Consider the following reaction: Pyruvate + NADH + H+ ⟶ Lactate + NAD+ The half-cell reactions (with their standard reduction potentials) are: Pyruvate + 2H+ + 2e- ⟶ Lactate (-0.19V) NAD+ + H+ + 2e- ⟶ NADH (-0.32V) What is the reduction potential for the overall reaction? Group of answer choices: a. Cannot determine from the information provided b. -0.13 V c. +0.13 V d. +0.51 V e. -0.51 V Based on your ΔE°' answer, please calculate the corresponding ΔG°' value. Is the reaction spontaneous? In your answer, you must show the equation used (use tools above) and show all work, including units on your answer.
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19 V and E°anode = -0.32 V E°cell = -0.19 - (-0.32) E°cell = -0.19 + 0.32 E°cell = 0.13 V Show more…
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The half-reactions involved in the lactate dehydrogenase (LDH) reaction and their standard reduction potentials are \[\begin{array}{ll}\text { Pyruvate }+2 \mathrm{H}^{+}+2 e^{-} \longrightarrow \text { lactate } & \mathscr{E}^{\circ}=-0.185 \mathrm{V} \\ \mathrm{NAD}^{+}+2 \mathrm{H}^{+}+2 e^{-} \longrightarrow \mathrm{NADH}+\mathrm{H}^{+} & \mathscr{E}^{\circ \prime}=-0.315 \mathrm{V}\end{array}\]Calculate $\Delta G$ at $\mathrm{pH} 7.0$ for the LDH-catalyzed reduction of pyruvate under the following conditions: (c) [lactate]/[pyruvate] $=1000$ and $\left[\mathrm{NAD}^{+}\right] /[\mathrm{NADH}]=1000$ (d) Discuss the effect of the concentration ratios in Parts a-c on the direction of the reaction. (a) [lactate]/[pyruvate] $=1$ and $\left[\mathrm{NAD}^{+}\right] /[\mathrm{NADH}]=1$ (b) [lactate]/[pyruvate] $=160$ and $\left[\mathrm{NAD}^{+}\right] /[\mathrm{NADH}]=160$
The half-reactions involved in the lactate dehydrogenase (LDH) reaction and their standard reduction potentials are $$\begin{array}{l}\text { Pyruvate }+2 \mathrm{H}^{-}+2 r^{-} \longrightarrow \text { luctate } \quad \varepsilon^{0}=-0.185 \mathrm{V} \\\mathrm{NAD}^{\prime}+2 \mathrm{H}^{2}+2 \mathrm{c}^{2} \longrightarrow \mathrm{NADH}+\mathrm{H}^{+} \quad 8^{-1}--0.315 \mathrm{V}\end{array}$$ Calculate $\Delta G$ as $p H$ 7.0 for the LDH-catalyzed reduction of pyruvate under the following conditions: (a) [lactate]/[pyruvate] $=1$ and $\left[\mathrm{NAD}^{+}\right] /[\mathrm{NADH}]=1$ (b) $|$ lactate $|$ pynuvate $= 160$ and $\left|\mathrm{NAD}^{*}\right| /(\mathrm{NAD} \mathrm{H})=160$ (c) $|$ lactare $|$ / pynuvate $|= 1000$ and $\left|\mathrm{NAD}^{*}\right| /|\mathrm{NADH}|=1000$ (d) Discuss the effect of the concentration ration in parts a-c on the direction of the reaction.
Glucose Metabolism The standard potentials for the reduction of nicotinamide adenine dinucleotide (NAD') and oxaloacetate (reactants in the multistep metabolism of glucose) are as follows: $\mathrm{NAD}^{+}(a q)+2 \mathrm{H}^{+}(a q)+2 \mathrm{e}^{-} \rightarrow \mathrm{NADH}(a q)+\mathrm{H}^{+}(a q)$ $$ E^{*}=-0.320 \mathrm{V} $$ Oxaloacetate $^{2-}(a q)+2 \mathrm{H}^{+}(a q)+2 \mathrm{e}^{-} \rightarrow$ malate $^{2-}(a q)$ $$ E^{\circ}=-0.166 \mathrm{V} $$ a. Calculate the standard potential for the following reaction: Oxaloacetate $^{2-}(a q)+\mathrm{NADH}(a q)+\mathrm{H}^{+}(a q) \rightarrow$ $$ \text { malate }^{-}(a q)+\mathrm{NAD}^{+}(a q) $$ b. Calculate the equilibrium constant for the reaction at $25^{\circ} \mathrm{C}$
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