Unanswered Questions
304 questions with no upvoted or accepted answers
7
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0
answers
135
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Metal hydrolysis and equilbrium constants from stability constants
Problem: I want to create minimum solubility plots for a series of metal hydrolysis species against pH (below). But I cannot reconcile literature stability constants and equilibrium constants.
Context:...
- 123
6
votes
0
answers
171
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Which xylenes, if any, are immiscible with DMSO?
"Xylene" is reported to be immiscible with dimethyl sulfoxide (DMSO), according to a few solvent miscibility tables found online (chart 1, chart 2, chart 3). I have tried to locate some ...
- 782
6
votes
0
answers
67
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Using Le Chatelier's Principle to Change Mechanical Energy to Chemical Energy
I was interested in an application of Le Chatelier's principle, where an increase in pressure could result in a decrease in the moles of gas.
In particular, a situation where when the pressure ...
- 169
6
votes
0
answers
775
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How can copper(II) sulfate crystallize outside a glass vial?
I'm making copper sulfate crystals in glasses. Within a few weeks, the copper sulfate seems to crystallize both inside and outside the glass:
(A few weeks after making a new solution)
(Yet another ...
- 17.5k
5
votes
0
answers
479
views
Why does pKw first decrease but eventually increase when temperature rises?
I understand the initial decrease in pKw.
$\ce{Heat + H2O (l) <=> H+ (aq) + OH- (aq)}$
Temperature increases, reaction shifts to the right, so
$\ce{H+} \text{ and } \ce{OH}$ ...
- 1
5
votes
0
answers
98
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Equations Used in Isothermal Titration Calorimetry
I have been attempting to understand and derive the formulas used for ITC which can be found here starting on page 310. I am particularly interested in the single set of identical sites. To first ...
- 807
5
votes
0
answers
5k
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Should I round an experimentally determined reaction order to an integer?
For a lab experiment I did, I calculated the reaction order for one of the reactants using data from two trials, both rates, and the concentration of that reactant during each.
$$
\frac{\text{Rate}_1}{...
- 6,801
5
votes
1
answer
553
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What does the equilibrium constant mean for reactions with very small concentrations?
When you calculate the equilibrium constant for a reaction with a higher concentration of reactants, the answer is fairly intuitive. For example, for the reaction:
$$\ce{A + B <=> C}$$
when we ...
- 22.5k
4
votes
0
answers
84
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Regarding Ellingham diagrams
In my textbook, the following information is given about Ellingham diagram:
The interpretation of $\ce{\Delta_rG^\circ}$ is based on ${K}$ ($\ce{\Delta G^\circ = -RTlnK}$). Thus it is presumed that ...
- 549
4
votes
0
answers
74
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Decomposition of Hydrogen Peroxide Catalysed by Potassium Iodide in Basic Solution
As part of my high school project, I had to measure the initial rate of decomposition of hydrogen peroxide catalysed by potassium iodide at different pHs. At higher pHs (alkaline conditions), I found ...
- 41
4
votes
0
answers
82
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Why does equilibrium for the addition of the Claisen enolate to an ester not favor the product?
I am currently reading chapter 26 of Clayden's Organic Chemistry, and a diagram for the elementary steps of the Claisen condensation with ethyl acetate in ethoxide is provided. It is obvious why the ...
- 2,010
4
votes
0
answers
87
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Is entropy maximum in equilibrium?
Usually, in the context of non-equilibrium thermodynamics, it is said that entropy achieves a maximum in equilibrium, so the Taylor series expansion of entropy around the equilibrium state as a ...
- 686
4
votes
0
answers
248
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How are σ+ values in Hammett Plots calculated?
First of all, I know a similar question has already been asked & answered about σ values in general, however, I am not 100 % sure this answer is correct for the following situation.
So for the σ ...
- 17.5k
4
votes
0
answers
88
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Computing the turbulent flame length
There is a problem I found online for practice that I cannot solve:
Problem
Methane, $\ce{CH4}$, emerges from a $1\ \mathrm{cm}$ diameter nozzle
at a rate of $120\ \mathrm{cm^3/s}$ and a mole ...
- 183
4
votes
0
answers
646
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Validity of the equation K_eq = ratio of rate constants of forward and reverse reactions
If we have a multi-step reaction (which involves more than one step to reach the products; a complex reaction, one may say), then is the following equation valid?
$$K_\mathrm{eq} = \frac{K_\mathrm{...
- 38.4k