Answer : The standard enthalpy of formation of ethylene is, 52.4 kJ
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 equation, we get :
(1) 
(2) 
(3) 
The expression for enthalpy of formation of will be,
Therefore, the standard enthalpy of formation of ethylene is, 52.4 kJ
Answer:
C. Fluorine because the model has 9 protons which is represented by the atomic number
Explanation:
We usually identify an element by the number of protons in them. The number of protons is the atomic number of an atom.
- Every atom has a specific number of protons in them.
- This number of protons is the atomic number.
- According to the periodic law, atoms are arranged on the periodic table based on their atomic number.
- The given fluorine atom has 9 protons which represents the atomic number of the atom.
- This way, the given number clearly shows the right model for identifying the chemical specie.
There are four states of matter, solid, liquid, gas and plasma. Their formation is as when solid is heated it converts into liquid, liquid on heating converts into gases and gases on heating converts into plasma.
Plasma:
Plasma is the fourth state of matter. It is the highest energy state of matter.
Composition:
Plasma is made up of negatively charged and positively charged particles.
Result:
The answer to your question is Plasma.
Answer:
this isn't immediately clear, it can be seen in ... CO2? 1. 6.0 × 10−23 g. 2. 44 g. 3. 7.31 × 10−23 g correct. 4. 6.0 × 10. 23 g. 5. 7.31 × 10 ... 40.0 grams of S will react leaving 10.0 grams. S unreacted. 013. 10.0 points ... FeCl2 and K2CO3 is ... 9. 1. There is no reaction. 2. KCl electrolyte. 3. CO2 gas. 4. FeCO3 precipitate. correct.
Explanation:
<span>nuclear symbol consists of three parts: 1. the symbol of the
element; 2. the atomic number of the element;3. the mass of the element. for
the above problem, the symbol for potassium is k. it's atomic number is 40. the
number of protons is 19. so we denote this in the following nuclear symbol; 40
k 19</span>
