1.The oxidation number of platinum in Pt(H2O)4 ^+2 is *
a. +4
b. +1/2
c. 0
d. +2
2.When a fuel undergoes complete combustion, it releases the _____ amount of energy from the fuel being reacted. *
a. just enough
b. acceptable
c. maximum
d. minimum
The Correct Answer and Explanation is :
- The oxidation number of platinum in Pt(H₂O)₄²⁺ is +2.
Explanation:
To determine the oxidation number of platinum (Pt) in the complex ion Pt(H₂O)₄²⁺, let’s break down the calculation:
- Water (H₂O) is a neutral molecule, so each water molecule does not contribute to the overall charge.
- The complex ion, Pt(H₂O)₄²⁺, has a total charge of +2. Since the water molecules are neutral, the charge of the platinum ion must balance the +2 charge of the entire complex.
- Therefore, the oxidation number of platinum (Pt) is +2.
- When a fuel undergoes complete combustion, it releases the maximum amount of energy from the fuel being reacted.
Explanation:
In a combustion reaction, a fuel (such as hydrocarbons or other organic compounds) reacts with oxygen, producing carbon dioxide (CO₂) and water (H₂O) as products. Combustion is typically categorized as either complete or incomplete.
- Complete combustion occurs when there is enough oxygen to fully oxidize the fuel, resulting in the production of carbon dioxide and water. This reaction releases the maximum amount of energy possible for the particular fuel. Complete combustion is highly efficient in terms of energy release because it ensures the full conversion of the fuel into its oxidized forms (CO₂ and H₂O). For example, when methane (CH₄) undergoes complete combustion, it reacts with oxygen to produce carbon dioxide and water, releasing a significant amount of energy: CH₄ + 2O₂ → CO₂ + 2H₂O + energy
- Incomplete combustion, on the other hand, happens when there is insufficient oxygen, leading to the formation of carbon monoxide (CO) or even elemental carbon (soot), which results in the release of less energy.
Thus, complete combustion releases the maximum amount of energy possible from the fuel because all of the fuel’s chemical energy is efficiently converted into usable energy in the form of heat and light.