11. electrode potentials and cells

• What is a half cell in an electrochemical cell?

  One half of an electrochemical cell
• What can a half cell be constructed from?

  A metal dipped in its ions or platinum electrode
• What happens when a metal comes into contact with its ions in a half cell?

  A reaction occurs that is in equilibrium
• What is an example of a half cell reaction involving iron?

  Fe2+ + 2 e- ⇌ Fe
• Why is platinum used as an electrode in some half cells?

  It has good electrical conductivity and is inert
• How is an electrochemical cell created?

  By joining two different half cells together
• What components make up an electrochemical cell?

  Two half-cells, a wire, a voltmeter, and a salt bridge
• What does a voltmeter measure in an electrochemical cell?

  The potential difference between two half-cells
• What is the direction of electron flow in an electrochemical cell?

  From a more reactive metal to a less reactive one
• What happens to the zinc electrode in a zinc half cell?

  It gets thinner as zinc converts to ions
• What occurs at the copper electrode in an electrochemical cell?

  Copper ions accept electrons and form copper metal
• What is the role of the salt bridge in an electrochemical cell?

  To complete the circuit and allow ion flow
• What is contained in the salt bridge?

  Saturated potassium nitrate solution
• How is the salt bridge typically constructed?

  Using filter paper dipped in potassium nitrate
• What do electrode potentials measure?

  The tendency of a half cell to give up electrons
• What is the significance of the electrochemical series?

  It shows the electrode potentials of half cells
• How are half equations represented in the electrochemical series?

  In their reduced form with electrons added
• What does a negative electrode potential indicate?

  The half cell is more likely to be oxidized
• What does a positive electrode potential indicate?

  The half cell is more likely to be reduced
• What is the importance of knowing which half cell is reduced and which is oxidized?

  It helps predict the direction of electron flow
• What acronym is used to remember the rules of electrode potentials?

  NO PRoblem
• What does the acronym "no problem" refer to in electrochemistry?

  Most negative half cell undergoes oxidation
• What does oxidation involve in terms of electrons?

  Oxidation is the loss of electrons
• What is the acronym used to remember oxidation and reduction?

  Oil-Rig
• How do you represent the oxidation of zinc in an equation?

  Zinc forms $Zn^{2+} +$$2e^{-}$
• What is the full cell reaction when zinc and copper half cells are combined?

  Zn + Cu$^{2+} \rightarrow Zn^{2+} +$$Cu$
• What is the standard hydrogen electrode used for?

  To measure standard electrode potential
• What are the standard conditions for a standard hydrogen electrode?

  298 K, 100 kPa, 1 mol/dm³ H+
• Why is it important to have a reference electrode like the standard hydrogen electrode?

  It allows global comparison of electrode potentials
• What is the concentration of H+ ions required in the standard hydrogen electrode setup?

  1 mol/dm³
• What happens if sulfuric acid is used instead of hydrochloric acid in the setup?

  It produces more H+ ions
• What does the electrochemical series represent?

  A list of half cell reactions and potentials
• What does a positive value in the electrochemical series indicate?

  Reaction is likely to occur
• How do you identify a reducing agent in the electrochemical series?

  It is on the right side of the equation
• What is the most powerful oxidizing agent in the electrochemical series?

  Chlorine
• What is the formula to calculate standard cell potential?

  $E^{\circ}_{cell} =$$E^{\circ}_{reduced} - E^{\circ}_{oxidized}$
• How do you remember the order of reduction and oxidation in the formula?

  Redox: reduction first, then oxidation
• What is the most powerful reducing agent in the electrochemical series?

  Magnesium
• What does a negative value in the electrochemical series indicate?

  Reaction is unlikely to occur
• What is the significance of the electrochemical series in reactions?

  It helps identify oxidizing and reducing agents