Question

Question #2d5bf

Answer 1

You use the standard molar entropies `S^@` of the reactants and products.

Explanation:

The formula to use is

`color(blue)(barul|stackrel(" ")(Δ_text(rxn)S^@ = sumnS_text(prod)^@ - summS_text(react)^@)|)`

where `m` and `n` are the moles of the reactants and products in the balanced equation.

Here's how to work the first example.

`color(white)(mmmmmmmmm)"C(s)" + "H"_2"O(g)" → "CO(g)" + "H"_2"(g)"`
`S^@"/J·K"^"-1""mol"^"-1": color(white)(m)5.694color(white)(ml)188.72color(white)(mml)197.91color(white)(ml)130.59`

∴ `Δ_text(rxn)S^@ = "(1×197.91 + 1 × 130.59) - (1×5.694 + 1 ×188.72) J/K" = "134.09 J/K"`

The other two reactions use the same method.

Can you get the answers?