Answer:
Atoms are neither created or destroyed.
Explanation:
The end result of a chemical change does not create or destroy any atoms. Matter cannot be created or destroyed, meaning the same amount of atoms exist before and after the change.
Answer:
D is the correct answer.
Explanation:
I took the test on A pex. Everyone make sure you look at your answers. They are NOT always in the same order.
Answer:
Temperature required = 923K
Explanation:
The question is incomplete as there are some details that has to be given. details like the values of the standard enthalpies and entropies of the reactants and product as this is needed to calculate the actual value of the standard enthalpies and standard entropies of the reaction. I was able to get those values from literature and then calculated what needs to be calculated.
From there, I was able to use the equation that shows the relationship between, gibb's free energy, enthalpy, entropy and temperature. The necessary mathematical manipulation were done and the values were plugged in to get the temperature required to make the reaction spontaneous.
A few notes on the Gibb's free energy.
The Gibb's free energy also referred to as the gibb's function represented with letter G. it is the amount of useful work obtained from a system at constant temperature and pressure. The standard gibb's free energy on the other hand is a state function represented as Delta-G, as it depends on the initial and final states of the system.
The spontaneity of a reaction is explained by the standard gibb's free energy.
- If Delta-G = -ve ( the reaction is spontaneous)
- if Delta -G = +ve ( the reaction is non-spontaneous)
- if Delta-G = 0 ( the reaction is at equilibrium)
The step by step calculations is done as shown in the attachment.
3)
It has more surface area to react with
Answer:
Substances can change phase—often because of a temperature change. At low temperatures, most substances are solid; as the temperature increases, they become liquid; at higher temperatures still, they become gaseous.
The process of a solid becoming a liquid is called melting. (an older term that you may see sometimes is fusion). The opposite process, a liquid becoming a solid, is called solidification. For any pure substance, the temperature at which melting occurs—known as the melting point—is a characteristic of that substance. It requires energy for a solid to melt into a liquid. Every pure substance has a certain amount of energy it needs to change from a solid to a liquid. This amount is called the enthalpy of fusion (or heat of fusion) of the substance, represented as ΔHfus. Some ΔHfus values are listed in Table 10.2 “Enthalpies of Fusion for Various Substances”; it is assumed that these values are for the melting point of the substance. Note that the unit of ΔHfus is kilojoules per mole, so we need to know the quantity of material to know how much energy is involved. The ΔHfus is always tabulated as a positive number. However, it can be used for both the melting and the solidification processes as long as you keep in mind that melting is always endothermic (so ΔH will be positive), while solidification is always exothermic (so ΔH will be negative).
