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If water H2O is polar and oxygen O2 non-polar how can there be dissolved oxygen in water?
The simple answer is that most everything happens at least a little bit. The reason why is EQUILIBRIUM. You are correct---water is polar and oxygen is non-polar. The water molecules have great hydrogen bonding and dipole-dipole interactions with each other that the oxygen molecules cannot replace, and so it will take energy or ENTHALPY for oxygen to mix its way into the water. So the process is ENDOTHERMIC and hence unfavorable. However, when you dissolve oxygen in water, you get disorder---something that scientists quantify by talking about a solution's ENTROPY. It is favorable for entropy to increase, and in this case the entropy of the water solution would go up if you were to be able to squeeze some water molecules in there. So entropy and enthalpy are at odds for this reaction. Enthalpy is unfavorable, entropy is favorable. In situations like that systems will reach a state of equilibrium in which the reaction partially occurs. How much will depend on the relative sizes of the entropy and enthalpy changes.
Calculate the entropy of vaporization per mole of ethanol Given enthalpy change is 109.8 JK-1 mol-1 and boiling point of ethanol is 78.50C?
OK.With entalpy od vaporization and temperature of vaporization is very easy to calculate entropy of vaporization of etanol.So the equation to calculate this is:Delta_S=-Delta_H/TbWhere:Delta_S= Entropy of vaporizationDelta_H=Entalpy of vaporizationTb= Normal Boiling point temperatureSo the Delta_S become:Delta_S=-(-109000.8)/(78.5+273)Delta_S=310.1 J.mol-1.K-1
Why NaCl is very soluble but not CaO is only slightly soluble in water?
Its all to do with enthlapy and entropy. Anything which is soluble usually has a negative standard enthlapy of solution - the energy involved when 1 mole of solute dissolves in a solvent to give an infinately dilute solution. However, NaCl has a slightly positive enthalpy of solution, yet it dissolves. The reason for this is entropy - the change in the amount of disorder. When NaCl dissolves in solution, there is more chaos, more molecules within the solution. Any process that has a large positive entropy change will be favourable - spontaneous and can occur (reaction will 'go'). However, with CaO, the Ca2+ formed in solution has a high affinity (attraction to) for water molecules, hence a lot of water molecules are arranged orderly - less chaos and hence a negative entropy. This should in effect make the compound insoluble, however, the slight solubility is due to it still having a negative enthalpy change of solution - hence despite entropy it is still slightly soluble. (You may be asking how is dissolving CaO possible if entropy is negative? The entropy of the system maybe negative, but the entropy of the surroundings is positive (dissolving gives out heat - exothermic), hence the overall entropy (sum of both entropies) is positive and the reaction will 'go'.
What is the entropy change for the vaporization of 1.8 mol H2O at 100 degrees Celsius and 1 ATM?
I think you meant to use the word enthalpy. Enthalpy refers to the flow of heat, while entropy means the "randomness" of a system.Because The water is already at its boiling point (100o C), it doesn't need to be heated any more to start boiling. To find out how much energy it takes, you'll need to look up the molar heat of vaporization. Simply put, this is the amount of energy it takes to boil one mol of a substance. Water's molar heat of vaporization is 40.2 kJ/mol.Now, all we need to do is multiply:1.8mol * 40.2kJ/mol = 72kJ(Note: The 1 atm is important because that is the pressure at which water's boiling point is 100oC. If there was any less pressure, it would have already boiled. If there was more pressure, it would have to heat up to the new boiling point, then use 72kJ to boil.)
Which physical state of nitrogen has the highest entropy?
The gas phase. That is true of any substance. Gases, because they are free to move about the entire volume of any container have much more entropy than either liquid or solids (and liquids have more than solids). The more ways the atoms are free to move around, the more entropy they have.
Is Delta S is the change in enthalpy a measure of randomness?
No, ΔS (change in entropy) and ΔH (change in enthalpy) are not measurements of randomness. Entropy is a measure of the disorder or randomness in a system, while enthalpy is a measure of the heat energy of a system. The change in entropy and enthalpy can be related in chemical reactions to determine the overall spontaneity of the process.
What characteristics of a substance is NOT affected by enthalpy and entropy?
Pressure is not affected by enthalpy and entropy.pressure
When graphing enthalpy and entropy what variables are included?
Temperature and energy are two of the variables included when graphing enthalpy and entropy. Enthalpy is made up of the energy, pressure, and volume of a system. Entropy is a way to determine the different ways energy can be arranged.
Does the entropy of a solid increases when its dissolved in a solvent?
Why does the entropy of a solid increases when it is dissolved in a solvent
What is the definition of enthalpy and entropy?
Enthalpy is the amount of energy released or used when kept at a constant pressure. Entropy refers to the unavailable energy within a system, which is also a measure of the problems within the system.
What could make delta G become negative at a given enthalpy and entropy?
For delta G to become negative at a given enthalpy and entropy, the process must be spontaneous. This can happen when the increase in entropy is large enough to overcome the positive enthalpy, leading to a negative overall Gibbs free energy. This typically occurs at higher temperatures where entropy effects dominate.
What is the relationship between enthalpy, entropy, and free energy in a chemical reaction?
In a chemical reaction, enthalpy, entropy, and free energy are related. Enthalpy is the heat energy exchanged during a reaction, entropy is the measure of disorder or randomness, and free energy is the energy available to do work. The relationship between these three factors is described by the Gibbs free energy equation: G H - TS, where G is the change in free energy, H is the change in enthalpy, S is the change in entropy, and T is the temperature in Kelvin. This equation shows that for a reaction to be spontaneous, the change in free energy must be negative, meaning that the enthalpy change and entropy change must work together in the right direction.
How do you know if a reaction is entropy driven enthalpy driven or driven by both enthalpy and energy?
If the ∆H is positive and the ∆S is positive, then the reaction is entropy driven. If the ∆H is negative and the ∆S is negative, then the reaction is enthalpy driven. If ∆H is positive and ∆S is negative, then the reaction is driven by neither of these. If ∆H is negative and ∆S is positive, then the reaction is driven by both of these.
What could make G become negative at a given enthalpy and entropy?
Changing the temperature
How does gibbs energy relate to the changes in ethalpy and ethropy?
Gibbs energy accounts for both enthalpy (heat) and entropy (disorder) in a system. A reaction will be spontaneous if the Gibbs energy change is negative, which occurs when enthalpy is negative (exothermic) and/or entropy is positive (increased disorder). The relationship between Gibbs energy, enthalpy, and entropy is described by the equation ΔG = ΔH - TΔS, where T is temperature in Kelvin.
What is the relationship between the enthalpy h and entropy s of a reaction that is spontaneous at higher temperatures but not at lower temperatures?
The relationship between enthalpy (H) and entropy (S) is described by the Gibbs free energy equation, ΔG = ΔH - TΔS, where ΔG is the change in Gibbs free energy, ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. For a reaction to be spontaneous at higher temperatures but not at lower temperatures, the entropy term (TΔS) must dominate over the enthalpy term (ΔH) in the Gibbs free energy equation. This suggests that the increase in entropy with temperature plays a more significant role in driving the reaction towards spontaneity than the enthalpy change.
What are the units of enthalpy?
The units for entropy are joules per kelvin (J K-1)
