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MechRocket
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The answer to my Kaplan test (studying for the DAT, just FYI) says 3, but I think it's 4?
Am I wrong?
Am I wrong?
SpectraCat said:To which structural isomer of octane are you referring? And do you mean non-equivalent hydrogens?
Assuming you mean n-octane, I think you are correct in principle that there are 4 kinds .. in other words, if you use the substitution test, you can create 4 distinct molecules by substituting a single H-atom with an F-atom. However, for the purpose of determining NMR shifts in alkanes (which I assume is what you are asking about), I am fairly sure that only the nearest-neighbor groups matter. Assuming that is true, can you now see why n-octane has only 3 non-equivalent types of hydrogens?
sjb-2812 said:I'd be inclined to disagree there, even for NMR, though for e.g. distinguishing between 3- and 4-halooctanes there may not be that much of a difference in shift, in principle this still exists.
The number of equivalent hydrogens in a molecule can be determined by looking at its structure and counting the number of identical hydrogen atoms that are bonded to the same type of carbon atom. In octane, all eight hydrogen atoms are bonded to primary carbon atoms, making them equivalent.
Knowing the number of equivalent hydrogens in a molecule is important for predicting its chemical and physical properties. In octane, the equivalent hydrogens play a role in determining its boiling point, flammability, and reactivity with other molecules.
No, only the eight hydrogens bonded to primary carbon atoms are considered equivalent. The two hydrogens bonded to the tertiary carbon atom in octane are not equivalent due to their different chemical environments.
The number of equivalent hydrogens in octane does not affect its formula, which is C8H18. However, it does affect its molecular weight, as each equivalent hydrogen adds 1 atomic mass unit (amu) to the overall molecular weight. Therefore, octane has a molecular weight of 114 amu (8 carbons x 12 amu + 18 hydrogens x 1 amu).
No, the number of equivalent hydrogens in octane cannot be determined solely by its chemical formula. It requires knowledge of its molecular structure and the different types of carbon atoms present. A structural formula or 3D model of the molecule is necessary for accurate determination of equivalent hydrogens.