Endothermic, Exothermic & Rates Of Reaction

Exothermic refers to a process or reaction that releases heat to its surroundings. This means that during an exothermic reaction, the system loses heat energy, resulting in an increase in the temperature of the surroundings. Examples of exothermic reactions include combustion, such as burning wood or gasoline, where heat is released as a byproduct.

The hull of an ocean-going ship rusts quickly because sea water speeds up the reaction of iron rusting. Sea water contains dissolved salts and minerals, which act as electrolytes and enhance the corrosion process. This accelerates the oxidation of iron, leading to the formation of rust. Additionally, the constant exposure to moisture and saltwater creates an ideal environment for rust to develop and spread rapidly on the ship's hull.

Increasing the temperature of a reaction provides more energy to the particles involved. This increase in energy causes the particles to move faster and collide with each other more frequently. As a result, the chances of successful collisions, where the particles react, are increased. Additionally, the collisions become more forceful, as the increased energy leads to stronger impacts. Therefore, the rate of reaction speeds up when the temperature is increased.

A catalyst is a substance that increases the rate of a chemical reaction without being consumed or altered in the process. It provides an alternative pathway for the reaction to occur, lowering the activation energy required for the reaction to take place. This allows the reaction to proceed at a faster rate, but the catalyst itself remains unchanged and can be used repeatedly.

Powdered iron reacts faster than a lump of iron because the smaller particle size provides a larger surface area for the reactants to come into contact with each other. This increased surface area allows for more frequent and efficient collisions between the iron particles and the reactants, resulting in a faster reaction rate.

A metal with a bigger surface area reacts faster than a metal with a smaller surface area because more particles are exposed to collision with other particles. This increased surface area allows for a greater number of reactant particles to come into contact with each other, leading to a higher rate of reaction.

Melting is an endothermic reaction because it requires energy input to break the bonds between the solid particles and convert them into a liquid state. The energy is absorbed from the surroundings, causing a decrease in temperature. Therefore, melting is considered an endothermic process.

The factors affecting the rate of reaction are concentration, catalysts, surface area, and temperature. Concentration refers to the amount of reactants present, with higher concentrations leading to more collisions and increased reaction rates. Catalysts are substances that speed up reactions by lowering the activation energy required. Increasing the surface area of the reactants exposes more molecules to each other, resulting in more collisions and faster reactions. Temperature affects the rate by increasing the kinetic energy of the particles, leading to more frequent and energetic collisions.