Helen asks…
hydrogen???????????????
Helium and hydrogen???
in the early 1900s hydrogen gas was used to inflate airships after on large ship crashed and caught on fire teh helium gas began to be used to inflate air ships .why was helium preffered over oxygen?
admin answers:
Oxygen isn’t “lighter than air”.
Ken asks…
Hydrogen??????????????
(H2O+NaOH+Al) is the formula of chemicals we used. Where might the hydrogen gas come from?
admin answers:
Hydrogen is one of the substances making up the water. Of water composer .. Sorry, .. I’m usually the
Mary asks…
How green would a hydrogen car industry be in a world wide scale?
I have been reading a number of articles about changing to hydrogen cars and how it would result in a decrease in pollution. While it is true a hydrogen car would be a number of times cleaner than a regular gas car, I have a few doubts about how clean the hydrogen making process would be. If hydrogen obtained from water, wouldn’t it require a great deal of energy to get the hydrogen out of it? Wouldn’t the energy required to do this come from oil and the more traditional non-green energy sources? Overall, is the process for obtaining enormous amounts of hydrogen overall green at all?
admin answers:
The fossil fuel powered split would only be necessary at the very beginning of the process. Hydrogen releases more energy than is required to split H from O2, so you’d be producing Hydrogen by means of a Hydrogen powered process. Green all the way around.
Switching to hydrogen power would do way more than just decrease pollution. It would also make energy very cheap because the process of splitting water is relatively simple. You could literally have a mini power plant behind your house producing a great, clean source of energy, that powers your entire house, and your car. Fuel stations could produce hydrogen on location.
In large cities, for safety purposes, there would probably still be a reliance on energy companies, to prevent having large quantities of such an explosive within city limits. Imagine if a city were to start to burn with pockets of hydrogen everywhere? I’m reminded of the great chicago fire and the san francisco fire.
But yes, you can totally have a green process for splitting hydrogen from oxygen.
Carol asks…
How does the reaction of hydrogen and oxygen to produce energy in a fuel cell differ from direct combustion?
A. It is much easier to control the hydrogen and oxygen during direct combustion than during their reaction in a fuel cell.
B. Much less heat energy is produced in a fuel cell than via direct combustion of hydrogen and oxygen.
C. In the fuel cell, there is an oxidation-reduction reaction between hydrogen and oxygen. In the direct combustion of hydrogen and oxygen, there is no such reaction.
D. The direct combustion of hydrogen and oxygen produces several different products, whereas the fuel cell produces only water.
admin answers:
2H2 + O2 –> 2H2O …. The same reaction occurs in both combustion and a fuel cell.
None of your answers are particularly satisfying, even the one that the question writer thinks is correct, which is (B).
While it is true that much less heat is produced in the fuel cell, the question implies that there is less energy change in the fuel cell. That simply isn’t true. The change in energy is the same regardless of whether the reaction occurs in an instant, as in the explosive combustion of H2 and O2, or over a much longer time, as with the exchange of protons and the corresponding movement of electrons, in a fuel cell. The only difference is the time interval over which the chemical change occurs, the rate of reaction.
Joseph asks…
How much hydrogen is in a liter of Gasoline, and in a liter of liquid Hydrogen?
I have heard somewhere that there is actually more hydrogen in a given volume of Gasoline than in the same volume of liquid hydrogen. I’ve been trying to check on that, but haven’t found what I’m looking for yet.
admin answers:
Density of liquid hydrogen is 67.8 kg/m3
density of gasoline is about 750 kg/m3
let’s assume gasoline is octane, C8H18, even there are actually many chemical compounds in gasoline. Octane has a mole weight of 114 kg/kmol, with 96/114 coming from carbon and 18/114 coming from hydrogen. Therefore the octane is 16% hydrogen.
16% of 750 kg/m3 is 118 kg/m3 hydrogen in octane
118 kg/m3 > 67.8 kg/m3
Indeed, there is more hydrogen is a given volume of gasoline than in a given volume of liquid hydrogen.
Betty asks…
What happens to hydrogen in the presence of platinum?
I know that hydrogen is adsorbed onto the surface of platinum, but is it still molecular hydrogen (H2), or does it break up into hydrogen atoms (H•), for example?
I know that hydrogen adds across a carbon-carbon double bond, how can it do this if it’s still molecular hydrogen?
Are there any other reactions that hydrogen can take part in, in the presence of platinum, other than adding across a carbon-carbon double bond? If hydrogen does break up into hydrogen radicals, is it free to react with anything else which may be present in solution?
admin answers:
Great Q.
H2 adsorbs on the surface of Pt, then dissociates into H atoms which bond to surface Pt atoms but can skate around from one site to another.
The alkene is also chemically adsorbed onto the Pt surface, using its pi-electrons.
We then have the reactions
Surface H + C2H4 –> surface C2H5
Surface C2H5 + surface H –> Gaseous C2H6
The reaction is not so much of free radical reaction, as the addition of “Pt-H” across the double bond (compare the addition of H-Br)
In solution, H2 bubbled over finely divided Pt gives the famous “platinum electrode”, which catalyses redox equilibria involving H2 and H+:
H2 2 surface H
surface H + H2O H3O+ + e- on Pt
This electron can be transferred to reducible species in solution, or supplied to a second electrode in an electrochemical cell.
Michael asks…
How much hydrogen can be extracted from a given quantity of water?
On my job I’ve used a hydrogen generator to extract hydrogen gas from water. The process uses a large bank of lead-acid batteries and highly purified water. We compress it and store it for use with weather balloons.
Assuming you used a 100% efficient process, much more efficient than the primitive process we use, how many cubic feet of hydrogen can be extracted from 1 liter of water?
admin answers:
1 liter of H2O = 55.6 moles of H2O (1000 g/18 g/mol)
H2O –> H2 + 1/2 O2
Expect 55.6 moles H2 at 100% efficiency
55.6 moles at STP = 55.6×22.4 liters = 1244 liters
1244 liters = 43.9 cubic meters (m^3)
Powered by Yahoo! Answers