Difluoromethanealso called HFC or Ris an organic compound of the dihalogenoalkane variety. It has the formula of CH 2 F 2. Difluoromethane is a molecule used as refrigerant that has zero ozone depletion potential ODP a global warming potential GWP index times that of carbon dioxide, based on a year time frame and it is classified as A2L - slightly flammable by ASHRAE. Difluoromethane has excellent heat transfer and pressure drop performance both in condensation and vaporisation.
Therefore, in spite of its mild flammability, it seems to be a very promising low GWP substitute for traditional HFC refrigerants. The zeotropic mix of difluoromethane with pentafluoroethane R and tetrafluoroethane Ra is known as RA through RE depending on the composition. Likewise the azeotropic Difluoromethane is currently used in residential and commercial air-conditioners in Japan, China, and India as a substitute for RA.
In order to reduce the residual risk associated with its mild flammability, this molecule should be applied in heat transfer equipment with low refrigerant charge such as brazed plate heat exchangers BPHEor shell and tube heat exchangers and tube and plate heat exchangers with tube of small diameter .
Many applications confirmed that difluoromethane exhibits heat transfer coefficients higher than those of RA under the same operating conditions but also higher frictional pressure drops .
From Wikipedia, the free encyclopedia. This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Difluoromethane . Carbon fluoride hydride Methylene difluoride Methylene fluoride Freon CAS Number. Interactive image.
Beilstein Reference. Gmelin Reference. PubChem CID. Chemical formula. Autoignition temperature. Structure and properties. Spectral data. The PubChem Project. International Journal of Refrigeration.
Other names Carbon fluoride hydride Methylene difluoride Methylene fluoride Freon EC Number. R-phrases outdated. S-phrases outdated. S9S16S Phase behaviour solid—liquid—gas.Transcript: Hi, this is Dr. Let's do the Lewis structure for CH2F2: difluoromethane. On the periodic table, Carbon is in group 4, it has 4 valence electrons. Hydrogen, group 1, but we have 2 Hydrogens. Fluorine, 7 valence electrons, we have 2 of those as well, for a total of 20 valence electrons.
We'll put the Carbon at the center, and then Hydrogens always go on the outside. And the Fluorines are very electronegative so they go on the outside, as well.
We'll start by putting two valence electrons between each of the atoms to form a chemical bond, and that's used up 2, 4, 6, 8. We have Let's go around the outside: 10, 12, 14, 16, 18, So we've used all the valence electrons.
Let's see if we have octets. Hydrogen only needs two valence electrons, so it's OK. Fluorine needs 8, this Fluorine has 8 and this Fluorine has 8. And then Carbon, in the center, needs 8, and it has 8. Everything has full outer shells. The difference is that you have H and F in this Lewis structure.
Remember that Hydrogen only needs 2 valence electrons for a full outer shell. For the CH 2 F 2 Lewis structure there are a total of 20 valence electrons available. See the Big List of Lewis Structures. Opens New Window. That is the Lewis structure for CH2F2. This is Dr.Polarity in a molecule is determined by the summation of the polarity of the bonds. Basically, look at each bond in the molecule, and the greater the difference in the electronegativities of the atoms in the bond, the more polar that bond is.
In three-dimensional space, some of the bonds may cancel each other out. For example, take CF4. All four of the C-F bonds are polar, but in the molecule as a whole, they are all cancel each other out due to how they are oriented spacially.
CH2F2, though, polar. This is because there are two different kinds of bonds, which are two C-H bonds and two C-F bonds. There is a net polarity to the molecule because of this. An easy way to look at it is if all the atoms connected to the central atom are the same, as in CF4, then the molecule will not be polar.
Also, you can check the molecule for symmetry. Hope that helps. Oh, and a polar molecule will tend to have a higher boiling point. This is due to the fact that there is more energy that needs to be invested into the polar bonds to get the molecule to heat up enough to boil. Basically, the more polar the molecule is, the more energy is needed to get it to boil.CH2F2 Lewis Structure - How to Draw the Lewis Structure for CH2F2
If you need any clarification, feel free to message me and I'll give you some examples with pictures. Good luck! Polarity is caused by uneven electron density in a molecule. This is due to atoms which tend to draw electrons away from other atoms. CF4 is nonpolar because all the atoms surrounding the carbon are identical. This is not the case with CH2F2. The two fluorine atoms draw electrons away from the hydrogen atoms, making this molecule polar.
Because of the polarity, there is a weak attraction between areas of high and low electron density between molecules. This draws the molecules together and elevates the boiling point. Therefore, CH2F2 would have a higher boiling point. Answer Save. Paula Lv 4. This Site Might Help You. Ch2f2 Polar Or Nonpolar. Still have questions? Get your answers by asking now.Chiral molecules usually contain at least one carbon atom with four nonidentical substituents.
Such a carbon atom is called a chiral center or sometimes a stereogenic centerusing organic-speak. Any molecule that contains a chiral center will be chiral with the exception of a meso compound. You need to be able to quickly spot chiral centers in molecules.
All straight-chain alkyl group carbons CH 3 or CH 2 units will not be chiral centers because these groups have two or more identical groups the hydrogens attached to the carbons. When looking at a molecule, look for carbons that are substituted with four different groups. See, for example, if you can spot the two chiral centers in the molecule shown here.
Because CH 3 and CH 2 groups cannot be chiral centers, this molecule has only three carbons that could be chiral centers. The two leftmost possibilities, identified in the next figure, have four nonidentical groups and are chiral centers, but the one on the far right has two identical methyl CH 3 groups and so is not a chiral center. He received his PhD at the University of Maryland in He is currently a chemistry professor at Iowa State University. How to Identify Chiral Centers in a Molecule.
Which is nonpolar: CF4 or CH2F2?
A chiral center. A molecule with two chiral centers. The chiral centers in a long molecule.Three cases can be constructed that do not follow the Octet Ruleand as such, they are known as the exceptions to the Octet Rule. Following the Octet Rule for Lewis Dot Structures leads to the most accurate depictions of stable molecular and atomic structures and because of this we always want to use the octet rule when drawing Lewis Dot Structures.
However, it is hard to imagine that one rule could be followed by all molecules. There is always an exception, and in this case, three exceptions. The Octet Rule is violated in these three scenarios:. Reminder: Always use the Octet Rule when drawing Lewis Dot Structures, these exceptions will only occur when necessary.
The first exception to the Octet Rule is when there are an odd number of valence electrons. Nitrogen atom has 5 valence electrons while the oxygen atom has 6 electrons. The total would be 11 valence electrons to be used. The Octet Rule for this molecule is fulfilled in the above example, however that is with 10 valence electrons.
The last one does not know where to go. The lone electron is called an unpaired electron. But where should the unpaired electron go? The unpaired electron is usually placed in the Lewis Dot Structure so that each element in the structure will have the lowest formal charge possible.
The formal charge is the perceived charge on an individual atom in a molecule when atoms do not contribute equal numbers of electrons to the bonds they participate in. The formula to find a formal charge is:.
No formal charge at all is the most ideal situation. An example of a stable molecule with an odd number of valence electrons would be nitrogen monoxide. Nitrogen monoxide has 11 valence electrons Figure 1. If you need more information about formal charges, see Lewis Structures.
Nitrogen normally has five valence electrons. In Figure 1, it has two lone pair electrons and it participates in two bonds a double bond with oxygen. Oxygen normally has six valence electrons. In Figure 1, oxygen has four lone pair electrons and it participates in two bonds with nitrogen.
Oxygen therefore has a formal charge of 0.Gillespie 1 Estimated H-index: 1. Find in Lib. Add to Collection. References 0 Citations 27 Cite. Stephen Berry. Read Later. An Electron Diffraction Study. BartellKathryn W. Stereochemistry of Phosphorus V Fluorides.
MuettertiesAfter signing in, all features are FREE. References 0. Cited By Sigma-holes from iso-molecular electrostatic potential surfaces. Molecular Structure by Quantum Chemistry. Putz H-Index: Revue des structures de ces composes, complexes ou autres.
Les flexibilites stereochimiques, pentacoordination dans les mecanismes de reaction, principes et deformations de structure sont etudies. Reminiscences about electron waves. Bartell H-Index: 1.C F F Copy Copied. For medical information relating to Covid, please consult the World Health Organisation or local healthcare provision.
Simple Structure Advanced History. Comment on this record. Khladon 32 [Russian]. CF2 [Formula]. R 32 [DBID]. Freon 32 [DBID]. Petersburg Univ. NIST Spectra nist ri. Ref: Hansch,C et al. Click to predict properties on the Chemicalize site. Search ChemSpider: Compounds with the same molecular formula Compounds with the same skeleton Use this molecule in a structure search. Extremely Flammable SynQuest Flammable SynQuest R18,R67 SynQuest Personal Collections.
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