of matter was postulated by Ernest Rutherford and subsequently confirmed by experiment. It is now known that CO2 is ubiquitous; however, some scientists still believe that it has been incorrectly classified as a “non-polar gas” based on past experiments which were too crude to detect anything other than its specific physical properties.
5. The dipole moment of CO2
One of the essential properties of CO2 is its dipole moment. And one of the most important ways to measure it is by measuring the polarization of light emitted when two wavelengths of light are passed through a gas at different angles.
The dipole moment is defined as,
P i = − ( L i − λ 1 ) ( L i − λ 2 ), where P i is the polarizability, L I and L 2 are the lengths of the two wavelengths, and λ one and λ 2 are respectively the frequencies of emitted light at high and low pressure. If we have an electric field E, the field at point A in Fig. (1) will cause a force F o on an electron whose charge is equal to E o. This force acts perpendicularly to the direction of E o so that it acts on both electrons O in A.
If we have a magnetic field B, its focus will be perpendicular to E o, so this field works on both electrons O in A. These forces will cancel out, so no details exist between O in A and B. Therefore, the total force acting on O in A is F = 0.
Fig. 1: Electric field + magnetic field produces forces on two electrons (O) in each atom’s nucleus that is canceled out by other forces. In particular: F = 0 .
This interaction between E and B can be used to determine the polarizability of a molecule by finding how much force F o causes an electron to change its orientation from being oriented perpendicularly towards B or towards O in A — this is described with polarizable molecules as vectors having components pointing either way with magnitude equal to F o φ for positive values (−F/F p for negative values).
Since this projection has parts telling, either way, any vector v can be written as v = A + e B where e is some small constant known as w w w w w w w r or simply for short because it is independent of any length scale r r r r r r r r d d d d, which should mean that v = −A + B = (−A) + B
6. The intermolecular forces in CO2
The Intermolecular forces in CO2 – Carbon Dioxide
This is a simple question, but the three types of CO2 molecules are different. The first is CO2 (or HCO3), which has a molecular formula of C20H24O2. The second is CO2 (or H2CO), which has a molecular formula of C20H22O3. The third, 3-hydroxymethyl, has a molecular formula of C18H21OH.
We have to give this answer because many people think each type of molecule can dissolve in water. This isn’t true. For example, here is a diagram illustrating the intermolecular forces between water molecules at different temperatures:
This shows that some forces are keeping the water molecules apart that is stronger than the hydrogen bonds. When the temperature increases, these forces become weaker, and it’s easier for those water molecules to touch one another to form hydrogen bonds with each other again. So when you try to dissolve one type of molecule in water at a higher temperature than it was disbanded at its average temperature, you will generally get mixed results:
At room temperature (about 20°C), these two types of molecules interact very strongly with one another and form hydrogen bonds with each other:
However, on increasing the temperature above 20°C, two kinds of molecules start to break apart and lose their bond strength, so they can no longer interact with one another:
The CO2 (carbon dioxide) debate is a topic that has been going on for decades. In the early days, people worried that CO2 emissions would be a significant problem, and some even feared that the world would run out of carbon. However, as time went on, the situation got better and better. When you look at it objectively, the artificial contribution to atmospheric CO2 is a minuscule fraction of what’s released in nature (one percent of total carbon dioxide emissions comes from artificial sources).
The fact that there are places on this planet where atmospheric CO2 levels are higher than others means there must be some other way to get rid of it.
There is another possibility: you’re an astronaut floating in space and can see all those green plants growing around you. Is it possible that they are absorbing CO2 and converting it into something else?
The answer is yes, and we believe it’s fascinating! The carbon dioxide we cast into the air does not just vanish. It gets reabsorbed by life in our atmosphere — plants, for instance — and by itself again, many times over! We have not previously been able to prove this scientifically — but we think it’s very likely! And if we can confirm this experimentally, why not use it as inspiration to find new ways to make the air even cleaner?
If you want to learn better about how living things transform carbon dioxide into other forms of energy, check out this video: