To determine the correct formula equation for the reaction between fluorine gas and calcium metal that produces calcium fluoride powder, let's break down the problem step-by-step and examine each option given.
1. Reactants and Products:
- Reactants: Fluorine gas (F₂) and calcium metal (Ca).
- Product: Calcium fluoride (CaF₂) in powder form, which is solid.
2. Chemical States:
- Fluorine gas (F₂) is in the gaseous state, so it should be denoted as [tex]\( F_2(g) \)[/tex].
- Calcium metal (Ca) is in the solid state, denoted as [tex]\( Ca(s) \)[/tex].
- Calcium fluoride (CaF₂) forms as a solid, since powders are typically solid substances. Therefore, it should be denoted as [tex]\( CaF_2(s) \)[/tex].
3. Equation Format:
- The reactants and products need to be written correctly, and a triangle symbol (△) should indicate that the reaction takes place under high temperatures.
Given this information, let's examine each provided option:
1. Option 1:
[tex]\[ F_2(l) + Na(s) \longrightarrow NaF_2(s) \][/tex]
- This equation incorrectly uses sodium (Na) instead of calcium (Ca).
- Fluorine is incorrectly stated as a liquid (l) instead of a gas (g).
- The product NaF₂ is not relevant to the given problem.
2. Option 2:
[tex]\[ F_2(g) + Ca(s) \longrightarrow CaF_2(l) \][/tex]
- This equation correctly uses fluorine gas (F₂(g)) and calcium metal (Ca(s)).
- However, it incorrectly states that the product calcium fluoride (CaF₂) is a liquid (l) instead of the correct solid (s).
3. Option 3:
[tex]\[ F_2(g) + Na(s) \xrightarrow{\triangle} NaF_2(l) \][/tex]
- This equation incorrectly uses sodium (Na) instead of calcium (Ca).
- The product NaF₂ is expected to be a liquid, which is incorrect.
4. Option 4:
[tex]\[ F_2(g) + Ca(s) \xrightarrow{\triangle} CaF_2(s) \][/tex]
- This correctly uses fluorine gas (F₂(g)) and calcium metal (Ca(s)).
- The product calcium fluoride (CaF₂) is correctly noted as a solid (s).
- The reaction indicates it occurs under high temperatures (△).
Therefore, the correct formula equation for the reaction of fluorine gas with calcium metal to produce calcium fluoride powder is:
[tex]\[ F_2(g) + Ca(s) \xrightarrow{\triangle} CaF_2(s) \][/tex]
This matches Option 4.
