Question

which of the following represents a formation equation for c₆h₅oh(l)?
○ 6 c(g) + 3 h₂(g) + 1/2 o₂(g) → c₆h₅oh(l)
○ c₆h₅oh(l) → 6 c(g) + 3 h₂(g) + 1/2 o₂(g)
○ 6 c(g) + 6 h₂(g) + o₂(g) → c₆h₅oh(l)
○ 6 c(s) + 3 h₂(g) + 1/2 o₂(g) → c₆h₅oh(l)

Explanation:

Step1: Recall Formation Reaction Definition

A formation reaction is when 1 mole of a compound is formed from its elements in their standard states. Standard states: C is solid (s), H₂ is gas (g), O₂ is gas (g), and C₆H₅OH(l) is the compound.

Step2: Analyze Each Option

• Option 1: Reactants are C(g), H₂(g), O₂(g); Products: C₆H₅OH(l). But C's standard state is solid, not gas. Invalid.
• Option 2: Reactant is C₆H₅OH(l), Products are C(g), H₂(g), O₂(g). This is decomposition, not formation. Invalid.
• Option 3: Reactants are C(g), H₂(g), O₂(g); Product: C₆H₅OH(l). C is not in standard state (should be solid). Invalid.
• Option 4: Reactants: 6 C(s) (standard state of C), 3 H₂(g) (standard state of H), ½ O₂(g) (standard state of O). Product: 1 mole of C₆H₅OH(l). This matches formation reaction definition.

Answer:

The fourth option (6 C(s) + 3 H₂(g) + 1/2 O₂(g) → C₆H₅OH(l))