All Questions
Tagged with aqueous-solution thermodynamics
37
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Estimation methods for temperature evolution of a high $\Delta H_{mix}$ dilution ($\ce{KOH}$ in water)
Question up front: Can temperature evolution in solutions be short-hand-estimated by simple state based calculations - with reasonable expectations of precision? (+/- 10° C)
I am trying to calculate ...
- 2,805
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Freezing of a beverage
I am trying to generally describe the process of freezing beer and how the different ingredients influence the freezing process. My general approach right now is to observe a beer as 90% water and 10% ...
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visualization problem of dilution of enthalpy $\Delta_{dil} H$ data with different initial concentrations
description
I have a question about the $m_f$ vs. $\Delta_{\text{dil}} H$ plot in some experimental studies.
For example, the dilution-of-enthalpy data at 300 °C with two initial concetration ($m_i$) ...
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2
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Why do we call salts such as AgCl sparingly soluble?
Though we use the term practically insoluble for salts like $\ce{AgCl}$ in inorganic chemistry, we preferably call them "sparingly" soluble salts in physical chemistry seeing their tiny ...
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Hydration vs Dissolution
While revising Thermodynamics and Thermochemistry from revision material published by Arihant publications I encountered the following mentioned statement.
During dissolution, the physical state of ...
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Is it the solution energy or the reduction potentials (or both) that drives a galvanic cell?
I have received conflicting explanations for why the redox reaction in a galvanic cell occurs.
Explanation 1:
Some say that it occurs because the anodic metal dissolves more easily than the cathodic ...
user108214
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Mechanistic explanation of salt lowering temperature of ice slush
As we all know, adding salt to ice water lowers its temperature.
I've read plenty of system-level accounts of energy balances, enthalpies, vapor pressures, phase equilibria and freezing points—I ...
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Computing enthalpy of formation of dissolved gas from its enthalpy of dissolution
Provided that I know the enthalpy of formation $\Delta H_f^0(X_{g})$ of a substance $X$ in gas phase and its enthalpy of dissolution $\Delta H^0_{sol}(X)$ in the same conditions, considering that the ...
- 306
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Why does silver (I) have a larger lattice enthalpy and hydration enthalpy than sodium?
The ionic radius of the $\ce{Ag^+}$ ion is $129$ pm, and that of the $\ce{Na^+}$ ion is $116$ pm.
Since the sodium ion is smaller than the silver ion, it makes sense that it has a stronger polarizing ...
- 2,109
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Does adding solutes to water alter its triple point? [closed]
Does adding solutes to water alter its triple point? If yes, how do we find the new temperature and pressure of this point?
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Is it appropriate to approximate solute particles in a dilute solution as an ideal gas?
I was studying osmosis and I came across the formula for osmotic pressure. I decided to see the derivation for osmotic pressure in a dilute solution. The derivation involved an equation involving the ...
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How to measure quantities at standard state when this state is a hypothetical one?
Consider the reaction
$$\ce{A(g) + H2O(l) <=> B(aq) + C(g)}$$
If all gases and solutions were ideal, the standard state would be pure water, the solute B at a concentration of 1 M, the gases A ...
- 41.2k
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Is the change in enthalpy (ΔH) for dissolution of urea in water positive or negative?
To test the properties of a fertilizer, $\pu{15.0g}$ of urea, $\ce{NH2CONH2_{(s)}}$, is dissolved in $\pu{150 mL}$ of water in a simple calorimeter. A temperature change from $\pu{20.6^\circ C}$ to $\...
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Is the water in an aqueous solution undergoing a reaction considered part of the system or surroundings?
System: In chemistry, a system is a chemical reaction. A system operates within its surroundings. Energy can move between the two.
Surroundings: The environment around a particular chemical reaction....
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1
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Insoluble salts and Gibbs free energy
Is it true that according to gibbs free energy equation, insoluble salts such as AgCl don't dissolve because the process would be too endothermic? The right side of the equation, TΔS, would have to be ...
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Is the crystallization process of aqueous solutions of substances such as lithium chloride endothermic?
$\ce{LiCl}$ has an enthalpy of solution of $\pu{-37.1 kJ/mol}$, so its dissolution process is exothermic. Does this mean that it's crystallization process is exothermic? I'm asking since I've looked ...
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In a reaction between Calcium Ammonium Nitrate or Urea with water, does Nitrogen Content and Purity affect how cold the solution gets?
Recently, I bought an ice pack that contained Calcium Ammonium Nitrate, and realized that it really didn't get cold. I came to the conclusion that perhaps Urea is more effective, yet it is still ...
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Predicting the vapor pressure of water ammonia solution
I am working on a project that involves the compressors for a vapor compression refrigeration cycle of R717 (ammonia) and came across something that has been boggling my mind a little bit for no good ...
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Volume change of solute addition to solvent
When making and manipulating high concentration stock solutions of sugar excipients, is there a way to predict the corresponding volume effect that occurs? I am asking in order to be able to create ...
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391
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Sodium Silicide (NaSi) Synthesis, Reversability
I'm trying to understand a) the reaction that would produce $\ce{NaSi}$ from $\ce{Na}$ and $\ce{Si}$, as well as how to reverse the reaction of $\ce{NaSi}$ with $\ce{H2O}$. The product of the latter ...
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How do hydrogen bonds break the ionic bonds of a crystal lattice? [duplicate]
In the case of water dissolving sodium chloride. I was under the impression that hydrogen bonds were much weaker than the ionic bonds in sodium chloride, so how do they overcome the ionic bond ...
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Osmotic pressure and Raoult's law co-relation?
Consider two compartments A and B joined. A contains pure water. B contains brine (dilute). Consider the Vant Hoff factor ($i$).
Obviously pressure over B is less than over A.
We also know that the ...
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How do I turn room temperature water into boiling water for drinking using an chemical/additive? [closed]
I am trying to create instant boiling water using a chemical of sorts, so that it can be consumed by a human. For example; someone could make tea without a kettle or any available water heating ...
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2
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635
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Why do increasing concentrations of zinc chloride not linearly decrease the freezing point?
I did an experiment on how different concentrations of $\ce{ZnCl2}$ affect the freezing point of demi water. My results were that till a concentration of about $10\ \mathrm{mol\,dm^{-3}}$ the freezing ...
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Hydrogen Peroxide Heat of Dilution
Based on some data here, I am getting the heat of dilution of 100% $\ce{H2O2}$ as approx. 1100 cal/mole.
That's about 4.6 kJ/mol if I did my math right.
Is this a correct value? Seems too low to ...
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How does increasing the ionic strength of an aqueous solution decrease the activity coefficient?
Activity is a new concept for me, and I am having a little bit of trouble understanding it.
For the equation:
$$\ce{aA + bB<=>cC + dD}$$
$$K_c= \frac{[\ce{A}]^a[\ce{B}]^b}{[\ce{C}]^c[\ce{D}]^...
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Why is lithium bromide used in absorption refrigerators?
Lithium bromide refrigerator
Why is lithium bromide used in absorption refrigerators? It is more expensive than sodium chloride. The wikipedia article on lithium bromide says it is extremely ...
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Is the dissolution of sodium acetate trihydate endothermic?
Sodium acetate trihydrate dissolves in water to its constituent ions:
$$\ce{NaOAc.3H2O (s) ->[H2O] Na+ (aq) + OAc- (aq) + 3H2O (l)}$$
The crystallisation of sodium acetate from a supersaturated ...
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Which formula is correct for calculating the heat of dissolution?
I want to calculate the energy change when a solute is dissolved in water. I know that I can achieve this by using the equation $q=mc \Delta T$. My question is does the mass ($m$) change with the ...
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Can we determine apriori the volume of solvent in an electrolyte
Suppose I would like to create a one molar solution of NaCl in water. The molar concentration is defined as
$c_i=\frac{n_i}{V} $
$n_i=1$ in this case. I need to take 58.5 grams of NaCl (atomic ...
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Is 4-nitrobenzaldehyde or 4-aminobenzaldehyde more likely to be hydrated?
Of 4-nitrobenzaldehyde and 4-aminobenzaldehyde, which has the higher $\ce{K_{eq}}$ of hydration?
$\qquad \qquad$
Steric factors can likely be ignored in this problem since we are dealing with ...
- 19k
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Thermodynamics behind Deliquescence?
The phenomenon of deliquescence wherein a water soluble substance absorbs water from atmosphere and dissolve in it forming a saturated solution, has thermodynamic roots. I have read the fact that the ...
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Why do salts such as NaCl dissolve?
If we look at solubility of salts in water, we are told that they disassociate, because the positive $\ce{Na}$ ion is attracted to the partially negative oxygen in water and the negative $\ce{Cl}$ is ...
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Azeotropes and separation by distillation?
I have just recently learnt the theory of fractional and normal distillations and the basics of maximum and minimum boiling azeotropes.
Most books say that the components of the mixture forming an ...
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How is hydration free energy of a solute measured experimentally?
I am reading a paper (Shirts, M. R.; and Pitera, J. W. and Swope, W. C. and Pande, V. S. J. Chem. Phys. 2003, 119, 5740-5761). Near the beginning of the paper (page 5745), the authors state:
...
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Is there a way to calculate how fast water will cool?
Is there a way to calculate how fast water will cool if you know the water's starting temperature and temperature of the environment that you put it in, such as a freezer?
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Deliquescence/efflorescence: How can I convert between salt concentration and RH?
I am looking at two phase diagrams, one has axes of $T$ and $\%\ce{MgClO4}$ in a $\ce{H2O-MgClO4}$ mix, and the other has axes of $T$ and relative humidity. The authors of the second phase diagram say ...
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