MDCAT Electrochemistry MCQs

Sample Electrochemistry MCQs with answers

Try these questions, then open the answer to check your reasoning. Use the quiz above for more topics and a complete review.

1. Redox Reactions

   1. Redox reactions actually transfer:

   1. A. Electrons
   2. B. Charges
   3. C. Energy
   4. D. Hydrogen ions
   View answer and explanation

   Answer: A. Electrons

   Oxidation is loss of electrons and reduction is gain of electrons, so every redox process fundamentally involves electron transfer between species. Charge, energy and hydrogen ions may accompany the change but are not the transferred entity. Hence redox reactions transfer electrons.

2. SHE

   2. A cell has E° $cathode=+0.54$ V and E° $cell=+1.30$ V. What is E°anode as a reduction potential?

   1. A. + $1.84\mathrm{V}$
   2. B. − $0.76\mathrm{V}$
   3. C. + $0.76\mathrm{V}$
   4. D. − $1.84\mathrm{V}$
   View answer and explanation

   Answer: B. − $0.76\mathrm{V}$

   Using E° $cell=E^{\circ }cathode$ − E°anode gives 1. $30=0.54$ − E°anode, so E° $anode=-0.76$ V.

3. SHE

   3. The standard electrode potential is the potential of an electrode which is set up when:

   1. A. It is immerse in 0.1 M solution of other ions at $298\mathrm{K}$
   2. B. It is immerse in 1 M solution of its own ions at $298\mathrm{K}$
   3. C. It is brought in contact with other electrode at any temperature
   4. D. It is immerse in IM solution of any concentration acid at $298\mathrm{K}$
   View answer and explanation

   Answer: B. It is immerse in 1 M solution of its own ions at $298\mathrm{K}$

   Keyword/Clue: standard electrode potential and 1 M at $298\mathrm{K}$ Concept/Formula: textbf{Standard electrode potential (E∘)} is the electrode potential measured under standard conditions: solute activity ≈ 1 M for the electrode’s own ions (or 1 bar for gases) at $298\mathrm{K}$, typically relative to SHE. Why the Other Options Are Wrong: - Option A: Uses 0.1 M and “other ions”; not standard conditions and not necessarily the electrode’s own ion. - Option C: Standard potential is not defined by contacting another electrode at any temperature; temperature must be standard ($298\mathrm{K}$). - Option D: “1 M acid of any concentration” is self-contradictory and not the definition; it must be 1 M of its own ions, not arbitrary acid.