R1.1.2 / R1.1.3 Exothermic and endothermic reactions

Summary

This video explains exothermic and endothermic reactions. Exothermic reactions release heat from the system to the surroundings, raising the temperature of the reaction mixture. Examples include combustion and neutralization. Endothermic reactions, on the other hand, absorb heat from the surroundings into the system, lowering the temperature of the mixture. Examples include photosynthesis and thermal decomposition. The video also discusses enthalpy changes, with exothermic reactions having negative enthalpy change (ΔH < 0) and endothermic reactions having positive enthalpy change (ΔH > 0).

Takeaways

• 🔥 Exothermic reactions release heat from the system to the surroundings.
• ❄️ Endothermic reactions absorb heat from the surroundings into the system.
• 🌡️ In an exothermic reaction, the temperature of the reaction mixture and surroundings increases.
• 🌱 Examples of exothermic reactions include combustion and neutralization.
• 📉 In an exothermic reaction, the change in enthalpy (Delta H) is negative, and the products are more stable than the reactants.
• 🌡️ In an endothermic reaction, the temperature of the reaction mixture and surroundings decreases as heat is absorbed.
• 🌿 Examples of endothermic reactions include photosynthesis and thermal decomposition.
• 📈 In an endothermic reaction, the change in enthalpy (Delta H) is positive, and the reactants are more stable than the products.
• ⚖️ In exothermic reactions, the products have lower enthalpy and are more energetically stable than the reactants.
• 🔄 In endothermic reactions, heat is absorbed from the surroundings, and the reactants have lower enthalpy than the products.

Q & A

What is the main focus of the video?

The main focus of the video is to explain exothermic and endothermic reactions, highlighting how heat flows between the system and the surroundings in each type of reaction.

What is the difference between the system and the surroundings in a chemical reaction?

The system consists of the reactants and products involved in the chemical reaction, while the surroundings include everything outside the system, such as the reaction mixture and the environment around it.

What happens to heat in an exothermic reaction?

In an exothermic reaction, heat flows from the system to the surroundings, causing an increase in the temperature of the reaction mixture and the surroundings.

Can you provide examples of exothermic reactions?

Examples of exothermic reactions include combustion and neutralization, such as when an acid and a base react and the temperature of the solution increases.

What does the enthalpy level diagram look like for an exothermic reaction?

In an exothermic reaction, the enthalpy change (ΔH) is negative, meaning the products have lower enthalpy than the reactants, making the products more energetically stable.

How does heat flow in an endothermic reaction?

In an endothermic reaction, heat flows from the surroundings into the system, resulting in a decrease in the temperature of the reaction mixture and the surroundings.

What are some examples of endothermic reactions?

Examples of endothermic reactions include photosynthesis and thermal decomposition reactions, where energy is absorbed from the surroundings.

What does the enthalpy level diagram show for an endothermic reaction?

In an endothermic reaction, the enthalpy change (ΔH) is positive, meaning the products have higher enthalpy than the reactants, making the reactants more energetically stable.

What is the key difference in enthalpy change between exothermic and endothermic reactions?

The enthalpy change (ΔH) in exothermic reactions is negative, indicating heat release, while in endothermic reactions, it is positive, indicating heat absorption.

Which is more energetically stable: the products of an exothermic reaction or the reactants of an endothermic reaction?

In an exothermic reaction, the products are more energetically stable, whereas in an endothermic reaction, the reactants are more energetically stable.

Outlines

00:00

🔥 Introduction to Exothermic and Endothermic Reactions

In this video, we explore two types of chemical reactions: exothermic and endothermic. Exothermic reactions transfer heat from the system to the surroundings, while endothermic reactions absorb heat from the surroundings into the system. Before diving into the details, it's essential to understand the distinction between the 'system'—comprising reactants and products—and the 'surroundings,' which include everything outside the reaction mixture.

🌡️ Exothermic Reactions Explained

Exothermic reactions release heat from the system to the surroundings, causing the temperature of both the reaction mixture and the surroundings to increase. Common examples include combustion and neutralization. In a neutralization reaction, for instance, mixing an acid and base results in a temperature rise, indicating it’s exothermic. The enthalpy change (ΔH) for such reactions is negative, meaning the products have lower enthalpy and are more stable than the reactants.

🌿 Endothermic Reactions Explained

In contrast to exothermic reactions, endothermic reactions absorb heat from the surroundings into the system. This causes a temperature decrease in both the reaction mixture and surroundings. Examples include photosynthesis and thermal decomposition. In these reactions, the enthalpy change (ΔH) is positive, indicating that the products have higher enthalpy and are less stable compared to the reactants.

📊 Comparing Enthalpy and Stability in Reactions

The video wraps up by summarizing key differences between exothermic and endothermic reactions. In exothermic reactions, the enthalpy change (ΔH) is negative, the products have lower enthalpy and are more energetically stable. In endothermic reactions, the enthalpy change is positive, the reactants have lower enthalpy, and are more energetically stable. Additionally, heat is released in exothermic reactions and absorbed in endothermic reactions.

Keywords

💡Exothermic Reaction

An exothermic reaction is a chemical process where heat flows from the system to the surroundings, causing the temperature of the surrounding environment to increase. This is illustrated in the video with examples like combustion and neutralization reactions. In these reactions, the system releases energy, making the products more energetically stable than the reactants.

💡Endothermic Reaction

An endothermic reaction is a chemical process where heat is absorbed from the surroundings into the system, causing the surrounding environment to cool down. This concept is explained with examples such as photosynthesis and thermal decomposition. In an endothermic reaction, the reactants absorb heat, making the reactants more energetically stable than the products.

💡System

In thermodynamics, the 'system' refers to the reactants and products involved in the chemical reaction. The video defines the system as the focus of study, where heat exchange takes place, and distinguishes it from the surroundings, which is everything external to the system.

💡Surroundings

The surroundings refer to everything outside the chemical reaction system, including the reaction mixture and external environment. In exothermic reactions, heat is released to the surroundings, while in endothermic reactions, heat is absorbed from them.

💡Enthalpy

Enthalpy refers to the total heat content of a system. The video explains how changes in enthalpy, represented as Delta H, determine whether a reaction is exothermic (negative enthalpy change) or endothermic (positive enthalpy change).

💡Delta H

Delta H is the symbol for the change in enthalpy during a chemical reaction. In exothermic reactions, Delta H is negative, indicating a release of energy, while in endothermic reactions, Delta H is positive, indicating that energy is absorbed by the system.

💡Combustion

Combustion is a type of exothermic reaction where a substance reacts with oxygen, releasing heat and light. The video uses combustion as an example of an exothermic reaction to illustrate how heat is released from the system to the surroundings.

💡Neutralization

Neutralization is an exothermic reaction where an acid and a base react to form water and salt. The video mentions this process as an example of heat being released, increasing the temperature of the reaction mixture and the surroundings.

💡Photosynthesis

Photosynthesis is an example of an endothermic reaction, where plants absorb sunlight (energy) to convert carbon dioxide and water into glucose and oxygen. The video highlights this reaction as a demonstration of heat being absorbed into the system from the surroundings.

💡Thermal Decomposition

Thermal decomposition is an endothermic reaction in which a compound breaks down into simpler substances when heated. In the video, this process is mentioned as another example of a reaction that absorbs heat from the surroundings into the system.

Highlights

Introduction to exothermic and endothermic reactions

Definition of exothermic reactions where heat flows from the system to the surroundings

Definition of endothermic reactions where heat flows from the surroundings to the system

Explanation of the system and surroundings in a chemical reaction

Example of an exothermic reaction: Combustion and neutralization

Temperature increase in exothermic reactions

Enthalpy level diagram for exothermic reactions with negative ΔH

Products of exothermic reactions are more energetically stable

Example of an endothermic reaction: Photosynthesis and thermal decomposition

Temperature decrease in endothermic reactions

Enthalpy level diagram for endothermic reactions with positive ΔH

Reactants of endothermic reactions are more energetically stable

Summary of enthalpy change in exothermic reactions being negative

Summary of enthalpy change in endothermic reactions being positive

Heat release in exothermic reactions from system to surroundings

Heat absorption in endothermic reactions from surroundings to system

Transcripts

this is msj cem in this video I'll be

looking at exothermic and endothermic

reactions in this video we look at two

types of reactions exothermic reactions

in which heat flows from the system to

the surroundings and endothermic

reactions in which heat flows from the

surroundings into the system before we

look at these reactions in more detail

we need to know the difference between

the system and the

surroundings the system is the reactant

and the products the chemical reaction

the surroundings consist of everything

else outside of the system including the

reaction

mixture let's start by looking at

exothermic reactions in an exothermic

reaction heat flows from the system to

the

surroundings the temperature of the

reaction mixture in the test tube and

the surroundings increases as heat is

released examples of exothermic

reactions include combustion and neutral

ization in a neutralization reaction an

acid and a base are mixed in a test tube

and the temperature of the solution

increases therefore it's an exothermic

reaction next we look at an enthalpy

level diagram for an exothermic reaction

the Delta H that's the change in

enthalpy is negative or less than zero

the products have lower enthalpy than

the reactants and the products are more

energetically stable than reactants

next we look at endothermic reactions in

an endothermic reaction heat flows from

the surroundings to the system as you

can see this is the opposite of an

exothermic reaction in which heat is

released from the system to the

surroundings in an endothermic reaction

the temperature of the reaction mixture

and the surroundings decreases as heat

is absorbed examples of endothermic

reactions include photosynthesis and

thermal decomposition

reactions here we have an enthalpy level

diagram for an endothermic reaction the

Delta H that's the change in enthalpy is

positive or greater than zero the

reactants have lower enthalpy than the

products and the reactants are more

energetically stable than the

products let's end with a summary the

enthalpy change in an exothermic

reaction is negative for an endothermic

reaction it's positive which has lower

enthalpy in an ex exothermic reaction

it's the products in an endothermic

reaction it's the reactants which is

more energetically stable for an

exothermic reaction it's the products

for an endothermic reaction it's the

reactants and finally is heat absorbed

or released for an exothermic reaction

heat is released from the system to the

surroundings for an endothermic reaction

heat is absorbed from the surroundings

to the system