What is the reaction between sodium carbonate and nitric acid?
It’s a typical acid-base reaction:2HNO3 +Na2CO3 → CO2 + H2O + 2NaNO3End product is Sodium Nitrate in solution, plus plenty of carbon dioxide gas bubbles and water. The sodium and hydrogen cations essentially trade places, but the carbonic acid produced (H2CO3) dissociates into carbon dioxide & water due to the exothermic nature of the reaction, with the CO2 coming out of solution.
What is the oxidation number of Cr in K2Cr2O7?
First you have to ‘break up’ the potassium dichromate into its elements.K = potassiumO = oxygenCr = chromium.Dismissing the uncharged neutral elements as possibilities (oxidation state = 0), figure out the most common (or in the case of potassium the only) ionic form(s) or oxidation numbers of each element in the formula.K[math]^{+}[/math] = Potassium ion (positive one charge)O[math]^{2-}[/math] = Oxide ion (negative two charge)—always true except for peroxides (-1) or OF[math]_2[/math] (oxygen difluoride, +2)K[math]_2[/math]Cr[math]_2[/math]O[math]_7[/math] is a neutral salt overall; net charge = 0Only chromium is a ‘wildcard’ here as it can exhibit multiple oxidation states: II, III, or VI (there are others but I, IV, or V are seldom seen outside inorganic research). Same as Cr[math]^{2+}[/math], Cr[math]^{3+}[/math], or Cr[math]^{6+}[/math].Multiply the charges according to the formula, the sum being set as zero. “Cr” is being used as the algebraic unknown variable in the math below.0 = 2 x (K[math]^+[/math]) + 7 x (O[math]^{2-}[/math]) + 2 x Cr(?)0 = 2(+1) - 7(-2) + (2 x Cr) = 2 - 14 + 2Cr = -12 + 2CrRearrange the order of the equation.2Cr - 12 = 0Add 12 to both sides.2Cr = 12Finally, divide both sides by 2.Cr = 6That means the chromium ions have formal charges of +6 or an oxidation state of VI in potassium dichromate.
I dont Understand my blood test results?
With the number 3 it could have meant 3 mcg (micrograms)/dl(deciliter) of blood. That's anywhere from 10 to 20 times less than what would be the healthy minimum level. Ask him for a copy of your lab results and what you should do for your iron deficiency Adding more iron in the diet through red meat, supplements, and vegetables may not be enough for you. I'd recommend acting quickly too. Having 10 to 20 times less the minimum healthy level sounds serious .
Calculate the maximum wavelength of light that will ionize magnesium.?
Convert 735.0 kJ mol-1 to J per photon: (735.0 *1000)/(6.022 x 10*23) = 1.2205*10-18 J λ = h*c/E = (6.626x10^-34* 2.998 x 10^8)/(1.2205*10-18) = 1.6276*10^-7 m λ = 162.8 nm far UV (<180 nm) as you would expect http://en.wikipedia.org/wiki/Electromagn...
How do I calculate the group of the element by electronic configuration?
Write the electronic configuration. The highest Principal quantum number in the configuration gives the period, and the Electron shell(subshell) coming last is the group of the element. The number of electrons filled in the last subshell gives the position of the element within the group. For example,The configuration of iron is4 is the highest principal quantum number.Hence, it belongs to the 4th period.Last subshell is the d- subshell. Hence it belongs to d-group.6 electrons are filled in last subshell.Hence it the 6th element in the d-group of the 4th period.
Can shells of atoms temporarily have more than their maximum number of electrons?
When electrons absorb photons of a particular energy they can move to outer shells of that atom. However they can release this energy in two separate steps by emission of two photons of different energies. Does this mean that temporarily a shell of an atom may have more than their maximum number of electrons? For example: A photon is absorbed by an electron which moves from n=0 to n=3. This leaves a deficit of electrons in the n=0 shell. This electron then moves from n=3 to n=2, emitting a photon. Then it moves from n=2 to n=0 emitting another photon. But isn't the n=2 shell already full? How can the electron moving down from the n=3 shell be accommodated? Can somebody please explain to me how this works? Many Thanks
How to calculate the binding energy ???
The He atom is composed of 2 protons, 2 neutrons and 2 electrons. The mass of 2 protons = 2 x 1.007277 amu The mass of 2 neutrons = 2 x 1.008665 amu The mass of 2 electrons = 2 x 0.0005486 amu The sum of the masses is 4.032981 amu The actual mass, as measured by a mass spectrometer, is 4.002603 amu. The difference (4.032981 - 4.002603) is 0.030378 amu For one mole of He atoms the difference would be 0.030378 grams Why is there a difference? If we were to break apart a He atom into protons, neutrons and electrons, a tremendous amout of evergy would be required. The amount of energy is called the binding energy. Obviously if we were to form a He atom from protons, neutrons, and electrons a tremendous amount of energy would be released. The amount of energy is equal to the binding energy. Where did the energy come from? Einstein showed that mass and energy are related by the equation E = mc^2.. Using the speed of light, c, of 2.9979x10^8 m/s and the mass that was lost when the He was formed (3.0378x10^-5 kg) the calculated binding energy is 2.7302x10^12 kg m^2 s^2. 1 joule = 1 kg m^2 s^2 so the binging energy of 1 mol He = 2.73x10^12 J/mol or 2.73x10^9 kJ/mol. The binding energy is usually expressed in energy units of Mev (1 million electron volts). 931 MeV is approximately equal to the mass of 1 amu. Thus, the mass of 0.030378 amu = 931 x 0.030378 = 28.3 MeV The binding energy of a He atom is 28.3 MeV The He atom is composed of 4 nucleons (2 protons + 2 neutrons), so the average binding energy per nucleon is 28.3 MeV/4 = 7.07 MeV. The average bindfing energy per nucleon varies for different atoms.