Indicate whether Delta S and Delta H is positive or negative. Then indicate if the reaction is entropy driven, enthalpy driven or neither.
NaCl(s) + H2O(l) + Heat => NaCl (aq)
See my response to the question directly above this question. You know the reaction is endothermic.
Consider the following:
*When you dissolve NaCl in water, the mixture cools indicating an endothermic change. It leads to products with higher enthalpy.
*NaCl crystals are highly orderly structures which means that their entropy is low. As they dissolve in water they dissociate into randomly dispersed ions with an increase in entropy (disorder).
*A chemical or physical change tends to be spontaneous
(a) if it leads to products of lower enthalpy (exothermic change, or one with negative deltaH ),
(b) if it leads to greater disorder (higher entropy or positive deltaS )
Now you have everything you need to draw you own conclusions.
i would like to learn more about the last chapter of our text book study mate the chemical change
To determine whether ΔS (change in entropy) and ΔH (change in enthalpy) are positive or negative for a given reaction, we need to consider the overall changes in the system.
First, let's analyze the given reaction: NaCl(s) + H2O(l) + Heat → NaCl(aq)
1. ΔS (Entropy change):
Entropy generally measures the amount of disorder in a system. If the number of gas molecules increases, the distribution becomes more disorderly, resulting in an increase in entropy. On the other hand, if the number of gas molecules decreases, the distribution becomes more orderly, resulting in a decrease in entropy.
In this reaction, we see that solid NaCl (s) is dissolving in liquid water (H2O(l)). The dissolution process usually leads to an increase in entropy because the orderly arrangement of solid particles is broken, and the dissolved ions are free to move around in the solution. Therefore, ΔS is most likely positive.
2. ΔH (Enthalpy change):
Enthalpy refers to the heat energy absorbed or released during a reaction. Exothermic reactions release heat to the surroundings, while endothermic reactions absorb heat from the surroundings.
In this reaction, the presence of "Heat" on the right side of the equation indicates an exothermic process, meaning heat is being released. Consequently, the ΔH is negative in this case.
Now, let's determine if the reaction is entropy-driven, enthalpy-driven, or neither based on the signs of ΔS and ΔH:
Entropy-driven:
If ΔS is positive and ΔH is negative, the reaction is generally entropy-driven. In this reaction, since ΔS is likely positive and ΔH is negative, it suggests that the increase in entropy is the driving force for the reaction, making it entropy-driven.
To summarize:
- ΔS: Positive (increase in entropy)
- ΔH: Negative (exothermic release of heat)
- Reaction type: Entropy-driven
Please note that this analysis assumes ideal behavior and does not consider other factors like temperature or pressure, which may affect the overall trend.