Redox Processes

Which of the following processes corresponds to a decrease in the oxidation number of an element?

What is the oxidation state of nitrogen in nitrous acid, $HNO_{2}$?

Which of the following elements commonly exhibits multiple positive oxidation states?

What is the oxidation state of bromine in the bromate ion, $BrO_{3}^{-}$?

A voltaic cell is constructed using a nickel electrode in a $1.0\ mol\ dm^{-3}$ solution of $Ni^{2+}(aq)$ and a copper electrode in a $1.0\ mol\ dm^{-3}$ solution of $Cu^{2+}(aq)$, as shown in the diagram below.

Given the standard reduction potentials: $Ni^{2+}(aq) + 2e^{-} \rightleftharpoons Ni(s) \quad E^{\theta} = -0.26\ V$ $Cu^{2+}(aq) + 2e^{-} \rightleftharpoons Cu(s) \quad E^{\theta} = +0.34\ V$

Which statement correctly describes the observations as the cell operates under standard conditions?

What is the standard reduction potential of the Standard Hydrogen Electrode (SHE)?

Which species is produced at the cathode during the electrolysis of molten $Al_{2}O_{3}$ in the Hall-Héroult process?

What is the oxidation state of Carbon in the oxalate ion, $C_{2}O_{4}^{2-}$?

In the reaction $O_{3} + 2I^{-} + H_{2}O \rightarrow O_{2} + I_{2} + 2OH^{-}$, which species is acting as the oxidizing agent?

Which of the following would produce the highest voltage in a voltaic cell under standard conditions?

What happens to the mass of the copper electrode in a $Zn-Cu$ voltaic cell as it operates?

Identify the species being reduced in the cell: $Zn(s) | Zn^{2+}(aq) || Cu^{2+}(aq) | Cu(s)$.

Which of the following is required for an electrolytic cell to function?

What is the charge of the cathode in a voltaic cell?

What is the correct cell notation for a cell where silver ions are reduced to silver metal and magnesium metal is oxidized to magnesium ions?

In a voltaic cell using $H_2/H^+$ and $Cu/Cu^{2+}$, hydrogen gas is bubbled over a platinum electrode. If $H_2$ is oxidized, what is the role of the platinum?

During the electrolysis of molten sodium bromide, which half-reaction occurs at the positive electrode?

In the electrolysis of dilute $H_2SO_4$, oxygen gas is produced at the anode. If the experiment is repeated using a very high current for a short duration, which observation would indicate that the process is following the stoichiometry of the decomposition of water?

An iron pipe can be protected from corrosion by connecting it to a block of magnesium. This is known as sacrificial protection. In this electrochemical setup, which of the following occurs?

A student investigates the electrolysis of concentrated aqueous sodium chloride (brine). They notice the solution near the cathode turns pink when phenolphthalein indicator is added. Which half-reaction at the cathode explains this observation?