Question

question 5
what type of chemical reaction is: 4fe + 3o₂ → 2fe₂o₃?
decomposition
single - displacement
double - displacement
synthesis

question 6
what is usually released in a combustion reaction?
magnetic energy
carbon and hydrogen
oxygen and nitrogen
heat and light

Explanation:

• Question 5:
• Decomposition: A decomposition reaction is when a single compound breaks down into two or more simpler substances. In the given reaction \(4Fe + 3O_{2}\to2Fe_{2}O_{3}\), we are not breaking down a compound but combining elements.
• Single - displacement: A single - displacement reaction has the form \(A+BC\to AC + B\). Here, we have two elements combining, not an element displacing another in a compound.
• Double - displacement: A double - displacement reaction has the form \(AB+CD\to AD+CB\). This reaction does not follow that pattern.
• Synthesis: A synthesis reaction is when two or more substances (in this case, \(Fe\) and \(O_{2}\)) combine to form a single compound (\(Fe_{2}O_{3}\)).
• Question 6:
• Magnetic energy: Combustion reactions are chemical reactions that involve the release of energy in the form of heat and light, not magnetic energy.
• Carbon and hydrogen: In a combustion reaction (e.g., of a hydrocarbon \(C_{x}H_{y}+O_{2}\to CO_{2}+H_{2}O\)), carbon and hydrogen are reactants (in the hydrocarbon) or in the products as parts of carbon - containing and hydrogen - containing compounds, but they are not “released” in the sense of being the main form of energy release.
• Oxygen and nitrogen: Oxygen is often a reactant in combustion (as an oxidizing agent), and nitrogen is usually a spectator (if the combustion is in air). They are not released as the main products in terms of energy.
• Heat and light: Combustion reactions are exothermic (release heat) and often produce light (e.g., burning a candle or a fuel in a stove).

Answer:

• Question 5: synthesis
• Question 6: heat and light