Question #2d5bf

1 Answer
Sep 1, 2017

Answer:

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?