Question

nickel carbonyl decomposes to form nickel and carbon monoxide, like this:
ni(co)₄(g)→ni(s)+4co(g)
at a certain temperature, a chemist finds that a 2.3 l reaction vessel containing a mixture of nickel carbonyl, nickel, and carbon monoxide at equilibrium has the following composition:

calculate the value of the equilibrium constant kₑ for this reaction. round your answer to 2 significant digits.

kₑ =

Explanation:

Step1: Calculate molar concentrations

• Molar mass of \(Ni(CO)_4\): \(M_{Ni(CO)_4}=170.73\space g/mol\). Concentration \(c_{Ni(CO)_4}=\frac{n}{V}=\frac{\frac{0.789\space g}{170.73\space g/mol}}{2.3\space L}\approx2.03\times10^{-3}\space mol/L\)
• Molar mass of \(CO\): \(M_{CO} = 28.01\space g/mol\). Concentration \(c_{CO}=\frac{n}{V}=\frac{\frac{1.62\space g}{28.01\space g/mol}}{2.3\space L}\approx0.0253\space mol/L\)
• \(Ni\) is a solid, its concentration is not included in \(K_c\) expression.

Step2: Write \(K_c\) expression

For \(Ni(CO)_4(g)
ightleftharpoons Ni(s)+4CO(g)\), \(K_c=\frac{[CO]^4}{[Ni(CO)_4]}\)

Step3: Substitute values

\(K_c=\frac{(0.0253)^4}{2.03\times 10^{-3}}\)
\((0.0253)^4=4.09\times10^{-6}\)
\(K_c=\frac{4.09\times 10^{-6}}{2.03\times 10^{-3}}\approx0.0020\)

Answer:

\(0.0020\)