Engineering Chemistry DCH002A Exam

The electrode potential is a measure of the tendency of an electrode to lose or gain electrons when in contact with an electrolyte. It is a key concept in electrochemistry and is used to predict the direction of electron flow in electrochemical reactions.

The bottom-up approach in nanoparticle synthesis involves building up nanoparticles from smaller building blocks like atoms or molecules. It's like constructing a house brick by brick. The building blocks are carefully controlled, and the process happens in a controlled environment.

Sacrificial anodic protection uses a metal with a lower electrode potential than the protected metal. This sacrificial metal corrodes away, acting as an anode, while the protected metal becomes the cathode and remains unharmed. It's like a sacrificial shield protecting the main structure.

Nanotechnology plays a role in water purification by using nanoparticles to remove contaminants like heavy metals and organic pollutants. These tiny materials act like filters, trapping pollutants effectively.

Oxidative corrosion happens when metal reacts with oxygen in the presence of moisture, forming metal oxides. Cathodic reactions consume electrons from the metal's surface, while anodic reactions release metal ions into the environment. The protective oxide layer can either hinder or promote further corrosion, depending on its properties.

Nanomaterials are classified based on their dimensions: 0D - Nanoparticles, 1D - Nanowires/Nanorods, 2D - Nanosheets, 3D - Nanoframes. This classification helps understand their properties and applications.

The flash point of a lubricant is the lowest temperature at which the lubricant's vapors will ignite in the presence of an ignition source. It indicates the temperature at which a fire hazard exists when handling the lubricant.

The fire point of a lubricant is the lowest temperature at which the lubricant will sustain combustion after ignition. It is usually a few degrees higher than the flash point. This point indicates the temperature where the lubricant will continue to burn once ignited.

The flash point and fire point are important safety parameters for lubricants. They help determine storage and handling conditions, and prevent accidental fires or explosions.

Water disinfection using bleaching powder involves adding calcium hypochlorite (Ca(OCl)2) to water. The chlorine released from bleaching powder kills harmful microorganisms like bacteria and viruses. The process is effective in disinfecting water and making it safe to drink.

Lubrication is the process of reducing friction and wear between surfaces in contact, typically by introducing a lubricant (such as oil or grease) between those surfaces.

Thin film lubrication occurs when a thin layer of lubricant completely separates the moving surfaces. The lubricant film provides a hydrodynamic wedge, reducing direct contact between the surfaces and minimizing friction and wear. This is achieved by the lubricant's viscosity and the relative motion of the surfaces.

The cloud point of a lubricant is the temperature at which the lubricant starts to become cloudy or opaque. This is due to the wax or other components in the lubricant becoming less soluble at lower temperatures.

The pour point of a lubricant is the lowest temperature at which the lubricant remains pourable. It's a crucial parameter for handling and storage in cold environments.

Rusting is an electrochemical corrosion process where iron reacts with oxygen and water to form iron oxide (rust). It involves two half-reactions: anodic oxidation of iron and cathodic reduction of oxygen. The anodic reaction releases iron ions (Fe²⁺) into the electrolyte, while the cathodic reaction consumes electrons, leading to the formation of hydroxide ions (OH⁻). These ions then react with iron ions to form iron oxide (Fe₂O₃.xH₂O, rust).

Nanoparticles are tiny particles with at least one dimension in the nanometer range (1-100 nm). These particles exhibit unique properties due to their size, such as high surface area, quantum effects, and enhanced reactivity.

Carbon nanowires are one-dimensional nanomaterials consisting of long, thin chains of carbon atoms. They exhibit high electrical conductivity, thermal conductivity, and strength due to their unique structure and bonding. They are used in electronics, sensors, and energy storage applications.

Fullerenes are cage-like molecules made entirely of carbon atoms. They have a spherical or ellipsoidal shape, with many different possible structures. These molecules have unique electronic and mechanical properties, making them valuable for applications in electronics, medicine, and materials science.

The amount of dissolved calcium and magnesium salts in water. Measured in ppm (parts per million) or mg/L.

A type of water hardness caused by dissolved magnesium and calcium bicarbonates. It can be removed by boiling or adding lime.

A type of water hardness caused by dissolved magnesium and calcium sulfates and chlorides. It cannot be removed by boiling.

The amount of heat energy released when a unit mass of fuel is burned completely.

The highest calorific value obtained when all the products of combustion are cooled to room temperature.

The lower calorific value (LCV) is the amount of heat released if the water vapor formed during combustion is not condensed, and the heat it carries is not recovered.

A process where a metal reacts with its surrounding environment, usually oxygen and water, leading to its deterioration and loss of functionality.

A technique used to prevent corrosion by coating the metal surface with a protective layer of another metal. Examples include galvanizing and tin plating.