# Tag Info

11

I'm guessing your teacher is looking for sulfur dioxide as the answer, but I don't see how or why you're supposed to be able to arrive to this answer logically. Either you'd need to read about it specifically, or maybe you're supposed to stare at a table of standard reduction potentials and notice that $\ce{SO2}$ appears as both a reagent and as a product ...

9

Unfortunately, there is no caliper-like tool to measure ionic radii directly. They are determined based on experimental data such as crystal structure or crystal lattice energy using empirical relationships. The exact value would inevitably deviate from one method to another. Pauling [1, pp. 150–152] used a hard-sphere model which doesn't account for ...

6

The key to the answer is understanding how FID works. The hydrogen flame has a minimal flame ionisation, what is needed for the low signal baseline. Incoming organic molecules from the HPGC column create in the flame a lot of ions and increase the flame electric conductivity. Using alternatives causing higher ionisation would decrease FID sensitivity that ...

6

You can define the size of atoms and molecules in various ways. You can, for instance, derive a measure of the size of a hydrogen molecule from the density of solid hydrogen: Solid hydrogen has a density of 0.086 g/cm3 making it one of the lowest-density solids. From the above you can derive an effective radius for $\ce{H2}$ of $\pu{2.10 Å}$, which is ...

6

The easiest way to grow diamond through chemical vapor deposition (CVD) is on a heated filament, which just takes a few watts. You'd need a low-pressure chamber (~30 torr, or ~0.04 atm) with gas-tight fittings for electricity, feed-gas of ~1% $\ce{CH4}$ and ~99% $\ce{H2}$ and $\ce{Cu}$, $\ce{Ti}$, $\ce{W}$ or $\ce{Ta}$ filaments. Since this is a flow-...

4

In electrochemistry, the rate of electrolysis depends on rate of charge entering the cell. Second most important point is that one can either control potential or current but not both during electrolysis i.e. you cannot have both values set. If you are fixing potential at 2.5 V, the value of current is not in your hand. I don't think Ohm's law remains valid ...

3

Both of these reactions are thermal decomposition reactions, but the difference basically occurs in the polarizing power of the cations $\ce{Ca^2+}$ and $\ce{Mg^2+}$ . The thermal decomposition of $\ce{Ca(HCO3)2}$ is just the reverse reaction of the lime water test for the detection of $\ce{CO2}$ , where the carbonate combines with $\ce{CO2}$ and $\ce{H2O}$ ...

3

The equilibrium constant for the reaction $\ce{2H2 + O2 <=> 2H2O}$ is colossal, equal to $\mathrm{2.4 \times 10^{47}}$ at $\mathrm{500\ K}$ (source). This would ensure virtually 100% yield for the combustion of a stoichiometric mixture of oxygen and hydrogen in equilibrium conditions. However, a rocket engine is a reaction vessel that is far from ...

3

To begin with, removing another proton from anionic species is not very favorable. For example, the monohydrogen phosphate dianion is not very acidic $(\mathrm{p}K_\mathrm{a}\sim 12)$ despite it having an $\ce{OH}$ group. In the case of $\ce{H3PO2},$ the second and third protons are bonded directly to $\ce{P},$ which is much less electronegative than $\ce{O}... 2 Many nuclear power plants use so-called "passive autocatalytic recombiners" for the catalytic oxidization of hydrogen that could be released into the containment in the event of severe accidents. (Note that the affected units of the Fukushima-Daiichi plant did not have such equipment.) The catalytically active materials, typically platinum and/or palladium, ... 2 You guessed it right that hydrogen and oxygen mixtures will remain stable. Someone in Harvard waited for >30 years and found very little water if any. As you said, there is a energy barrier. What type of materials can lower this barrier? Catalysts. The electrode materials require some catalysts such as platinum or nickel. Of course, making cheaper and ... 2 Another fundamental aspect of using hydrogen in gas chromatography is the so-called van Deemter curve. The curve shows the linear velocity of the gas on the x-axis and plate heights on the y-axis. It can be shown that by using hydrogen one can obtain the best efficiency as compared to any other gas. And of course, hydrogen is required for burning the ... 2 It would be nice to have a full chromatogram rather than a cropped one to see how other peaks look like. The phenomenon of odd behavior of hydrogen with helium as carrier gas with TCD detector in quite well known, but I am not sure if it has been investigated in detail in the literature or not. Hydrogen has higher thermal conductivity than helium. Ideally ... 2 The thermodynamics are always the same. If you go from carbon monoxide to methane, there is only one final enthalpy, and if you have the choice of going to methane or methanol the thermodynamically preferred product is always the same. The difference indeed less within the different pathways and the activation barriers needed to get from one intermediate to ... 2 Catalysts generally decrease the electrode overpotential, which leads to decreasing the needed voltage to perform electrolysis at given current densities toward its minimal theoretical value. If higher current is possible at the same voltage due the catalyst, the lower voltage is needed for the same current, both leading to better efficiency. As the energy ... 2 The bubbles are still hydrogen. Transition metal salts are generally much weaker acids than whatever you put your magnesium ribbon into for your hydrogen control. So you get less gas for the candle flame to react with when you use the transition metal salt, which I am sure you saw. That the decreased amount of gas still popped, which is basically a low-... 2 The scheme starts with the production of OH radicals since Hydrogen dissociation is very endothermic (432 kJ/mole) compared to$\ce{H2 + O_2 \to 2OH\cdot}$which is the initiation reaction with$\Delta H^{\mathrm{o}}_{298} = 72$kJ/mole. There is a propagation reaction and two chain branching reactions and gas phase termination as well as wall termination ... 1 From a structure diagram alone it is hard to determine these interactions. The reason for this is that important structural parameters are stretched or shortened in order to flatten the molecule for a 2D drawing. In a first order approximation a molecular modelling kit based on balls and sticks could already be very helpful. It'll let you approximate the 3D ... 1 One of the ways of achieving what you have thought about, is a fuel cell, as Karl mentioned in his comment. However, since you have asked about efficiency, I will try to address that question in particular. What can be done is to produce the hydrogen at some factory, and then use the hydrogen as a fuel (like petrol) that can be loaded into the car to be ... 1 Electrostatic repulsion between electrons is the key to understanding$\ce{H-}$. The electrons might be delocalized, but they are also correlated - they avoid each other. Both electrons of the hydrogen ion have the same energy level and they don't shield the charge of the core from one another. The Aufbau and Pauli exclusion principles (and the ... 1 A few binary metal hydride candidates: Magnesium hydride gives about 0.11 grams of hydrogen per cubic centimeter, and unlike water it can release its hydrogen leaving the element behibd on simple heating. It does, however, require 287°C to decompose, limiting reversibility. Lithium hydride offers nearly the same hydrogen density as the magnesium compound ... 1 In gaseous/plasmatic phase, there is no difference -$\mathrm{p}$and$\ce{H+}$are synonyms for a proton. The former ( p, proton ) is more often used by physicists in subatomic particle context, the latter by chemists in hydrogen properties/behaviour context. In polar solvents like water or liquid ammonia, "naked" protons nor electrons cannot exist, but ... 1 There are many software packages that do what you request. PHENIX, Schrodinger, SCWRL4. It depends on how accurate you want, and options for pH etc. 1 There has been a lot of promising buzz around hydrogen. Many people believe that hydrogen can be used as an energy carrier to replace other fuels like gasoline in the near future. One of the largest challenges to use hydrogen in a wide scale is its storage after hydrogen is produced. Some storage technologies have currently been developed. Yet, according to ... 1 Hydrogen is the only element with thermal conductivity greater than helium ($0.182$vs$\pu{0.151 W\,m^{-1}K^{-1}}$at$\pu{25 ^{\circ}C}$) as M. Farooq pointed out (cf., thermal conductivity of$\ce{N2}$is$\pu{0.026 W\,m^{-1}K^{-1}}$at$\pu{25 ^{\circ}C}$). The mixtures of$\ce{H2}$in$\ce{He}\$ at moderate temperatures exhibit varying thermal ...

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