Only a few metals-the Group I metals and calcium, strontium, and barium from Group II- react with water at room temperature.
#Mcat practice test torrent series#
The reactivity series also predicts the reactivity of a metal with water. The zinc reacts to displace the nickel ions as follows:
A metal that is above another is more reactive and will take the place of the lower, less reactive metal in a compound.įor instance, a student places a sample of zinc metal into a solution of nickel (II) nitrate. The reactivity series for metals is a summary of the results of many single displacement experiments. In single displacement reactions, one element takes the place of another in a compound. Which converging lens scenario will NOT produce an image?Īn important class of oxidation-reduction reactions is called single displacement. The following table lists four different scenarios of a converging lens, with each scenario detailing the distance of an identical object placed in front of the same converging lens as well as the focal length of the lens.
A converging lens positioned in front of a hyperopic eye acts to focus the light rays sooner so that they converge on the retina rather than behind the retina.Ĭorrection of hyperopia is accomplished with a converging lens tailored to characteristics unique to the person. Hyperopia, as is the case with many vision problems, can generally be corrected with eyeglass lenses, specifically a converging lens, as shown in the figure.
This results in the ability to see distant objects clearly with vision becoming blurry for close objects. Hyperopia, or farsightedness, is a common vision problem that occurs as a result of these light rays entering the eyeball but converging behind the cornea. Image formation in the human eyeball occurs when parallel light rays refract through the eye lens and converge on the retina. When 1 mole of sodium metal reacts with 1 mole of chlorine gas to form solid sodium chloride, what is the heat of formation? Some lattice energies are given in the table. If the charge is constant, increasing size lowers the lattice energy. If the size is constant, increasing charge increases the lattice energy. Lattice energies depend on the charge and on the size of the ions in the array. The higher the lattice energy, the stronger the attractions and the higher melting the solid. The lattice energy of an ionic compound is a measure of the attractive forces between the ions. In solid sodium chloride, each positive ion is surrounded by 6 negative ions, and each negative ion is surrounded by 6 positive ions in a cubic lattice array. Most of the energy that is given off is due to the formation of solid sodium chloride from the gaseous ions. The chloride ion reacts with the sodium ion.Ĭl – (g ) + Na + (g ) → NaCl (s) ΔH o rxn = −771 kJĪddition of the five elementary equations gives the sum equation for the formation of solid sodium chloride. This quantity is the electron affinity of chlorine.ĥ. This quantity is the first ionization energy of sodium vapor.Ĭl (g ) + e – → Cl – (g ) ΔH o rxn = −349 kJ Na (g ) → Na + (g ) + e – ΔH o rxn = 496 kJ \frac Cl2 (g ) → Cl (g ) ΔH o rxn = 121 kJ The reaction takes place in five elementary steps: The energy that is released is the enthalpy of formation of solid sodium chloride, which is also called the heat of formation. The reaction between sodium metal and chlorine gas is spontaneous and releases energy. The most reasonable major hydration product of 3,6-dimethylcyclohex-1-ene using water and sulfuric acid is: One workaround for this problem is the oxymercuration-demercuration sequence, as shown here:Ĭonsider the hydration of 3,6-dimethylcyclohex-1-ene under two separate conditions, for which four different alcohol products are proposed: The limitation of this method is that a carbocation is generated along the mechanistic pathway, opening the door to rearrangements, as shown in the sulfuric acid–catalyzed hydration of 3,3-dimethylbut-1-ene here: Many alkenes can be hydrated simply by treatment with a strong acid in the presence of water. MCAT Chemistry Practice Test 2023 Test NameĬhemical and Physical Foundations of Biological Systems
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