May 15, 2024, 03:36:54 AM
Forum Rules: Read This Before Posting


Recent Posts

Pages: [1] 2 3 ... 10
1
High School Chemistry Forum / Re: Searle's bar experiment takes forever/inconclusive?
« Last post by Borek on Today at 03:22:34 AM »
Top be honest I have no idea what you mean. Temperatures can't be equal if one end is heated and the other cooled.

Experiment time is not defined, but you should take measurements till the system gets to thermal equilibrium - that is, consecutive temperature measurements produce identical results.
2
Organic Chemistry Forum / Re: Bromination
« Last post by Hunter2 on Today at 02:59:28 AM »
Better FeBr3 as catalyst in this case. Risk to get also Chloro Derivate if FeCl3 is used.
3
Organic Chemistry Forum / Re: Bromination
« Last post by rolnor on Today at 01:44:49 AM »

I think its straightforward to di-brominate benzoic acid, the dibromo acid is available on many vendors. You might need FeCl3 as catalyst.
4
High School Chemistry Forum / Searle's bar experiment takes forever/inconclusive?
« Last post by sd79812 on Yesterday at 03:36:09 PM »
Searle’s bar experiment measures thermal conductivity by comparing temperature differences near the heat source and at the ends. However, since the temperatures at the unheated end/heated end often equalize at the beginning/end, the experiment may seem to take an indefinite time to yield results because you can't divide by zero, and I know for a fact that fraction can't be zero so often.



5
Organic Chemistry Forum / Re: Bromination
« Last post by Hunter2 on Yesterday at 07:27:57 AM »
Benzoic acid to Di- Nitro Benzoic acid, reduce to Diaminobenzoic acid(ester), then Diazoting and Sandmeyer to Bromo Compound.
6
Organic Chemistry Forum / Bromination
« Last post by mujic on Yesterday at 07:12:28 AM »
I want to synthesize methyl 3,5-dibromobenzoate (3,5-dibromobenzoic acid methyl ester).

This can be synthesized from the corresponding benzoic acid, ester, or aldehyde, which are all meta- directing. However, they strongly deactivate the benzene ring and make bromination difficult. Even if the first bromination is achievable, i cannot find any papers on how to do the second one.

I don't have access to an already bromo- substituted benzene compound.

Is there an easier synthetic route? I am struggling in finding any papers for reference.

I am very new to Organic Chemistry and although it seems like an easy target I still find it extremely difficult.
7
High School Chemistry Forum / Re: Chemistry Lab help ASAP! Reaction between Sodium Thiosulfate & Iron(III) Nitrate
« Last post by Borek on Yesterday at 02:47:48 AM »
Quote from: mahiru on May 13, 2024, 08:35:12 PM
first of all, since I am not changing concentration, how do I find rate of reaction?

You can't. All you can do is to qualitatively state "this is faster, this is slower". For some applications this is perfectly enough though.

Quote
Also, I am having a hard time understanding what is happening.
CuSO4 was fastest (average of about 10.83 sec for the cross to appear)despite it being +2., and the other two (+1 and +3) were about the same to each other (around 56seconds). I don't understand the pattern, and what is affecting this.
can someone explain why CuSO4 was a better catalyst and why the other two didn't show much difference to each other? I have no clue what is going on and how exactly the catalysts impacted the reation...

You can't base the conclusion on a single run using just three metals. Way too many different factors.

Plus, using Fe(III) compound as a catalyst in the presence of the reacting Fe(III) compound sounds like a nonsense idea - you alrerady have an excess of the cation in the solution, no way to say if addition of a bit more produces catalytic effect.
8
High School Chemistry Forum / Chemistry Lab help ASAP! Reaction between Sodium Thiosulfate & Iron(III) Nitrate
« Last post by mahiru on May 13, 2024, 08:35:12 PM »
I am investigating how different transition metal catalysts (with different charges) affect the rate of reaction between Sodium thiosulfate and Iron(III) Nitrate. My catalysts were Ag(I)NO3, Cu(II)SO4, and Fe(III)Cl3. I observed the reaction from above and recorded the time it took for the cross at the bottom of the reaction became visible.

first of all, since I am not changing concentration, how do I find rate of reaction?

Also, I am having a hard time understanding what is happening.
CuSO4 was fastest (average of about 10.83 sec for the cross to appear)despite it being +2., and the other two (+1 and +3) were about the same to each other (around 56seconds). I don't understand the pattern, and what is affecting this.
can someone explain why CuSO4 was a better catalyst and why the other two didn't show much difference to each other? I have no clue what is going on and how exactly the catalysts impacted the reation...

Please help me. Thank you in advance.
9
Analytical Chemistry Forum / Re: Calculation of %Absorbance
« Last post by serotonin on May 13, 2024, 04:50:43 PM »
thanks very much!
10
Organic Chemistry Forum / Re: Essential Oil(s) in Rosemary
« Last post by Borek on May 13, 2024, 02:17:51 PM »
Quote from: rolnor on May 13, 2024, 12:37:12 PM
I gave chiralic a molesnack, nice help

Yes, nice answer to an 18 years old post , dug out by a newcomer necroposter, probably using ChatGPT to generate reasonably looking answer ;)
Pages: [1] 2 3 ... 10