Answer : The standard enthalpy of formation of ethylene is, 51.8 kJ/mole
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation reaction of 
will be,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
(3) 
Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equations, we get :
(1) 
(2) 
(3) 
The expression for enthalpy of formation of will be,
Therefore, the standard enthalpy of formation of ethylene is, 51.8 kJ/mole
10) Arsenic is a chemical agent which was used in preserving dead bodies in the past. It is mainly a formaldehyde mixture with coloring agents to give a dead body the look of life. Sylvester was a third mummy that was embalmed with arsenic in the late 1800s and is now on exhibit at Ye Olde Curiosity Shop in Seattle, Washington. His mummified body showed an extremely unusual since the remains weighed approximately 80 lbs when a body is composed of 70-80% water, after dehydration, the weight should be about 20-30% the premortem weight. The solution was also used during Civil War to preserve dead bodies <span>as the dead were being shipped home from the battlefield.
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9) R<span>esearch can yield dates when certain plants/animals became domesticated and entered the standard diets of people, meaning you would not see masses eating beef before the cow became domesticated. To further this you can look at when a specific food was introduced into the diets of people in the geographic area of the person you are studying. </span>
Answer:
If mass remains the same while the volume of a substance changes, the density of the substance will also change.
A cation will not replace an anion in a compound because the two positively-charged ions will repel each other.
<h3>Ions</h3>
Ions are atoms or group of atoms possessing an electrical charge.
- Positively-charged ions are known as cations.
- Negatively-charged ions are known as anions.
<h3>Ionic compounds</h3>
Ionic compounds are compounds which are composed of oppositely charged ions held together by strong electrostatic forces of attraction between the oppositely charged ions.
- From law of electrostatics, like charges repel and unlike charges attract.
If a cation replaces an anion, the compound would have two l positive charges which will repel each other.
Therefore, a cation will not replace an anion in a compound because the two positively-charged ions will repel each other.
Learn more about ions and electrostatics at: brainly.com/question/13690700
Answer:
Experiment, analysis, research, purpose, hypothesis and conclusion.
