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Стиральный порошок [May. 27th, 2017|01:45 am]
Chemistry Help

nicka_startcev
после стирки в машине с "обычным порошком" одежда жутко воняет ароматизатором из этого порошка.

тройное полоскание с двойной дозой воды не очень помогает.

и да, я живу в петербурге, вода мягкая, смягчители не особо нужны.

собственно вопрос-1. можно ли из репертуара ленреактив/невареактив/магазинхимик/хозмага и прочих доступных не-юрику не-прекурсоров (а также ебая/али) собрать некую замену стиральному порошку, которая будет вообще без ароматизаторов?

вопрос-2. что нужно добавить к "лаурилсульфат натрия" или аналогичным солям сульфокислот чтоб получился "обычный стиральный порошок", пригодный для указанных условий?
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Oppolzer's Camphorsultam and Arndt-Eistert [Oct. 27th, 2012|04:13 pm]
Chemistry Help

tom_mouse

Hello everyone!

My supervisor has given me a reaction from before I started my PhD to talk through during a presentation and I'm considering questions that may be asked in the Q&A. I'm struggling to work out how Oppolzer's camphor sultam works. I found one explanation that said "steric hindrance of the dimethyl group in conjunction with repulsion of the amide nitrogen lone pair". I just wanted to make sure that's right, as I've only found descriptions of selectivity when a sulfone oxygen coordinates to a Lithium enolate, whereas I have a silyl enol ether in my actual reaction.


Also, does anyone know why sonication and a catalyst would be needed for an Arndt-Eistert reaction? I thought the reaction happened pretty easily?

Thanks so much in advance :)

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Exam Preparation [May. 31st, 2012|12:03 pm]
Chemistry Help

alexidior
Hi,

I have a Chemistry exam in 2 weeks and was hoping to get some help with questions I'm going through from previous years exams that were were given without answers and I'm stuck on.



I'm stuck on this one because despite having attended every class, I don't remember us ever having touched on calculating molar conductivity but am worried that they put E in there to trick us. The answer I'd go for if I saw this in my exam would prolly be A because it's the difference between CsNO3 and HF.



This I'm stuck on again because of option E. My understanding is that vapor pressure decreases after the addition of a solute so the highest would be pure water leaving me with C and D. I don't know where to go from here.

Thanks a million in advance.
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Gallium oxides [Jan. 6th, 2012|02:15 am]
Chemistry Help

the_oldman
Dear сolleagues,
I had an unsolved problem. I have a gallium oxide, which is a mixture of three modifications: α-, β- and ε-Ga2O3.

The question: is how to get rid of the β-Ga2O3 in this mixture?

P.S. Option, described in Wikipedia (heating β-Ga2O3 at 65 kbar and 1100 C) is not considered, the pressure does not build.
Is there some other way?
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Chemical Equilibrium [Sep. 7th, 2011|12:36 pm]
Chemistry Help
jinx24
Hey it's me again! I have a question about chemical equilibrium.

At temperatures near 400 C, the Kp value for the synthesis of ammonia is 2.5 x 10-4. At 400 C, what would be the approximate value of K for the following reaction?

3H2(g) + N2 (g)⇔ 2NH3 (g)

So, the equation for the partial pressure is Kp = Kc(RT)Δn

Δn-2-4= -2

To solve for Kc, it's Kc= Kp/RTΔn

so it's Kc= 2.5 x 10-4 / (0.821 L atm/Kmol x 673.15 K)-2

Only I get a different answer than what's in the book.

Can anyone tell me where I went wrong? Thanks!
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Reaction Rates [Aug. 19th, 2011|04:08 pm]
Chemistry Help
jinx24
Hey, I was wondering if anyone could help me with a problem regarding reaction rates



For the following reaction in a 4.00-L container, it was found that 1.00 x 10-4 mol of C4H8 reacted over a time period from 10:58 A.M. to 11:15 A.M.

C4H8 (g) --> 2C2H4 (g)

What is the average rate, in M/s, for this reaction?

I took the time period of 10:58-11:15, which is 17 minutes, and did dimensional analysis to figure out what it was in seconds (1020 s). I set the equation up as

1.00 x 10-4 M
--------------
1020 s

and got 9.8 x 10-8 but the answer is 2.5 x 10-8. I don't know what I'm doing wrong.



Thank you to anyone that can help!
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10% solution [Jun. 29th, 2011|09:29 pm]
Chemistry Help

sarah1234567891
HI

I need to make  10% formic acid   (my formic acid has a 88% purity)


i'm confused as to how to do this. let's use 100 mL to make it easier to calculate.


Do I:

A.  10 mL formic acid + 90 mL H20

or

B. 10 mL formic + 100 mL H2O?


When do I use A and when do I use B to calculate?



I was making a 0.1% Formic acid in water 1 L solution, I used calculation B to make the solution.  1.14 mL of formic acid + 1000mL H2O.
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(no subject) [Apr. 24th, 2011|05:09 pm]
Chemistry Help

tom_mouse
Does anyone know how to remove the acetate from this molecule, leaving a terminal olefin? It's not homework, I'm doing a past exam paper as revision and the final molecule has no OAc, but the first part of the question was about selective acetylation? 
Thanks so much! :)
Photobucket
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Estimating Delta G at a given temperature? [Mar. 7th, 2011|04:43 pm]
Chemistry Help

grayinfinitum
In class a few days we are given this problem. I understand the first part because, but I have no idea how to estimate Delta G at 400 K. The answer is provided, but can anyone help inform me on how that answer was obtained?

Use a table of thermodynamic properties to determine So and Go at 298K for the following reaction:
4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g)
So = 1180.45 J/mol-K

 

Go =2-959.14 kJ/mol

 

Estimate the value of Go at 400 K.
Go =3-978 kJ/mol
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