The Periodic Table

Q: What is the difference between hydrogenation in presence of platinum and nickel catalyst?

11:07 AM

@paracetamol Okay, thanks.

paracetamol

;-)

Bounty Hunter

I got option $\ce{C}$ as an answer, but the answer is $\ce{D}$ as well. I have never seen the difference in reduction by change of catalyst. I have absolutely no idea about $\ce{D}$. Is there any difference?

organic-chemistry hydrocarbons organic-reduction

3 hours later…

user 2646

1:42 PM

people.idsia.ch/~juergen/sci.html

^fun site to browse, start at the main article

:-)

2 hours later…

Martin - マーチン

3:24 PM

@Zhe Would you terribly miss 20 reputation? Your one line answercomment blocks automatic deletion O.o See: Why does this reaction changes from colourless to blue

Zhe

@Martin-マーチン I don't mind

easy come, easy go

For future reference, you do not need to clear these with me

I trust your judgment

Martin - マーチン

3:40 PM

@Zhe Thanks, but we generally don't do anything (esp. deleting) without a second opinion. In this case it seemed easier talking directly to you than spam another one in spring cleaning :D

Zhe

@Martin-マーチン It's not setting me any farther back for my silver organic badge, so we're good to go :D

2 hours later…

5:20 PM

> Ammonia gas NH3 is found in STP conditions and occupies volume V completely dissolved in distilled water. The concentration of the solution is 20 % by weight and the density is 0.9 g/ml. The final volume of the resulting solution is 500 ml.

Hm, I guess they actually mean

> Ammonia gas NH3 is found in STP conditions and occupies volume V. Completely dissolved in distilled water, the concentration of the solution is 20 % by weight and the density is 0.9 g/ml. The final volume of the resulting solution is 500 ml.

Otherwise it would just be V = 500 ml.

@Abcd There really is no point adding the word attempt to the question body. If it is an attempt at solving the problem, that should be fairly obvious... — Martin - マーチン ♦ 6 hours ago

@Martin-マーチン I think highlighting attempt is OK. It doesn't do any harm.

2 hours later…

7:33 PM

@Abcd This decarboxylation q. maybe wouldn't fit into homework, but is unclear. Like every such acid undergoes decarboxylation in one situation or another.

But that's not the issue. The issue is:
Is mentioning "Attempt" in the question (any question) OK or not?

@Abcd Well, you made it look more like homework and it's not a particularly good thing.

Well, it highlighted it doesn't necessarily violate HW policy, and it's probably gonna be opened

Still I'd rather put something like "easily" decarboxylate because of the group or something to make it more clear.

Questions get often the HW reason while other ones may fit better

gateprep

7:56 PM

@Mithoron I need one genine hep

@Mithoron Why is the harndness of Aluminium and Copper different in terms of indentation?

Somebody replied me

The electron configuration of Al (Ne 2s2 p1), where in the most outer electron shell (the 3rd.) there there are 2 on the s-level and only 1 on the p-level. But copper has not only the 3p level filled (6electrons), but also the 4s shell (2 electrons) and has further 10 electrons on the 3d level. It is more than double as heavy than Al.

However Electrons don't have much much mass that will contribute.Please explicitly get into the greated detail of it.

@gateprep You know that electrons are much lighter then protons, but don't remember that their numbers are equal?

Cu 2+ is much softer then Al 3+ because it's much bigger and has lower charge

Q: Determine the thermal efficiency of a steam turbine from given input and output steam conditions, steam flow rate and power output

8:32 PM

I like such questions:

An oil-fired boiler takes in feed water at 75 °C and produces wet steam at a pressure of 5 bar. The steam flow rate 1.50 t/h with a dryness fraction of 0.89. The fuel consumption rate is 6.10 kg/min and its net calorific value is 41 MJ/kg. Determine the thermal efficiency of the boiler.

physical-chemistry thermodynamics

Too bad that the asker didn't try anthing to solve it.

@Loong Hmm? Maybe because of tenuous connection with nuclear reactors?

Yes, there you find such things, too.

Although "wet steam at a pressure of 5 bar" would be bad. ;-)

We would have 75.5 bar here.

@Loong Meh, unless you get to ionic water at dunno how many kbar, it's kinda boring ;D

@Mithoron Neverthless, we would make 2443 kg/s of that boring stuff. ;-)

Always something ;)

8:48 PM

@Loong Also the title is misleading. The question is about the boiler and not about any turbine.

nature.com/articles/ncomms1566.pdf?origin=ppub

14 Mbar and we get to something :D

Martin - マーチン

@Abcd I think it's starting the obvious. If it's there I won't edit it out, but I wouldn't edit it in either. A question should stand on its own without any meta commentary. I think these things are in the end distracting.

Edit statements, however, are even worse. They usually artificially separate a question into parts. That's not helpful in the long run. If anyone is interested in the edit history, there's already a link for it. But that is of course a different story...

@Loong nucular ;p