Skip to content
MathsGenie logo
Open app

Course home

  1. A Level
  3. Chemistry OCR A
  5. Question bank

Redox and electrode potentials

EasyMedium
12345678910111213141516171819
Question 14

The redox equilibria for a direct methanol fuel cell under standard acidic conditions are shown below.

CO2(g)+6H+(aq)+6e−⇌CH3OH(aq)+H2O(l)Eθ=+0.02 V \text{CO}_2(\text{g}) + 6\text{H}^+(\text{aq}) + 6\text{e}^- \rightleftharpoons \text{CH}_3\text{OH}(\text{aq}) + \text{H}_2\text{O}(\text{l}) \quad E^\theta = +0.02\text{ V} CO2​(g)+6H+(aq)+6e−⇌CH3​OH(aq)+H2​O(l)Eθ=+0.02 V O2(g)+4H+(aq)+4e−⇌2H2O(l)Eθ=+1.23 V \text{O}_2(\text{g}) + 4\text{H}^+(\text{aq}) + 4\text{e}^- \rightleftharpoons 2\text{H}_2\text{O}(\text{l}) \quad E^\theta = +1.23\text{ V} O2​(g)+4H+(aq)+4e−⇌2H2​O(l)Eθ=+1.23 V

What is the equation for the overall cell reaction when the cell is discharging?

2CH3OH(aq)+3O2(g)→2CO2(g)+4H2O(l) 2\text{CH}_3\text{OH}(\text{aq}) + 3\text{O}_2(\text{g}) \rightarrow 2\text{CO}_2(\text{g}) + 4\text{H}_2\text{O}(\text{l}) 2CH3​OH(aq)+3O2​(g)→2CO2​(g)+4H2​O(l)
2CO2(g)+4H2O(l)→2CH3OH(aq)+3O2(g) 2\text{CO}_2(\text{g}) + 4\text{H}_2\text{O}(\text{l}) \rightarrow 2\text{CH}_3\text{OH}(\text{aq}) + 3\text{O}_2(\text{g}) 2CO2​(g)+4H2​O(l)→2CH3​OH(aq)+3O2​(g)
2CH3OH(aq)+2H2O(l)+3O2(g)→2CO2(g)+6H2O(l) 2\text{CH}_3\text{OH}(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) + 3\text{O}_2(\text{g}) \rightarrow 2\text{CO}_2(\text{g}) + 6\text{H}_2\text{O}(\text{l}) 2CH3​OH(aq)+2H2​O(l)+3O2​(g)→2CO2​(g)+6H2​O(l)
CH3OH(aq)+O2(g)→CO2(g)+2H2O(l) \text{CH}_3\text{OH}(\text{aq}) + \text{O}_2(\text{g}) \rightarrow \text{CO}_2(\text{g}) + 2\text{H}_2\text{O}(\text{l}) CH3​OH(aq)+O2​(g)→CO2​(g)+2H2​O(l)

Redox and electrode potentials Questions

  1. A Level
  2. /Chemistry
  3. /Redox and electrode potentials