Module 5: Redox and Electrode Potentials V1 Flashcards
Write a balanced half equation for the oxidation of manganate(VII) ions to manganese(II) ions in acidic conditions.
Yeah, you have to remember this transformation.
Write a balanced half equation for the reduction of Iron(II) ions to Iron(III) ions in acidic conditions.
Yeah, you have to remember this transformation.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write half equations under acidic conditions for the following. State whether the substance is being oxidised or reduced.
Write an overall redox equation using the two half-equations given.
Write half equations followed by the redox equation under acidic conditions for the following.
Write half equations followed by the redox equation under acidic conditions for the following.
Write half equations followed by the redox equation under acidic conditions for the following.
Write half equations followed by the redox equation under acidic conditions for the following.
What is the oxidising agent in manganate (VII) redox titrations
Manganate (VII) ions ✓
In manganate (VII) redox titrations, what solution is normally placed in the burette?
A solution containing Manganate (VII) ions is placed in the burette. ✓
i.e. potassium manganate ✓
Explain why Fe2+ pipetted into the conical flask with excess sulfuric acid in manganate (VII) redox titrations
To ensure acidic conditions ✓
Explain why Fe2+ pipetted into the conical flask with excess sulfuric acid instead of excess hydrochloric acid in manganate (VII) redox titrations
State the colour of Manganate (VII) ions
Purple. ✓
State the colour of manganese (II) ions
Pink. ✓
State the colour of the end-point in Manganate (VII) redox titrations
Pale pink. ✓
Suggest why the end point can appear colourless in Manganate (VII) redox titrations
Dilute solutions used. ✓
In thiosulfate/iodine redox titrations, what solution is normally placed in the burette?
Solution containing thiosulfate is placed in the burette. ✓
i.e. sodium thiosulfate ✓
In thiosulfate/iodine redox titrations what is normally placed in the conical flask containing Cu(II) ions (or other chemicals)
Excess I- is next added to the conical flask. ✓
i.e. KI ✓
A student is conducting a thiosulfate/iodine redox titration. What is the molar ratio of thiosulfate: iodine: copper(II) ions he needs to remember
2:1:2. ✓
Not always given in the exam.
Define what is meant by “Standard electrode potential of a half cell” and give the symbol for this.
State the standard conditions used in half-cells.
don’t forget H+
Define what is meant by “The standard electrode potential of a half-cell “
is the electromotive force (emf) of a half-cell ✓
compared with the standard hydrogen half-cell ✓
measured at 298K and 100kPa. ✓
State the value of the electrode potential, for the standard hydrogen half-cell.
Write the equation for the electrode potential, E⦵, of hydrogen.
Draw a labelled half-cell for the standard hydrogen electrode.
Below is a diagram of an electrochemical cell.
What are the charge carriers in the wire?
What are the charge carriers in the salt-bridge?
Wire: electrons
Salt-bridge: Ions
Give the equation required to calculate the cell potential
Draw a labelled diagram based on the redox systems shown below.
Write the overall cell reaction for the following two redox systems.
Calculate the cell potential, for the electrochemical cell comprising of the two redox systems below
Using the data given state and explain whether Cu will reduce Zn2+ to Zn?
Will magnesium reduce copper (II) ions to copper? Suggest reasons why the reaction may not take place? Calculate the cell potential. The cell potential slowly changed, why.
In an acid hydrogen fuel cell. State the transformation at the electrodes. Write half-equations for each transformation and combine the half equations to make an overall equation.
In an alkali hydrogen fuel cell. State the transformation at the electrodes. Write half-equations for each transformation and combine the half equations to make an overall equation.
Modern fuel cells are being developed as an alternative to the direct use of fossil fuels. The ‘fuel’ can be hydrogen but many other substances are being considered.
In a methanol fuel cell, the overall reaction is the combustion of methanol catalysed by an acid catalyst.
As with all fuel cells, the fuel (methanol) is supplied at one electrode and the oxidant (oxygen) at the other electrode.
Oxygen reacts at the negative electrode of a methanol fuel cell to produce water.
Methanol reacts at the positive electrode to produce carbon dioxide.
Write half-equations for the redox processes at each electrode and then, an overall equation.
remember, to multiply for electrons to balance, cancel then simplify
