Fun Facts for Electrochemistry

What can nitrogen do, and where is it used?

Nitrogen can have oxidation states from -3 to +5 and is used in a variety of applications including explosives, fertilizers produced via the Haber process, laughing gas (N₂O), medications like Viagra, and is also associated with urban smog.

Why is phosphorus important?

Phosphorus plays a crucial role in biochemistry, being a component of DNA and RNA, and is commonly found in fertilizers and soaps. Excess phosphate in aquatic environments can lead to harmful algae blooms, disrupting ecosystems.

What are halogens like?

Halogens are characterized by their small atomic size, high electronegativity, and tendency to form -1 ions. Chlorine (Cl₂), one of the most notable halogens, is widely used in the production of PVC and for disinfection purposes.

How is sulfuric acid (H₂SO₄) made and used?

Sulfuric acid is produced via the Claus process (converting hydrogen sulfide to sulfur) and the Contact process (oxidation of sulfur to H₂SO₄). Approximately half of the produced sulfuric acid is used to convert phosphate rock into phosphoric acid (H₃PO₄) for fertilizers.

Galvanic vs. Electrolytic cells?

Galvanic cells generate electrical energy through spontaneous chemical reactions (E > 0), typically used in batteries. Electrolytic cells, on the other hand, require an external energy source to drive non-spontaneous reactions (E < 0), such as during the charging of batteries.

In Zn|Zn²⁺||H⁺|H₂|Pt, what happens?

In this electrochemical cell, the zinc anode undergoes oxidation and loses mass, while hydrogen ions (H⁺) at the platinum cathode gain electrons to form hydrogen gas (H₂), resulting in an increase in pH.

Electrolysis of molten ZnF₂ + LiCl?

During the electrolysis of molten zinc fluoride (ZnF₂) mixed with lithium chloride (LiCl), zinc is deposited at the cathode due to its higher reduction potential, while chlorine gas (Cl₂) evolves at the anode as it is more easily oxidized.

What does the E° table tell you?

The E° table indicates standard electrode potentials; for example, fluorine (F₂) is identified as the strongest oxidizing agent (+3V) while lithium (Li) is the strongest reducing agent. Coinage metals like copper (Cu), silver (Ag), and gold (Au) are less reactive and often found higher on the table.

Nernst equation and batteries?

The Nernst equation, E = E° - (0.06/n) log Q, relates the cell potential to the concentration of reactants and products. A charged battery will have a potential (E) greater than its standard potential (E°), whereas a dead battery will have E approaching zero due to equilibrium (Q = K).

Which metals react with water or acid?

Group I metals typically react with cold water, Group II metals react with steam, and transition metals react with acids. Precious metals like copper (Cu), silver (Ag), and gold (Au) do not react with water or acids.

Types of batteries?

1. Primary (disposable) batteries: Alkaline (used in household devices), Zinc-air (used in hearing aids). 2. Secondary (rechargeable) batteries: Lithium-ion (found in smartphones and electric cars), Nickel-Cadmium (for household use), Lead-acid (commonly used in cars).

Why are Li-ion batteries risky?

Lithium-ion batteries can be hazardous as they are liable to catching fire under certain conditions and are therefore banned on planes when carried as cargo.

How to stop rust?

To prevent rusting of iron, techniques such as galvanization (coating with zinc), using magnesium as a sacrificial metal, or employing stainless steel (which contains chromium) can be effective.

Atom economy example:

In the reaction 2C₆H₅CO₂H + O₂ → 2C₆H₅OH + 2CO₂, atom economy (AE) is calculated as (188/276) × 100, resulting in an AE of 68%, indicating efficiency in producing desired products.

What decides electrolysis products?

The products of electrolysis are determined by the species that are easiest to reduce at the cathode and the species that are easiest to oxidize at the anode.

Why use platinum (Pt) in cells?

Platinum is chosen as an electrode material in electrochemical cells because it is inert and does not participate in the electrochemical reactions, thereby serving effectively as a conductor of electrons.

What happens to pH at the cathode?

At the cathode, hydrogen ions (H⁺) are converted to hydrogen gas (H₂), resulting in a decrease in the concentration of H⁺ ions, which leads to an increase in pH (making the solution more basic).

Salt bridge purpose?

The purpose of the salt bridge in electrochemical cells is to allow the flow of ions between the two half-cells, helping to maintain charge balance as the redox reactions proceed.

Metal Activity Series?

In the metal activity series, more active metals such as calcium (Ca) can displace less active metals like nickel (Ni) from their compounds during reactions.

Why are Cu, Ag, Au on the upper right of the E° table?

Copper, silver, and gold are located on the upper right of the E° table because they are stable, resistant to oxidation, and thus considered good oxidizing agents.

What’s atom economy (AE)?

Atom economy measures the efficiency of a reaction in transforming reactant atoms into product atoms, expressed as a percentage. A higher atom economy indicates less waste and more efficient utilization of resources.

Dead battery facts:

A dead battery is characterized by an electromotive force (E) of zero, meaning it has reached equilibrium, represented by Q being equal to the equilibrium constant (K).

What happens to E as a battery dies?

As a battery discharges and eventually dies, its electromotive force (E) decreases due to the accumulation of reaction products, leading to an increase in the reaction quotient (Q).

Why H₂ forms instead of Na in saltwater electrolysis?

During the electrolysis of saltwater, H₂ gas is produced instead of sodium metal (Na) because hydrogen ions (H⁺) are easier to reduce than sodium ions (Na⁺), given their respective standard reduction potentials.

Haber process?

The Haber process synthesizes ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂) gas, operating under high temperature and pressure conditions for agricultural fertilizers.

Why limit phosphates?

Phosphates should be limited in aquatic systems because they can lead to algae blooms, a phenomenon known as eutrophication, which disrupts aquatic ecosystems by depleting oxygen.

Anode’s job in any cell?

The anode in an electrochemical cell is responsible for oxidation processes, losing electrons as reduction takes place at the cathode.

Primary vs. secondary batteries?

Primary batteries are designed for single-use and cannot be recharged, whereas secondary batteries contain components that allow them to be recharged and reused multiple times.

Stainless steel doesn’t rust because…

Stainless steel does not rust due to the presence of chromium, which forms a protective oxide layer that prevents further oxidation.

What is the SHE?

The Standard Hydrogen Electrode (SHE) is a reference electrode defined to have a potential of 0 volts, serving as a benchmark for measuring the standard electrode potentials (E°) of other half-reactions, under standard conditions (1M H⁺ concentration, 1 atm hydrogen gas).