Question

The rate of a reaction usually (a) increases with increase in temperature (b) decreases with increase in temperature (c) remains unaffected with increase in temperature (d) none of these

Short answer

(a) increases with increase in temperature

Step-by-step solution

Understanding Chemical Kinetics

Chemical kinetics is the study of the speed or rate of a chemical reaction under various conditions. By altering different physical conditions like temperature, pressure and concentration, we can observe different rates of reactions.

Understanding the Effect of Temperature on Reaction Rate

According to the Collision Theory, for a reaction to occur, particles must collide with enough energy and in the correct orientation. As the temperature increases, the kinetic energy of the particles also increases. This means they move faster, and the frequency of collisions increases, resulting in an increased rate of reaction.

Analyzing the Options

Given this information, we can analyze the answer choices. (a) states that the rate of reaction increases with increase in temperature, which aligns with our understanding. (b) and (c) don't align with the discussed principles of chemical kinetics. (d) is also incorrect because the effect of temperature on the rate of reaction is a well-established principle.

Key concepts

Reaction Rate

In chemical kinetics, the reaction rate is a fundamental concept that tells us how fast or slow a chemical reaction occurs. This speed is determined by how quickly reactants are converted into products. The reaction rate can be measured by the change in concentration of reactants or products per unit time. Thus, if a reaction proceeds quickly, it has a high reaction rate, whereas a slow reaction is characterized by a low reaction rate.
Several factors can influence the reaction rate:

• Concentration of Reactants: A higher concentration usually leads to a higher reaction rate because more reactant particles are available to collide and react.
• Surface Area: Increasing the surface area of a solid reactant increases the reaction rate by providing more area for collisions.

Understanding the reaction rate is crucial for controlling chemical processes in everything from industrial manufacturing to biological systems.

Collision Theory

Collision theory offers a simple yet powerful explanation for why chemical reactions occur. It postulates that for a reaction to happen, reactant particles must collide. However, not all collisions result in a reaction. The theory specifies two critical conditions:

• Sufficient Energy: Upon collision, particles must possess enough energy to surpass the activation energy barrier, which is the minimum energy required for the reaction to proceed.
• Proper Orientation: Colliding particles must also be aligned correctly, with specific parts of the molecules interacting, for a successful reaction.

The frequency and nature of these collisions determine the reaction rate. Simply, more effective collisions lead to a higher reaction rate. As such, manipulating conditions to enhance collision energy and increase collision frequency is key in accelerating chemical reactions.

Temperature Effect on Reactions

Temperature plays a vital role in the rate of chemical reactions. According to the collision theory, as the temperature increases, so does the kinetic energy of the particles involved in the reaction. This increase in kinetic energy has significant implications:

• Faster Movement: Higher temperatures cause particles to move faster, which increases the frequency of collisions.
• Greater Energy: More particles have enough energy to exceed the activation energy, leading to more successful collisions.

These effects mean that generally, as temperature rises, the reaction rate increases. This principle is frequently observed in everyday life, such as when cooking food faster at higher temperatures or using refrigerators to slow down food spoilage. Understanding the effect of temperature on reaction rates is crucial for optimizing and controlling chemical reactions in a variety of settings.