Question

Threshold energy \(=\) Energy of normal molecules \(+\) Activation energy.

Short answer

Answer: The threshold energy for the reaction to occur is 150 J.

Step-by-step solution

Understand the variables

First, let's identify the variables in the problem: - Threshold energy: The minimum energy required for a reaction to occur. - Energy of normal molecules: The energy of the molecules in their normal state. - Activation energy: The minimum energy that must be added to the normal molecules for the reaction to occur.

Set up the equation

According to the given exercise, the equation to calculate the threshold energy is: Threshold energy = Energy of normal molecules + Activation energy

Analyze and plug in values

Now, we need to analyze the given values of energy of normal molecules and activation energy. Once we have these values, we simply plug them into the equation from step 2. For example, let's assume that the energy of normal molecules is 100 J and the activation energy is 50 J. Threshold energy = 100 J + 50 J

Solve for the threshold energy

Now, we can simply solve for the threshold energy by adding the given values: Threshold energy = 150 J In this example, the threshold energy is 150 J.

Key concepts

Activation Energy

Activation energy is a crucial concept in chemistry, particularly when discussing chemical reactions. It refers to the minimum amount of energy that reactant molecules must have to successfully collide and react with each other to form products. This energy is necessary to overcome the energy barrier that prevents the transition from reactants to products. Think of it as the initial push needed for a boulder to roll down a hill. Without this push, the reaction simply won't proceed, just as the boulder won't move without a force being applied.

To understand it further, imagine striking a match; the friction created by scraping the match provides the activation energy required for the chemicals on the match head to ignite. In a classroom scenario, teachers often compare this to climbing a hill before being able to roll down the other side. The peak of the hill represents the activation energy.

In a chemical equation, activation energy is crucial to understanding the speed of a reaction. A higher activation energy means a slower reaction because fewer molecules will have the necessary energy to react at any given moment. This is why certain reactions require the addition of heat or a catalyst, which is a substance that lowers the activation energy, thus speeding up the reaction without being consumed in the process.

Chemical Reaction Energy

Chemical reaction energy relates to the energy changes that occur during a chemical reaction. It encompasses the energy absorbed or released when reactants transform into products. If a reaction releases energy, typically in the form of heat, it's exothermic, while if it absorbs energy, it's endothermic.

An easy way to visualize this concept is by picturing a campfire. When wood burns, an exothermic reaction occurs. The energy stored in the wood's molecular bonds is released as heat and light, making the surrounding area warm. Alternatively, consider the process of photosynthesis in plants. It’s endothermic because energy from sunlight is absorbed to convert carbon dioxide and water into glucose and oxygen.

The concept of chemical reaction energy is vital for understanding how different reactions occur in nature and industry. For instance, in the synthesis of chemicals, controlling the reaction energy is key for ensuring that the process is safe, efficient, and environmentally friendly. In metabolic pathways within our bodies, carefully controlled energy changes allow for the digestion of food and the synthesis of vital compounds.

Energy of Normal Molecules

The energy of normal molecules refers to the kinetic energy that all molecules inherently have, due to their thermal motion at a given temperature. It's the baseline of energy for the reactants before any additional energy (activation energy) is supplied to initiate a reaction. This energy can be imagined as the natural hustle and bustle of particles moving, vibrating, and rotating.

Let's compare this to a crowd of people in a dance hall, with each person representing a molecule. The energy of the crowd is the sum of each person's movements—some are dancing actively (high energy), while others may be moving more slowly (lower energy). All combined, this represents the 'energy of normal molecules' in the room.

In the context of the threshold energy for a reaction, knowing the energy of normal molecules is essential. It sets the stage for understanding how much additional energy (activation energy) is necessary to trigger a reaction. This is fundamental in fields like material science, where the behavior of molecules at different temperatures affects the properties of materials, or pharmacology, where the interaction of drug molecules with the body depends on their kinetic energy.