Books(current) Courses (current) Earn 💰 Log in(current)

Problem 108

Consider the formation of ammonia: $$\mathrm{N}_…

View
Problem 111

Synthesis gas, a mixture that includes the fuels CO and $\mathrm{H}_{2}$, is used to produce liquid hydrocarbons and methanol. It is made at pressures up to 100 atm by oxidation of methane followed by the steam reforming and water-gas shift reactions. Because the process is exothermic, temperatures reach $950-1100^{\circ} \mathrm{C}$, and the conditions are such that the amounts of $\mathrm{H}_{2}, \mathrm{CO}, \mathrm{CO}_{2}, \mathrm{CH}_{4}$, and $\mathrm{H}_{2} \mathrm{O}$ leaving the reactor are close to the equilibrium amounts for the steam re-forming and water-gas shift reactions:
$$\begin{aligned} \mathrm{CH}_{4}(g)+\mathrm{H}_{2} \mathrm{O}(g) & \rightleftharpoons \mathrm{CO}(g)+3 \mathrm{H}_{2}(g) \quad \text { (steam re-forming) } \\ \mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(g) & \rightleftharpoons \mathrm{CO}_{2}(g)+\mathrm{H}_{2}(g) \quad \text { (water-gas shift) } \end{aligned}$$
(a) At $1000 .$ ', what are $\Delta G^{\circ}$ and $\Delta H^{\circ}$ for the steam re-forming
reaction and for the water-gas shift reaction?
(b) By doubling the steam re-forming step and adding it to the water-gas shift step, we obtain the following combined reaction:
$$2 \mathrm{CH}_{4}(g)+3 \mathrm{H}_{2} \mathrm{O}(g) \rightleftharpoons \mathrm{CO}_{2}(g)+\mathrm{CO}(g)+7 \mathrm{H}_{2}(g)$$
Is this reaction spontaneous at $1000 .^{\circ} \mathrm{C}$ in the standard state?
(c) Is it spontaneous at 98 atm and $50 . \%$ conversion (when $50 . \%$ of the starting materials have reacted)?
(d) Is it spontaneous at 98 atm and $90 . \%$ conversion?

University of New Mexico

This question is in the process of being solved. The video shown is an answer to a question that covers similar topics.

Problem 107

In the process of respiration, glucose is oxidized completely. In fermentation, $\mathrm{O}_{2}$ is absent and glucose is broken down to ethanol and $\mathrm{CO}_{2}$ . Ethanol is oxidized to $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ .
(a) Balance the following equations for these processes:
Respiration: $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(s)+\mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l)$
Fermentation: $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(s) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(l)+\mathrm{CO}_{2}(g)$
Ethanol oxidation: $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(l)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l)$
(b) Calculate $\Delta G_{\mathrm{rxn}}^{\circ}$ for respiration of 1.00 $\mathrm{g}$ of glucose.
(c) Calculate $\Delta G_{\mathrm{rxn}}^{\circ}$ for fermentation of 1.00 $\mathrm{g}$ of glucose.
(d) Calculate $\Delta G_{\mathrm{rxn}}^{\circ}$ for oxidation of the ethanol from part (c).

Answer
Check back soon!
Chapter 20
Thermodynamics: Entropy, Free Energy, and the Direction of Chemical Reactions
CHEMISTRY: The Molecular Nature of Matter and Change 2016

Topics


Discussion

You must be signed in to discuss.

Video Transcript

No transcript available

Recommended Questions