Use the following data to estimate a value of \(K_{\mathrm{p}}\) at \(1200 \mathrm{K}\) for the reaction \(2 \mathrm{H}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightleftharpoons 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})\) $$\begin{array}{l} \text { C(graphite) }+\mathrm{CO}_{2}(\mathrm{g}) \rightleftharpoons 2 \mathrm{CO}(\mathrm{g}) \quad K_{\mathrm{c}}=0.64 \\ \quad \mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2}(\mathrm{g}) \rightleftharpoons \mathrm{CO}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \quad K_{\mathrm{c}}=1.4 \\ \text { C(graphite) }+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g}) \rightleftharpoons \mathrm{CO}(\mathrm{g}) \quad K_{\mathrm{c}}=1 \times 10^{8} \end{array}$$

Short Answer

Expert verified
The value of \(K_p\), the equilibrium constant for the reaction \(2H_2(g) + O_2(g) \rightleftharpoons 2H_2O(g)\) at 1200 K is \( (1//64) * 1.4 * (1 × 10^8)^2 \).

Step by step solution

01

Identifying the Needed Reactions

Inspect given reactions and identify which ones can be manipulated algebraically (through reverse, multiply or addition/subtraction) to obtain the desired reaction \(2H_2(g) + O_2(g) \rightleftharpoons 2H_2O(g)\). The ones to be used are: \n \n C(graphite) + CO2(g) \rightleftharpoons 2CO(g) with \(K_c=0.64\); \n CO2(g) + H2(g) \rightleftharpoons CO(g) + H2O(g) with \(K_c=1.4\); \n C(graphite) + 0.5O2(g) \rightleftharpoons CO(g) with \(K_c=1 × 10^8\)
02

Manipulate the Reactions and the Corresponding Equilibrium Constants

In order to add the reactions to achieve the desired final reaction, reverse the first reaction:2CO(g) \rightleftharpoons C(graphite) + CO2(g) with \(K_c= 1/0.64\),keep the second reaction as is and multiply the third reaction by 2:2C(graphite) + O2(g) \rightleftharpoons 2CO(g) with \(K_c= (1 × 10^8)^2\). Since reversing a reaction inverts the equilibrium constant and changing the coefficient of the reaction elevates the \(K_c\) to that power.
03

Adding up Reactions and Corresponding Equilibrium Constants

Add up the reactions manipulated in step one:\[ 2CO(g) \rightleftharpoons C(graphite) + CO2(g) \]\[ CO2(g) + H2(g) \rightleftharpoons CO(g) + H2O(g) \]\[ 2C(graphite) + O2(g) \rightleftharpoons 2CO(g)\]This results in the desired final reaction: \[ 2H_2(g) + O2(g) \rightleftharpoons 2H_2O(g)\]In the same manner, add up the corresponding \(K_c\)s by multiplying them together, as when adding up reactions, the corresponding equilibrium constants multiply. Therefore, the final \(K_c\) for the desired reactions is: \( (1/0.64) * 1.4 * (1 × 10^8)^2 \).
04

Conversion from \(K_c\) to \(K_p\)

Since the question asks for the value of \(K_p\) and the resultant equilibrium constant achieved is \(K_c\), transform \(K_c\) to \(K_p\) using the formula \(K_p = K_c (RT)^{\Delta n}\) where \(R\) is the ideal gas constant (0.08314 L bar /mol K), \(T\) is the absolute temperature in Kelvin (1200 K in this case), and \(\Delta n\) is the change in stoichiometric number (sum of the stoichiometric coefficient of the gaseous products minus the sum of the stoichiometric coefficient of the gaseous reactants). Substituting the obtained \(K_c\) and given \(T\) value and with the \(\Delta n\) being 0 in this given reaction because the number of gaseous moles remains the same on both sides of the reaction, solve for \(K_p\).
05

Calculate \(K_p\)

As \(\Delta n\) is zero, the equation simplifies to \(K_p = K_c\). The final \(K_p\) will be \( (1//64) * 1.4 * (1 × 10^8)^2 \), after doing the math.

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Most popular questions from this chapter

For the dissociation reaction \(2 \mathrm{H}_{2} \mathrm{S}(\mathrm{g}) \rightleftharpoons 2 \mathrm{H}_{2}(\mathrm{g})+\) \(\mathrm{S}_{2}(\mathrm{g}), K_{\mathrm{p}}=1.2 \times 10^{-2}\) at \(1065^{\circ} \mathrm{C} .\) For this same reaction at \(1000 \mathrm{K},\) (a) \(K_{\mathrm{c}}\) is less than \(K_{\mathrm{p}} ;\) (b) \(K_{\mathrm{c}}\) is greater than \(K_{\mathrm{p}} ;(\mathrm{c}) K_{\mathrm{c}}=K_{\mathrm{p}} ;\) (d) whether \(K_{\mathrm{c}}\) is less than, equal to, or greater than \(K_{\mathrm{p}}\) depends on the total gas pressure.

In the reversible reaction \(\mathrm{H}_{2}(\mathrm{g})+\mathrm{I}_{2}(\mathrm{g}) \rightleftharpoons\) \(2 \mathrm{HI}(\mathrm{g}),\) an initial mixture contains \(2 \mathrm{mol} \mathrm{H}_{2}\) and 1 mol I \(_{2} .\) The amount of HI expected at equilibrium is (a) \(1 \mathrm{mol} ;\) (b) \(2 \mathrm{mol} ;\) (c) less than \(2 \mathrm{mol}\); (d) more than 2 mol but less than 4 mol.

A sample of \(\mathrm{NH}_{4} \mathrm{HS}(\mathrm{s})\) is placed in a \(2.58 \mathrm{L}\) flask containing 0.100 mol \(\mathrm{NH}_{3}(\mathrm{g}) .\) What will be the total gas pressure when equilibrium is established at \(25^{\circ} \mathrm{C} ?\) $$\begin{aligned} \mathrm{NH}_{4} \mathrm{HS}(\mathrm{s}) \rightleftharpoons \mathrm{NH}_{3}(\mathrm{g})+\mathrm{H}_{2} \mathrm{S}(\mathrm{g}) & \\ K_{\mathrm{p}} &=0.108 \text { at } 25^{\circ} \mathrm{C} \end{aligned}$$

Explain how each of the following affects the amount of \(\mathrm{H}_{2}\) present in an equilibrium mixture in the reaction \(3 \mathrm{Fe}(\mathrm{s})+4 \mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{Fe}_{3} \mathrm{O}_{4}(\mathrm{s})+4 \mathrm{H}_{2}(\mathrm{g})\) $$ \Delta H^{\circ}=-150 \mathrm{kJ} $$ (a) Raising the temperature of the mixture; (b) introducing more \(\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) ;\) (c) doubling the volume of the container holding the mixture; (d) adding an appropriate catalyst.

The reaction \(\mathrm{N}_{2}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g}), \quad \Delta H^{\circ}=\) \(+181 \mathrm{kJ},\) occurs in high-temperature combustion processes carried out in air. Oxides of nitrogen produced from the nitrogen and oxygen in air are intimately involved in the production of photochemical smog. What effect does increasing the temperature have on (a) the equilibrium production of \(\mathrm{NO}(\mathrm{g})\) (b) the rate of this reaction?

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