Search found 31 matches

by Neon
Thu Mar 28, 2024 1:56 am
Forum: Chemistry forum
Topic: Redox reactions
Replies: 5
Views: 39

Re: Redox reactions

Ok, but why did you write:
E2 = 0,535 + 0,059/2 *log( 1/(0,1)^2)
and no E2 = 0,535 - 0,059/2 *log( 1/(0,1)^2) ?
by Neon
Thu Mar 28, 2024 12:43 am
Forum: Chemistry forum
Topic: Redox reactions
Replies: 5
Views: 39

Re: Redox reactions

Thanks, but I have some questions: 1. Why did you use plus and not minus in the second Nernst equation (for iodine). 2. Why did you assume that the activity of elemental iodine is 1? Iodine could also dissolve a little. When I was solving this, I thought as if I wanted to calculate the voltage durin...
by Neon
Wed Mar 27, 2024 12:22 pm
Forum: Chemistry forum
Topic: Redox reactions
Replies: 5
Views: 39

Redox reactions

Please help: The standard electrode potential for the reduction of nitrate(V) ions to nitrate(III) ions is 0.940 V. The standard electrode potential for the reduction of iodine to iodide ions is 0.535 V. If we have a solution that has the same concentration of nitrate(V) and nitrate(III) ions and a ...
by Neon
Mon Mar 25, 2024 11:35 am
Forum: Chemistry forum
Topic: Redox reactions and standard electrode potentials
Replies: 1
Views: 28

Redox reactions and standard electrode potentials

Hello, please help me with the following matter: I have given the standard electrode potential for the reduction of silver triiodide to silver and three iodide ions. The value is -0.029 V. Then I have given other standard electrode potentials such as E0(H+/H2) = 0.000 V etc. The question is which of...
by Neon
Fri Mar 22, 2024 2:34 am
Forum: Chemistry forum
Topic: Liquid-liquid extraction of weak electrolytes
Replies: 1
Views: 38

Liquid-liquid extraction of weak electrolytes

Im asking for help:

Calculate the distribution coefficient D if the partition coefficient K = 50.0 for the benzene-water system if the pKb of the base (solute) is 5 and pH is 8.00.

Thank you!
by Neon
Sat Feb 10, 2024 10:54 am
Forum: Chemistry forum
Topic: Titration of mixture of KOH and K2CO3
Replies: 11
Views: 1250

Re: Titration of mixture of KOH and K2CO3

But still, if we consider the aliquot, the mass is too high.
by Neon
Sat Feb 10, 2024 1:13 am
Forum: Chemistry forum
Topic: Titration of mixture of KOH and K2CO3
Replies: 11
Views: 1250

Re: Titration of mixture of KOH and K2CO3

That's how I calculated it: c(HCl) = (6*0.1250)/(0.0357*214)= 0.09817 M n(K2CO3) = 0.0261*0.09817 = 0.002562 mol V(HCl for KOH) = 33.7 - 26.1 = 7.6 mL n(KOH) = 0.0076 * 0.09817 = 0.000746 mol m(K2CO3) = 0.002562 mol *138.21 g/mol * 5 = 1.7705 g 1.7705 g is much more than 0.7341 g. So where did I go ...
by Neon
Fri Feb 09, 2024 3:26 am
Forum: Chemistry forum
Topic: Titration of mixture of KOH and K2CO3
Replies: 11
Views: 1250

Titration of mixture of KOH and K2CO3

Weigh 0.7341 g of technical KOH, which also contains K2CO3, quantitatively transfer it to a 250 mL volumetric flask, dissolve and make up to the mark. Prepare two Erlenmeyer flasks, pipette 50 mL of the prepared solution into each, add the indicator phenolphthalein to the first, and methyl orange to...
by Neon
Fri Feb 02, 2024 3:02 pm
Forum: Chemistry forum
Topic: Electrochemistry
Replies: 3
Views: 1015

Re: Electrochemistry

I understood the task as if at the beginning we only have lead and H2SO4 and when they react PbSO4 is formed, and therefore the concentration of free SO4 2- ions must be less than 2 M. But this is obviously not the case and I understand it wrong. Can you please explain to me how to imagine this.
by Neon
Fri Feb 02, 2024 8:51 am
Forum: Chemistry forum
Topic: Electrochemistry
Replies: 3
Views: 1015

Electrochemistry

Please help me with this task, the result should be -0.366 V. I know how to come up with the result, but in the calculation I took into account that the concentration of sulfate ions is 2 M, which does not seem right to me. Calculate the potential of the lead electrode in 2 M H2SO4 if E0 = -0.126 V ...
by Neon
Sun Dec 17, 2023 7:53 am
Forum: Chemistry forum
Topic: Neutron activation analysis
Replies: 3
Views: 3366

Re: Neutron activation analysis

Determining the amount of mercury in hair. The basic method would be CVAAS, but I have to mention an alternative. I was thinking of taking NAA. I have to compare according to analysis time, detection limit, analysis type and other specifics.
by Neon
Sat Dec 16, 2023 11:12 am
Forum: Chemistry forum
Topic: Neutron activation analysis
Replies: 3
Views: 3366

Neutron activation analysis

Hi, do we need a calibration curve for NAA analysis or not? I also wonder how long this analysis takes?
Thank you!
by Neon
Sun Dec 03, 2023 2:17 am
Forum: Chemistry forum
Topic: Determination of Hg in human hair
Replies: 8
Views: 4644

Re: Determination of Hg in human hair

Thanks for the reply. I'm curious about one additional aspect of the hair sample processing. As I've read, the decomposition procedures are rather distinct, but because I've never done this before, I'm wondering if the decomposition with nitric acid and hydrogen peroxide is so good that no filtratio...
by Neon
Sat Dec 02, 2023 2:59 am
Forum: Chemistry forum
Topic: Determination of Hg in human hair
Replies: 8
Views: 4644

Determination of Hg in human hair

Hello, I have to write a term paper on the determination of mercury in human hair. I've read quite a few professional articles, but none describe the process in great detail. After reading everything, I somehow came to the conclusion that it would be best to use cold-vapor-atomic-absorption-spectome...
by Neon
Sat Oct 14, 2023 12:32 pm
Forum: Chemistry forum
Topic: Gravimetric determination of magnesium
Replies: 1
Views: 682

Gravimetric determination of magnesium

Hello,

can you please tell me how to write the chemical reaction that takes place between magnesium ion and (NH4)2HPO4 as a precipitating reagent.

Thank you.