Explanation:
Sublimation is defined as a process in which solid state of a substance directly changes into vapor or gaseous state without undergoing liquid phase.
For example, naphthalene balls show sublimation at room temperature.
As this process does not cause any change in chemical composition of a substance. Hence, it is known as a physical process.
Similarly, when 
sublimes readily at 
. This shows change in physical state of carbon dioxide is taking place, i.e, from solid to gaseous phase.
Thus, we can conclude that when sublimes readily at then it means physical properties are usually associated with a compound that undergoes this kind of change.
5.61 x 10^8 (this might not be entirely right, haven’t used scientific notation in a while)
<u>Answer:</u> The 
for the reaction is 51.8 kJ.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The chemical equation for the reaction of carbon and water follows:
The intermediate balanced chemical reaction are:
(1) 
( × 2)
(2) 
( × 2)
(3) 
The expression for enthalpy of the reaction follows:
![\Delta H^o_{rxn}=[2\times \Delta H_1]+[2\times \Delta H_2]+[1\times (-\Delta H_3)]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B2%5Ctimes%20%5CDelta%20H_1%5D%2B%5B2%5Ctimes%20%5CDelta%20H_2%5D%2B%5B1%5Ctimes%20%28-%5CDelta%20H_3%29%5D)
Putting values in above equation, we get:
![\Delta H^o_{rxn}=[(2\times (-393.7))+(2\times (-285.9))+(1\times -(-1411))]=51.8kJ](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B%282%5Ctimes%20%28-393.7%29%29%2B%282%5Ctimes%20%28-285.9%29%29%2B%281%5Ctimes%20-%28-1411%29%29%5D%3D51.8kJ)
Hence, the for the reaction is 51.8 kJ.
This will be classified as light on the API scale due to the large percentage of lighter fractions such as paraffins and naphthenes.
Answer:
The determination of the nature of the combination of the two separate materials in the original material that looks pure is based on the characteristic of the change process they undergo to become two separate materials.
Therefore, they can know if they initially had a mixture or a compound by the following steps;
1) If the two separated materials can be easily remixed to form the original material, then they likely have a mixture of the two separate materials
2) If the process that results in the formation of the two separate materials, involves the absorption or evolves heat or other forms of energy, then the original substance was a compound
3) If the two newly formed materials is seen to be a permanent change, then the original material was a compound
Explanation:
