Answer: The standard enthalpy of formation of 
is -252.1 kJ/mol.
Explanation:
The balanced chemical reaction is,
The expression for enthalpy change is,
![\Delta H=[n\times H_f_{products}]-[n\times H_f_{reactantss}]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Bn%5Ctimes%20H_f_%7Bproducts%7D%5D-%5Bn%5Ctimes%20H_f_%7Breactantss%7D%5D)
Putting the values we get :
![\Delta H=[2\times H_f{Fe}+3\times H_f{H_2O}]-[1\times H_f{Fe_2O_3}+3\times H_f{H_2}]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B2%5Ctimes%20H_f%7BFe%7D%2B3%5Ctimes%20H_f%7BH_2O%7D%5D-%5B1%5Ctimes%20H_f%7BFe_2O_3%7D%2B3%5Ctimes%20H_f%7BH_2%7D%5D)
![67.9kJ=[(2\times 0)+(3\times H_f{H_2O})]-[(1\times -824.2kJ/mol)+3\times 0kJ/mol)]](https://tex.z-dn.net/?f=67.9kJ%3D%5B%282%5Ctimes%200%29%2B%283%5Ctimes%20H_f%7BH_2O%7D%29%5D-%5B%281%5Ctimes%20-824.2kJ%2Fmol%29%2B3%5Ctimes%200kJ%2Fmol%29%5D)
Thus standard enthalpy of formation of is -252.1 kJ/mol.
Decomposition,because 1 breaks down into 2
Charcoal with a carbon-14 activity of 0.60 compared to new wood has less than 5,730 years.
<h3>What is a radioactive isotope?</h3>
A radioactive isotope is an element in nature that emit radioactivity in a given period of time (e.g., the half-life for C14 is equal to 5,730 years).
Radioactive dating is a technique to measure the age of an element by measuring its radioactive activity.
In conclusion, charcoal with a carbon-14 activity of 0.60 compared to new wood has less than 5,730 yr.
Learn more about radioactive dating here:
brainly.com/question/8831242
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Answer:
Explanation:
The oxidation number is an integer that represents the number of electrons that an atom receives or makes available to others when it forms a given compound.
The oxidation number is positive if the atom loses electrons, or shares them with an atom that has a tendency to accept them. And it will be negative when the atom gains electrons, or shares them with an atom that has a tendency to give them up.
Chemical compounds are electrically neutral. That is, the charge that all the atoms of a compound contribute must be globally null. That is, when having positive or negative charges in a compound, their sum must be zero.
There are some rules for determining oxidation numbers in compounds. Among them it is possible to mention:
- Hydrogen (H) has an oxidation number +1 with nonmetals and - 1 with metals.
- Oxygen (O) presents the oxidation number -2
- Fluorine F has a unique oxidation state -1
Then:
- NOF: N+(-2)+(-1)=0 → N=3 → oxidation number of nitrogen (N) is +3, oxidation number of oxygen (O) is -2 and oxidation number of fluorine (F) is -1.
- ClF₅: Cl + 5*(-1)=0 → Cl= 5 → oxidation number of chlorine (Cl) is +5 and oxidation number of fluorine (F) is -1.
- H₂SO₃: 2*(+1)+S+3*(-2)=0 → S=4 → oxidation number of hydrogen (H) is +1, oxidation number of oxygen (O) is -2 and oxidation number of sulfur (S) is +4.
