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About agaubr

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    Male, married, retired after 27 years in industry and currently teaching Chemistry in college
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  1. Get the carbonate by weight loss due to heating and you have NaHCO3 ---> Na2CO3 + H2O + CO2 and if heat higher temperature >200C Na2CO3 ---> NaO + CO2 The the resulting salt left can be titrated with AgNO3 to yield AgCl (s) which can then be collected and dried to get the chloride which must be equal to the sodium from the NaCl. agaubr
  2. Usually the simple way to describe ionic compounds is to say they are composed of a metal and nonmetal element such as NaCl, CaCO3, etc. A covalent compound is composed of nonmetals such as CH4, O2, N2, etc. When you add an ionic compound to water such as NaCl, table salt, you might describe this action as NaCl (s) ---> Na+(aq) + Cl-(aq) indicating the salt is a solid and with the addition of the water becomes dissolved. However the dissolution cause the solid crystal matrix to being held together by electrostatic interaction of a positively charged sodium ion and a negatively charged chloride ion to come apart so that the ions are now dissolve din water. the ions are now surrounded by polar water molecules which can interact with the charged ions by a dipole-ion interaction which causes the ions to stay in solution. Therefore when an ionic salt dissolves it is no longer a slat but discrete ions in solution which have different properties and behave differently. So when you say I dissolved an ionic compound you have a very important statement and description of the system. As for covalent compounds such sugar they dissolve as a unit and do not form charged systems and their properties are different. However, there are exceptions such as molecular HCl(g) in the gas phase becomes an H+(aq) and Cl-(aq) when in water. It is this property which allows for the acidity of the solution due to the formation of H+(aq). agaubr
  3. It ow appears the best model suggest all things are made up of the fundamental moiety called a string and follows "M Theory or The Theory of Everything". In response to your questions: 1) The octet rule suggests the most number of electrons to occupy an outside valence shell is 8 which works pretty good for the group A elements although their are exceptions. Many exceptions are found in the group B series. The reason for the 8 is you are filling the s and p orbitals for the group A so you can only have 8 electrons. 2) Boron does not pick up the five electrons due to energy considerations and driving the system to a higher energy state and thus create an instability. But using the three electrons it has Boron does do some very unique things and creates some very interesting compounds and bonding patterns such as spreading two electrons over three atoms to yield a 2/3 bond. 3) The use of more complex atoms versus carbon to create life seems to a tough one to answer except to say it is easier to do it this way in our current system of physical reality. My simple answer is energy again. the driving force to do something is to produce a system which has lower energy than reactants so you get a downhill energy plunge. To go uphill will require some complex happenings and then there must be a reason for this to be stabilized so can exist. Good questions. Sometimes these questions are buried in philosophy more so than science. agaubr. agaubr.
  4. Polar molecules do not need to have lone pairs of electrons but most do. The concept is that one atom has a stronger pull toward the electrons in the valence shell than the other atom to the point that the molecule develops slight charges of + and - on the molecule. This development of partial charge causes the molecuel to behave as charged moiety.
  5. a) The fact of the ethylene witha sigma bond and a pi bond for the double bond causes the atoms to be closer togther due the pi bond mst overlap the p-orbitals for bonding b) H-N-H bond is from thefact ammonia is sp3 hybrid which is teterahedral where the bond should be 104 deg 28 minutes, but hte wider angle is due the lone pair of electrons on the ammonia and causes the tetrahedreal to distort c) SO3 bondlinks are shortew due the fromation of resonance stabilized structures with electron sharing on all three bonds being the same
  6. Yes this reaction would occur, forgot about insoluability of the copper hydroxide being much greater than magnesium hydroxide.
  7. The issue is Cu solid due the nature of the activity series only slats of silver, mercury, platiumum or gold would interact with the copper to casue the copper to form Cu2+ and free other metal. the sulphates of most of these metals is insoluable in water and so will take a while for reaction to occur. But you the sulphate salt ofthe other metals.
  8. My guess is yes the blue is CuSO4, but the white milky tacky material is Mg(OH)2 which insoluable in the water. The reaction is an electrolysis whereby the Cu is oxideized to Cu2+ and the water is converted to H2(g) and OH-. Te ydroxide ion concentratio increase until overwhels the vinegar and then reacts with Mg2+ t form the Mg(OH)2. You try o filter the solution but my guess is it will be very slow and clog the filter. But with patience and lng noug wit and water washing the CuSO4 will be isolated.
  9. The normal method is related to the chemistry of silver which when exposed to the ligth darkens and then reverst back in the dark.
  10. Read michael Crighton's book "Prey"
  11. The picture you describe is an electron density map which predicts where the most likelhood you will see an electron with that particular energy. A spherical descrption is for a s-orbital whcih can occur with pricinpal quntum numbers of 1, 2, 3, 4, 5, 6, 7, 8, etc. The pricipal quantum number describe the distance from the nucleus the electron is located with thelarger values being greater distance from the nucleus. There are othe rorbitals with much more variation in shape as the p, d, f, and g's.
  12. Ka X Kb = Kw so if you know one or the other can caluate the since Kw = 1 X 10-14.
  13. PKb is the log [ 1/Kb] where is the equilibrium constant for a base which tells the extend of inioization of the base and the increase in the [OH-] or decrease in the [H+]. A week base would have a pH greater than 7 but less than 9. A pH of 13 is a very strong base since [H+] is very low and mostly [OH-] present in solution. Ag
  14. agaubr


    How do you explain the photoelectric efect if the photon has no mass? Ag
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