The given question is incomplete. The complete question is
The thermite reaction, in which powdered aluminum reacts with iron oxide, is highly exothermic: 
. Use standard enthalpies of formation to find ΔH∘rxn for the thermite reaction. Express the heat of the reaction in kilojoules to four significant figures.
Answer: ΔH∘rxn for the thermite reaction is -851.5 kJ
Explanation:
The balanced chemical reaction is :
We have to calculate the enthalpy of reaction 
.
![\Delta H^o=[n_{Fe}\times \Delta H_f^0_{(Fe)}+n_{Al_2O_3}\times \Delta H_f^0_{(Al_2O_3)}]-[n_{Al}\times \Delta H_f^0_(Al)+n_{Fe_2O_3}\times \Delta H_f^0_{(Fe_2O_3)}]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo%3D%5Bn_%7BFe%7D%5Ctimes%20%5CDelta%20H_f%5E0_%7B%28Fe%29%7D%2Bn_%7BAl_2O_3%7D%5Ctimes%20%5CDelta%20H_f%5E0_%7B%28Al_2O_3%29%7D%5D-%5Bn_%7BAl%7D%5Ctimes%20%5CDelta%20H_f%5E0_%28Al%29%2Bn_%7BFe_2O_3%7D%5Ctimes%20%5CDelta%20H_f%5E0_%7B%28Fe_2O_3%29%7D%5D)
where,
We are given:
Putting values in above equation, we get:
![\Delta H^o_{rxn}=[(2\times 0)+(1\times -1675.5)]-[(2\times 0)+(1\times -824.2)]=-851.5kJ](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B%282%5Ctimes%200%29%2B%281%5Ctimes%20-1675.5%29%5D-%5B%282%5Ctimes%200%29%2B%281%5Ctimes%20-824.2%29%5D%3D-851.5kJ)
ΔH∘rxn for the thermite reaction is -851.5 kJ
67g KCl(1 mol KCl/74.55g)=0.8987256875 mol KCl
0.8987256875 mol KCl(6.02*10^23 molecules/ 1 mol)
=5.410328638*10^23 molecules KCl
An element is a species of atom that has the same amounts of electrons and protons in their nuclei. To know which of these substances are elements, we can look it up in the periodic table of elements. The elements are as follows:
1.silicon
2.lead
3.silicone
5.iodine
12 HClO₄ + 1 P₄O₁₀ → 4 H₃PO₄ + 6 Cl₂O₇
<h3>Explanation</h3>
Balance by the conservation of atoms.
Assign coefficient <em>1 </em>to the species with the largest number of elements and atoms. H₃PO₄ contains three elements. Each of its molecule contains eight atoms, that's two more than the six atoms in a HClO₄ molecule. Start by assigning H₃PO₄ a coefficient of <em>1</em>.
? HClO₄ + ? P₄O₁₀ → <em>1</em> H₃PO₄ + ? Cl₂O₇
There are now three H atoms, one P atom on the product side. H₃PO₄ is the only product that contains H and P atoms. As a result, there should be the same number of H and P atoms on the reactant side.
- Among all reactants, only HClO₄ contains H atoms. Each HClO₄ molecule contains one H atom. Three H atoms correspond to three HClO₄ molecule.
- Among all reactants, only P₄O₁₀ contains P atoms. Each P₄O₁₀ molecule contains four P atoms. One P atom corresponds to 1/4 of a P₄O₁₀ molecule.
Thus
<em>3</em> HClO₄ + <em>1/4</em> P₄O₁₀ → <em>1</em> H₃PO₄ + ? Cl₂O₇
There are three Cl atoms in three HClO₄ molecules. HClO₄ is the only species that contains Cl among all reactants. There are three Cl atoms on the reactant side and shall be the same number of Cl atoms on the product side.
- Cl₂O₇ is the only molecule that contains Cl among the products. Each Cl₂O₇ molecule contains two Cl atoms. Three Cl atoms will correspond to 3/2 Cl₂O₇ molecules.
<em>3</em> HClO₄ + <em>1/4</em> P₄O₁₀ → <em>1</em> H₃PO₄ + <em>3/2</em> Cl₂O₇
Multiply both sides by the least common multiple of the denominators to eliminate the fraction. The least common multiple in this case is four.
12 HClO₄ + 1 P₄O₁₀ → 4 H₃PO₄ + 6 Cl₂O₇
Answer: Biodiversity is important to humans for many reasons. ... Ecological life support— biodiversity provides functioning ecosystems that supply oxygen, clean air and water, pollination of plants, pest control, wastewater treatment and many ecosystem services.
Explanation:
