The correct answer is D:
it involves breaking molecular bonds between copper compounds .
The explanation :
-when we melt a copper it is a physical change because the substance is still copper and have the same shape.
- but for example Burning a copper it is a chemical change. Fire activates a chemical reaction between copper and oxygen.
-The oxygen in the air reacts with the copper and the chemical bonds are broken.
- the chemical change is changing the other compound bonded to the copper atoms.
So, the correct answer is D
½N2(g) + O2(g) + 8.1 kcal → NO2(g)
½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal
C(diamond) + O2(g) → CO2, ΔH = -94.50 kcal
Answer:
2) ½N2(g) + O2(g) + 8.1 kcal → NO2(g)
Explanation:
Chemical reactions in general can be classified as endothermic and exothermic reactions.
Endothermic reactions are accompanied by the absorption of energy. Here, the enthalpy (ΔH) change of the reaction is positive.
Exothermic reactions are accompanied by the release of energy. Here, the enthalpy (ΔH) change of the reaction is negative.
1)H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal
Here, ΔH is negative, hence exothermic
2)½N2(g) + O2(g) + 8.1 kcal → NO2(g)
Here, energy is being absorbed, hence endothermic
3) ½N2(g) + 3/2H2(g) → NH3(g) + 11.0 kcal
Here, energy is released, hence exothermic
4)C(diamond) + O2(g) → CO2, ΔH = -94.50 kcal
Here, ΔH is negative, hence exothermic
The exothermic step in ozone reactions is O₃ → O₂ + O. The most endothermic step is 3O₂ → 2O₃ because it needs energy to break the double bond in O₂. Ozone can be decomposed by light with a longer wavelength because the O-O bond in ozone is weaker than the O=O double bond in oxygen.
The reactions mentioned are involved in the ozone production and destruction in the atmosphere. The first reaction : 3O₂ → 2O₃ is an endothermic process as it needs energy (in the form of UV light) to break the double bond in O₂ and form O₃. However, the reaction : O₃ → O₂ + O is exothermic. It involves the breaking of the weaker bond in O3 and formation of a stronger O₂ molecule and oxygen atom. Thus, the answer to part (a) would be the step O₃ → O₂ + O.
For part (b), the most endothermic step would again be 3O₂ → 2O₃. Lastly, the explanation of why ozone can be decomposed by light with a longer wavelength than that required to decompose oxygen is because the O-O bond in ozone is weaker than the O=O double bond in oxygen. Hence, it requires less energy (or light of longer wavelength) to break the O-O bond in ozone, leading to its decomposition.
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#SPJ1
B. a nonmetal and a metal.
C. an acid and oxygen.
D. a base and an acid.
A salt is obtained as a reaction between a base and an acid which is option D.
A salt is obtained as a reaction between a base and an acid. In this reaction, the base donates a hydroxide ion (OH⁻) and the acid donates a hydrogen ion (H⁺). The hydroxide ion and hydrogen ion combine to form water (H₂O), and the remaining ions from the base and acid combine to form the salt. The salt is typically composed of a metal cation from the base and a non-metal anion from the acid. The formation of salt is a neutralization reaction where the acidic and basic properties of the reactants are neutralized, resulting in the formation of a new compound, the salt.
Hence, the correct option is option d.
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#SPJ 6
The molecules will move faster
Answer:
Decrease order of speed of atoms in solid state, liquid state and gaseous states: gas > liquid> solid
Decreasing order of space of atoms in solid state, liquid state and gaseous states: gas > liquid> solid
Explanation:
Solid state : In this state, the particles are closely packed and does not have any space between them. They have least kinetic energy due to restricted movement. This state has a definite shape and volume.
Liquid state : In this state, particles are present in random and irregular pattern. The particles are closely arranged but they can move from one place to another and thus have higher kinetic energy as compared to solids. This state has a definite volume but does not have a fixed shape.
Gaseous state : In this state, particles are loosely arranged and have a lot of space between them. They have highest kinetic energy. This state has indefinite volume as well as shape.
Decrease order of speed of atoms in solid state, liquid state and gaseous states: gas > liquid> solid
Decreasing order of space of atoms in solid state, liquid state and gaseous states: gas > liquid> solid