Vinícius Godim
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Is there such a thing as a "minimal soap" molecule?
26 votes

It boils down to the definition of soap. Wikipedia defines a soap as the salt of a fatty acid. IUPAC claims the smallest fatty acid can be considered to have 4 carbons. Therefore the simplest soap ...

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What drives a molecule/atom towards stability?
8 votes

It boils down to thermodynamics. No, molecules do not possess intelligence. But they respect the laws of thermodynamics, which in a general look state: Energy of a closed system is constant. The ...

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How to define equivalents here
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7 votes

Number of equivalents and normality are out-of-date concepts in chemistry. For acids, they are just like number of mols and molar concentration (or molarity), with an extra factor indicating how many ...

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Will NaOH react with ethanol?
5 votes

Just because one can write down the reaction equation (as you have read in those websites) doesn't mean it takes place to any considerable extent. Yes, ethanol and NaOH do theoretically react as in $\...

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What is the difference between a radical and a neutral alone atom?
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5 votes

A chlorine radical and a chlorine atom are effectively the same thing. This does not mean that "radical" and "atom" are interchangeable as jargons. They are used in fairly particular contexts, namely ...

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Determine vmax and enzyme concentration (Michaelis–Menten)
4 votes

Michaelis-Menten kinetics is given by $$V = V_{\max} \frac{S}{K_M + S}$$ Taking the inverse of both sides to linearise the equation, $$\frac{1}{V} = \frac{1}{V_\max} +\frac{K_M}{V_{\max} S}$$ Taking $...

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Why do colligative properties depend only on number of solute particles?
4 votes

It's a lie. Colligative properties do depend on the chemical nature of the solute and solvent - their interaction. The trick is: an ideal solution, in which the solute-solute intermolecular forces and ...

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How to use a modified Peng-Robinson equation to calculate a density?
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4 votes

According to this source: The popular EoSs such as Soave-Redlich-Kwong (SRK) [1] and Peng-Robinson (PR) [2] predict liquid density with an average absolute error of about 8%, much higher than ...

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Is there a connection between M1V1=M2V2 and Boyle’s Law?
3 votes

Yes, they are related. The first comes directly from the conservation of number of moles of the solute in a dilution, $$n_1 = n_2 $$ Since $n = MV$, $$M_1 V_1 = M_2 V_2$$ The second is related to ...

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Derive expression for heat flow from oil bath to metal sphere
Accepted answer
3 votes

Newton's law of cooling is $$q = A h (T_0 - T_S )$$ With the area of the sphere being $$A = 4 \pi R^2$$

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Why are ammonium chloride and ammonium hydroxide used in calcium salt detection?
Accepted answer
3 votes

You want to fix the carbon in solution so it doesn't volatize as $\ce{CO2}$, since the equilibrium $$\ce{H2CO3 <=> CO2 + H2O}$$ favours the product side. By adding a base ($\ce{NH4OH}$), you ...

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Not able to match the number of components in a system with the "species-approach" to the Gibbs phase rule
2 votes

The Gibbs phase rule for reacting systems is $$F = 2 - \pi + N - r - s$$ Where $F$ is number of degrees of freedom, $\pi$ is number of phases, $N$ is the number of components, $r$ the number of ...

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Concentration of Hydrogen Ions
2 votes

Since $\ce{NaOH}$ is a strong base, the pH can be directly calculated from the analytic concentration (1M): $\ce{pOH} = -\log\ce{[OH-]} = -\log(1) = 0 $ $\ce{pH} = 14 - \ce{pOH} = 14 - 0 = 14$ For ...

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Does Langmuir model predict evaporation rates?
Accepted answer
2 votes

That most likely refers to the Hertz-Knudsen equation, also known as Knudsen-Langmuir equation. It is the most simplified model of evaporation in which no discussion is given into the diffusivity and ...

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Xylan vs. Teflon for non-stick food pans?
2 votes

Both Xylan and Teflon are chemically polytetrafluoroethylene. But a polymer just by name can mean a lot of different things if you consider the structure/arrangement, additives and impurities. These ...

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Hamiltonian 2nd positional derivative analogous to acceleration?
2 votes

If you really want a classical physics comparison, a second spatial derivative comes up in physical problems in the context of diffusion systems. The 1-D heat equation for example $$\frac{\partial T}{...

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Simplest way to convert glucose into water and carbon dioxide other than burning?
2 votes

I'd suggest you read into the Fenton process. Using an iron catalyst with hydrogen peroxide will break down (potentially) any organic matter into $\ce{CO2}$ and $\ce{H2O}$ within minutes or hours. The ...

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Do solids in a solution also apply partial pressure? If yes, can this be used as an intuitive explanation for osmosis?
1 votes

The vapor pressure of ions like $\ce{Na+}$ and $\ce{Cl-}$ is effectively zero compared to the vapor pressure of water, so your equation is essentially correct though $p_{\mathrm{total}} = p_{\ce{H2O}}$...

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Reason for enthalpy being non-zero at constant temperature
1 votes

For a multicomponent reactive system you would rather write the enthalpy differential as $$ d(nH) = \left(\frac{\partial (nH)}{\partial T}\right)_{P,n_i}dT + \left(\frac{\partial (nH)}{\partial P}\...

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When a bond is formed between an electophile and a nucleophile, they both lose energy and become more stable right?
Accepted answer
1 votes

In the context of the picture provided, it seems just a matter of language choice. When energy is lost, it is gained somewhere else because of conservation of energy. So a change in energy ...

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Does dissolving something in water change the specific heat of the solution?
1 votes

If you were adding two liquids ideally, that is, assuming that the mixing occurs without any change in enthalpy - which occurs for chemically similar substances, then yes, the heat capacity of the ...

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Is the Haber Process here proceeding at positive Gibbs free energy change?
1 votes

The tendency of a reaction to proceed in a certain direction depends on the state of the concentration of each reactant. If you calculate the standard Gibbs free energy of the reaction and it's a ...

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Why does acetic acid (CH3COOH) conduct electricity the worst in comparison to HBr, HCOONa and NaNO3
1 votes

It's because acetic acid won't fully ionize in solution, it's a weak acid. Less ionization means less total amount of ions in solution, which implies lower electrical conductivity. The wording of the ...

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Pressure dependency in Haber Bosch ammonia synthesis
1 votes

According to Le Chatelier's principle, a pressure increase should result in the equilibrium shifting to the right, but it should not - at least to first approximation - affect the equilibrium constant....

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Is it possible to solve the equation for the diffusion of gas through a sphere analytically by applying e.g. "combination of variables"?
1 votes

Yes. Let's improve the wording here: that is not just an expression, it's the definition of a dimensionless variable that eases the understanding of the solution of the transient diffusion is a semi-...

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Is volume expansion possible upon dissolution of solute?
1 votes

Yes. In thermodynamic jargon, the onset of a change in volume under dissolution is known as an excess volume. If the solution takes up less volume than its constituent parts it is said to have a ...

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Finding required drug concentration given Kdiss
1 votes

Chemical reaction is $$\ce{D1 + E <=> ED1}$$ Initial concentrations: $[\ce{D1}]_\textrm{tot}; \quad [\ce{E}]_\textrm{tot}; \quad 0$. If $X$ percent of $E$ "reacts", then stoichiometry tells ...

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How can Phosphate be charged at -3?
Accepted answer
1 votes

All the oxygen atoms have the same oxidation number $-2$. The charge balance then tells that the phosphorous atom has be at a state $+5$. That's the entire story.

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Clarifying understanding of shifting equilibrium in dynamic systems:
1 votes

Say you have the reaction A -> B. Standard notion is that increasing concentration of reactant shifts equation to the right but that can obviously not be the case here. Explanation: Take two ...

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Vapour-Liquid Equilibrium
1 votes

Absolutely not. It means that for the mixture to be boiling at 110°C, it must not contain any benzene.

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