Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  ..  92    94  
Author: Subject: The Short Questions Thread (4)
paulll
Hazard to Self
**




Posts: 73
Registered: 1-5-2018
Member Is Offline

Mood: It's fine. Really.

[*] posted on 27-4-2021 at 11:22


Quote: Originally posted by njl  
Nope, all my samples are odorless.


Good to know, ty.
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 2343
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 27-4-2021 at 17:48


My NaBr is slightly halogeny...perhaps from the original crystallization or reaction with the container at some point. Our noses are very sensitive analytical instruments sometimes...e.g. a super low concentration of IPA smells pleasant and is unrecognizable as such.



"You're going to be all right, kid...Everything's under control." Yossarian, to Snowden
View user's profile Visit user's homepage View All Posts By User
j_sum1
Administrator
********




Posts: 5538
Registered: 4-10-2014
Location: Oz
Member Is Offline

Mood: Taking opportunities to breathe.

[*] posted on 4-5-2021 at 15:56
Hypotherical hydrogen cyanide synthesis


I just composed a problem for my students – calculation of enthalpy of reaction from tables of average bond energies.

Seemed like an ok example of the concept. But is there a feasible reaction schema that produces HCN from ammonia and carbon monoxide?

Just curious.

Bond Energy question.jpg - 2.1MB
View user's profile View All Posts By User
DraconicAcid
International Hazard
*****




Posts: 3802
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline

Mood: Semi-victorious.

[*] posted on 4-5-2021 at 16:14


I don't think so, but that's a good example.



Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
View user's profile View All Posts By User
njl
International Hazard
*****




Posts: 584
Registered: 26-11-2019
Location: under the sycamore tree
Member Is Offline

Mood: ambivalent

[*] posted on 4-5-2021 at 16:30


Carbon monoxide is a better reducing agent than it is an oxidizing agent, and ammonia needs to be oxidized to give cyanide.



Reflux condenser?? I barely know her!
View user's profile View All Posts By User
j_sum1
Administrator
********




Posts: 5538
Registered: 4-10-2014
Location: Oz
Member Is Offline

Mood: Taking opportunities to breathe.

[*] posted on 4-5-2021 at 17:03


Quote: Originally posted by njl  
Carbon monoxide is a better reducing agent than it is an oxidizing agent, and ammonia needs to be oxidized to give cyanide.

Should have thought of that.
(Shhh. I won't tell the students. It will ruin the illustration.)
View user's profile View All Posts By User
paulll
Hazard to Self
**




Posts: 73
Registered: 1-5-2018
Member Is Offline

Mood: It's fine. Really.

[*] posted on 4-5-2021 at 17:13


Quote: Originally posted by j_sum1  

(Shhh. I won't tell the students. It will ruin the illustration.)


Too late to offer bonus marks for balancing the equation?
View user's profile View All Posts By User
j_sum1
Administrator
********




Posts: 5538
Registered: 4-10-2014
Location: Oz
Member Is Offline

Mood: Taking opportunities to breathe.

[*] posted on 4-5-2021 at 17:34


Quote: Originally posted by paulll  
)[/rquote]

Too late to offer bonus marks for balancing the equation?

It is an exercise to introduce a concept and not an assessment. So, no marks. What is required is clarity, and a situation that is non-trivial to give purpose to the exercise and so that the required concepts are repeated a few times. This meets those criteria.
View user's profile View All Posts By User
scienceboi
Harmless
*




Posts: 30
Registered: 12-9-2019
Location: California
Member Is Offline

Mood: Curious

[*] posted on 26-5-2021 at 15:04
Question


Can metals become plasmas? And how easy or useful is it to make them plasma?

I was just looking up sputter deposition for silicon wafers and it got me thinking.




"Read not to contradict and confute; nor to believe and take for granted; nor to find talk and discourse; but to weigh and consider." -Francis Bacon
View user's profile View All Posts By User
Hoffit
Harmless
*




Posts: 21
Registered: 12-8-2019
Member Is Offline

Mood: Excited

[*] posted on 27-5-2021 at 00:09


Applied science has some nice videos about sputtering like this one https://www.youtube.com/watch?v=9OEz_e9C4KM
View user's profile View All Posts By User
pneumatician
National Hazard
****




Posts: 338
Registered: 27-5-2013
Location: Catalonia
Member Is Offline

Mood: ■■■■■■■■■■ INRI ■■■■■■■■■■ ** Igne Natura Renovatur Integra **

[*] posted on 29-5-2021 at 22:43


What is the ideal acid nitric concentration for dissolving Iron? 30%? 20%? 10%?...

Pure of around 99,9x% and "normal" Iron filing?

[Edited on 30-5-2021 by pneumatician]
View user's profile View All Posts By User
Fulmen
International Hazard
*****




Posts: 1516
Registered: 24-9-2005
Member Is Offline

Mood: Bored

[*] posted on 30-5-2021 at 00:34


I would say it depends on what you're after. If it's reaction speed it would probably be strong acid, but that tends to produce lots of NO and NO2. For a clean reaction with little loss I would keep the concentration below 20%.



We're not banging rocks together here. We know how to put a man back together.
View user's profile View All Posts By User
B(a)P
International Hazard
*****




Posts: 645
Registered: 29-9-2019
Member Is Offline

Mood: Confined

[*] posted on 30-5-2021 at 00:39


Concentrated nitric acid will passivate iron.
View user's profile View All Posts By User
clearly_not_atara
International Hazard
*****




Posts: 2176
Registered: 3-11-2013
Member Is Offline

Mood: Big

[*] posted on 30-5-2021 at 05:54


Quote: Originally posted by j_sum1  
I just composed a problem for my students – calculation of enthalpy of reaction from tables of average bond energies.

Seemed like an ok example of the concept. But is there a feasible reaction schema that produces HCN from ammonia and carbon monoxide?

If you factor entropy into your calculations I'm betting you'll find that delta-G is always positive for the forward reaction (forbidden). But IIRC you can do it in two steps, by making formamide first and using a selective catalyst second.




[Edited on 04-20-1969 by clearly_not_atara]
View user's profile View All Posts By User
pneumatician
National Hazard
****




Posts: 338
Registered: 27-5-2013
Location: Catalonia
Member Is Offline

Mood: ■■■■■■■■■■ INRI ■■■■■■■■■■ ** Igne Natura Renovatur Integra **

[*] posted on 31-5-2021 at 20:50


what is the Pepy's apparatus???
View user's profile View All Posts By User
Belowzero
Hazard to Others
***




Posts: 159
Registered: 6-5-2020
Location:                 Member Is Offline
Member Is Offline


[*] posted on 6-6-2021 at 12:21


Will acrylate or plexiglass resist ~30% nitric acid for long periods of time at room temperature?
Or PVC?
View user's profile View All Posts By User
CharlieA
International Hazard
*****




Posts: 587
Registered: 11-8-2015
Location: Missouri, USA
Member Is Offline

Mood: No Mood

[*] posted on 6-6-2021 at 14:51


Quote: Originally posted by pneumatician  
what is the Pepy's apparatus???


https://en.wikipedia.org/wiki/William_Haseldine_Pepys

May be this will help? You didn't mention in what activity the apparatus might be used in.
View user's profile View All Posts By User
njl
International Hazard
*****




Posts: 584
Registered: 26-11-2019
Location: under the sycamore tree
Member Is Offline

Mood: ambivalent

[*] posted on 6-6-2021 at 16:12


Carboxylic acids can be activated by formation of mixed anhydrides. Could the acid instead be reacted with isocyanate to yield a carbamate (mixed carbamate anhydride)?



Reflux condenser?? I barely know her!
View user's profile View All Posts By User
pneumatician
National Hazard
****




Posts: 338
Registered: 27-5-2013
Location: Catalonia
Member Is Offline

Mood: ■■■■■■■■■■ INRI ■■■■■■■■■■ ** Igne Natura Renovatur Integra **

[*] posted on 9-6-2021 at 00:17


someine use one of this? ocerall qlty?? leaks in joint???

https://www.ebay.de/itm/152510588408?ssPageName=STRK%3AMEBID...
View user's profile View All Posts By User
pneumatician
National Hazard
****




Posts: 338
Registered: 27-5-2013
Location: Catalonia
Member Is Offline

Mood: ■■■■■■■■■■ INRI ■■■■■■■■■■ ** Igne Natura Renovatur Integra **

[*] posted on 9-6-2021 at 00:25


Quote: Originally posted by CharlieA  
Quote: Originally posted by pneumatician  
what is the Pepy's apparatus???


https://en.wikipedia.org/wiki/William_Haseldine_Pepys

May be this will help? You didn't mention in what activity the apparatus might be used in.


near 0 info in archive and gbooks! :-?
View user's profile View All Posts By User
SHADYCHASE54
Hazard to Others
***




Posts: 148
Registered: 16-12-2010
Location: CaNaDay!
Member Is Offline

Mood: No Mood

[*] posted on 10-6-2021 at 06:01


Hello fellow S.M'ers,
I am wondering if I were to make hypophosphorus acid with it's Na salt and 32% HCl; then flash distill the resulting solution under strong vacuum to remove H2O, precipitate most of the NaCl while keeping the acid's boiling point below its d-comp. What would be, after diluting the acid to 10-15 percent of course, the most suitable exchange resin(s') to remove the Na and Cl impurities? Would reacting the diluted solution first with H+ strong acid cation exchange resin convert the remaining NaCl to HCl? Furthermore I am wondering if I were then to react the resulting solution with a strong anion exchange resin in the Cl- form would this remove the Cl from the HCl impurity thus liberating the hydrogen (g)?

I have no idea if this would work past making the acid solution. Anyone with experience or knowledge with or about exchange resins, who is willing to point me in the right direction, I would really appreciate it.

2 side notes: 1 yes I am aware of the danger of this acid's decomp. products. 2 the hypo is not for any illicit use, truthfully I haven't even decided what I intend to reduce yet? As the real experiment is in reaction conditions and comparing those to similar reducing agents. I am also interested in comparing it's reducing capacity under various reaction conditions. Such as simple reflux, microwave irradiation and under pressure. (In an actual pressure bomb). There I'm done.

Any help would be appreciated.
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 3125
Registered: 8-2-2015
Location: UK ... on extended Holiday in Malaysia
Member Is Offline


[*] posted on 22-6-2021 at 20:38
TCCA + EtOH = Chloroform?


I have performed the classic acetone + hypochlorite haloform reaction a couple of times,
I would like to try TCCA instead of hypochlorite,
will it make much difference if I use EtOH (85% or more) instead of acetone.
(I have lots of (pool grade, 90%)TCCA and diy EtOH)




CAUTION : Hobby Chemist, not Professional or even Amateur
View user's profile View All Posts By User
BauArf56
Hazard to Self
**




Posts: 67
Registered: 22-8-2019
Location: between the moon and the sun
Member Is Offline

Mood: energetic

[*] posted on 29-6-2021 at 11:33
is it possible to isolate any chlorinated compound by burning propane in chlorine?


Once i wanted to see how does propane (or butane) burn in chlorine gas, so i lighted up the blowtorch inside a bottle filled with chlorine. It burned with a bigger flame and it was quite luminous too. After a few seconds of burning inside the bottle there was no smell of chlorine at all, just the typical sweet smell of chlorinated compounds. Can anyone explain which compounds form and if is it possible to isolate them as liquids? Thanks
View user's profile View All Posts By User
macckone
International Hazard
*****




Posts: 1990
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline

Mood: Electrical

[*] posted on 29-6-2021 at 11:46


Quote: Originally posted by pneumatician  
someine use one of this? ocerall qlty?? leaks in joint???

https://www.ebay.de/itm/152510588408?ssPageName=STRK%3AMEBID...


I have not bought that particular one, but they are commonly used in labs. For large quantities they have significant advantages in filling and cleaning. The top portion generally uses a standard 100mm opening, you can buy various sealing rings but the ground glass joints should meet as well as a standard vacuum desiccator.

You can buy various tops for the flask:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p23220...
View user's profile View All Posts By User
macckone
International Hazard
*****




Posts: 1990
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline

Mood: Electrical

[*] posted on 29-6-2021 at 12:04


Quote: Originally posted by Sulaiman  
I have performed the classic acetone + hypochlorite haloform reaction a couple of times,
I would like to try TCCA instead of hypochlorite,
will it make much difference if I use EtOH (85% or more) instead of acetone.
(I have lots of (pool grade, 90%)TCCA and diy EtOH)


TCCA will not work by itself. You will have to add a soluble hydroxide base. And you will need extra as the cyanuric acid will need to be neutralized to form the final product.
There is actually a thread on TCCA.
http://www.sciencemadness.org/talk/viewthread.php?tid=5686

Ethanol will work, It has an alpha carbon.
Ethanol was used in the first haloform reaction.
Since you normally add water in the form of bleach or to dissolve the calcium hypochlorite, the water content won't matter much.

However, ethanol and chloroform give an azetrope so you need to be sure your ethanol totally reacts. Acetone has a similar issue with separation.
View user's profile View All Posts By User
 Pages:  1  ..  92    94  

  Go To Top