Learning Materials
Features
Discover
When baking a cake, energy from the oven gets absorbed by the ingredients, leading to bond formation and a more orderly product. Potential energy graphs are probably the best way to illustrate the energy changes that happen in chemical reactions, as it tells chemists what happens when energy is released or absorbed.
Millions of flashcards designed to help you ace your studies
Sign up for free____ energy is the energy available as stored energy.
The activation energy is the energy required to _____ the reaction.
During chemical reactions, heat may be ______.
______ are those reactions that release energy to the surroundings.
In exothermic reactions, the potential energy of the products is ____ than the potential energy of the reactants.
The change in enthalpy (ΔH) of exothermic reactions is ______.
Photosynthesis is an example of a ______ reaction.
_______ are chemical reactions that absorb energy.
True or false: Potential energy graphs shows the energy changes occuring in a chemical reaction
Endothermic reactions have a positive ΔH and the potential energy of the products tend to be _____ than that of the reactants.
____ is the energy produced by motion.
____ energy is the energy available as stored energy.
The activation energy is the energy required to _____ the reaction.
During chemical reactions, heat may be ______.
______ are those reactions that release energy to the surroundings.
In exothermic reactions, the potential energy of the products is ____ than the potential energy of the reactants.
The change in enthalpy (ΔH) of exothermic reactions is ______.
Photosynthesis is an example of a ______ reaction.
_______ are chemical reactions that absorb energy.
True or false: Potential energy graphs shows the energy changes occuring in a chemical reaction
Endothermic reactions have a positive ΔH and the potential energy of the products tend to be _____ than that of the reactants.
____ is the energy produced by motion.
Achieve better grades quicker with Premium
Geld-zurück-Garantie, wenn du durch die Prüfung fällst
Did you know that StudySmarter supports you beyond learning?
Review generated flashcards
Start learning or create your own AI flashcards
Team Potential Energy Diagram Teachers
Before diving into chemical potential energy diagrams, we need to remember the difference between kinetic and potential energy. Kinetic energy is the energy produced by motion, whereas potential energy is the energy available as stored energy within an object, like a molecule, due to the configuration of its parts or atoms.
We also need to review the basic concept of exothermic and endothermic reactions. In order for a reaction to occur, the collision between reaction particles must be energetic, and this energy is known as activation energy.
The activation energy is the energy required to initiate the reaction.
During a chemical reaction, heat may be released or absorbed. If energy is released, we call it an exothermic reaction.
Exothermic reactions are those reactions that release energy into the surroundings.
In exothermic reactions, the potential energy of the products is lower than the potential energy of the reactants. Because of this, the change in enthalpy (ΔH) is negative.
Enthalpy (ΔH) is defined as the total energy change in the system. It can be calculated using the following equation: \(\Delta H = H_{product} - H_{reactant} \)
Endothermic reactions, on the other hand, are those chemical reactions that absorb energy. These reactions have a positive ΔH and the potential energy of the products tend to be higher than that of the reactants.
Endothermic reactions are reactions that absorb energy from the surroundings to the reacting substances.
When dealing with chemical reactions, chemists use potential energy diagrams (or reaction coordinate diagrams) to show the potential energy in a chemical reaction.
Figure 1 shows a simple example of a potential energy graph for an exothermic reaction. Here, the x-axis is labeled as the reaction coordinate or time, while the y-axis is labeled as the potential energy.
Figure 1. Potential energy diagram for an exothermic reaction, Isadora Santos - Vaia Originals.
However, sometimes we may encounter chemical reactions involving more than one elementary step. In this case, we would have a multi-step reaction coordinate diagram (figure 2). The figure below shows the potential energy diagram for a multi-step reaction mechanism. Notice that the first step in this chemical reaction is endothermic, whereas the second step is exothermic.
Figure 2. Multi-step reaction coordinate diagram, Isadora Santos - Vaia Originals.
To learn more about this, or if you need a refresher, check out "Elementary Reactions" and "Multistep reactions"!
Let's look at a problem!
By looking at the potential energy graph below, what can you conclude about the reaction?
$$ \text{2 K} \text{ + }\text{S} \to \text{ K} _{2}\text{S} $$
Figure 3. Potential energy diagram for a chemical reaction involving potassium (K) and sulfur (S) ,Isadora Santos - Vaia Originals.
Which of the following choices is true
a. The reaction is a type of synthesis reaction, and it is exothermic.
b. The reaction is a type of decomposition reaction, and it is endothermic.
c. The reaction is a type of synthesis reaction, and it is endothermic.
d. The reaction is a type of decomposition reaction, and it is exothermic.
The first thing you need to do is decide whether the chemical reaction is a type of synthesis or decomposition reaction. Remember that a synthesis reaction involves combine two or more substances to make a new product, while in a decomposition reaction, we break apart one substance into two or more different products. In this case, we are joining 2K + S to form K2S, and therefore we have a synthesis reaction.
Now, take a look the potential energies for the reactants and the products in figure 3. Since the products have less potential energy than the reactants, we can say that is it an exothermic reaction.
So, the correct answer is a.
Now that we know how a potential energy diagram is labeled, let's look at the potential energy diagram for an endothermic reaction, which are reactions that absorb energy, and as a result, the temperature of the reaction mixtures in the solution decreases.
Figure 4 shows the potential energy diagram for the endothermic reaction for the decomposition of magnesium oxide (MgO). As expected for an endothermic reaction, notice that the products (2 Mg + O2) possess more potential energy than the reactants (2 MgO).
$$ \text{2 MgO + energy} \to \text{2 Mg} \text{ + }\text{O}_{2} $$
Figure 4. Potential Energy Diagram for an endothermic reaction, Isadora Santos - Vaia Originals.
If we were looking at the synthesis of MgO instead, we would have a potential energy diagram for an exothermic reaction, and the potential energy of the reactants would be higher than the PE of products. $$ \text{2 Mg} \text{ + }\text{O}_{2} \to \text{2 MgO + energy} $$
Another interesting example of an endothermic reaction is photosynthesis. Photosynthesis is the process of using sunlight energy to make food (glucose) from water and carbon dioxide. During photosynthesis, light energy gets converted to chemical energy.
$$ \text{6 CO}_{2} \text{ + 6 H}_{2}\text{O} \to \text{C}_{6}\text{H}_{12}\text{O}_{6}\text{ + O}_{2} $$
Figure 5. Potential Energy graph for Photosynthesis, Isadora Santos - Vaia Originals.
When catalysts are present, they create an alternate reaction pathway with lower activation energy (figure 6). This reduction in the activation energy also increases the rate of the reaction exponentially.
All Catalysts increase the rate of reaction without getting used in the reaction. Catalysts, lower the activation energy by creating an alternate reaction pathway.
Figure 6. Potential energy diagram for a chemical reaction with and without the presence of a catalyst, Isadora Santos - Vaia Originals.
A common example of a catalyst is an enzyme. Enzymes are proteins that act as catalysts in biochemical reactions. For example, carbonic anhydrase is an enzyme that can catalyze the synthesis of carbonic acid, from carbon dioxide and water, when the CO2 concentration in the body is too high. This regulation of CO2 concentration by the enzyme helps keep the body's pH balanced.
Figure 7 shows the potential energy diagram for this reaction. Notice that, when the enzyme carbonic anhydrase is present, less activation energy is needed to initiate the reaction. However, it does not change the ΔH of the reaction as it does not get used up.
Figure 7. Potential energy diagram for the reaction between CO2 and H2O to form H2CO3, Isadora Santos - Vaia Originals.
Want to learn more about enzymes and other types of catalysts? Check out "Catalysts"!
Lastly, let's talk about electric potential energy. Electric potential energy is the potential energy ("stored" energy) a charge has when moved by an electrostatic force. We can use the formula below to calculate electric potential energy.
$$ U = k\frac{q_{1}\times q_{2}}{r} $$
Where,
Figure 8 Shows the diagram of electric potential. The x-axis shows the distance away from the charge, and the Y-axis shows the electric potential at a certain point.
Figure 8. Electric potential energy diagram, Isadora Santos, Vaia Originals.
Electric potential energy is mostly applied to physics, so you should always check with your chemistry professor about whether you should remember this formula for your exam!
Sign up for free to gain access to all our flashcards.
Which diagram represents the potential energy of an exothermic reaction?
The potential energy diagram of an exothermic reaction will show the potential energy of the products as lower than the potential energy of the reactants.
What does a potential energy diagram show?
A potential energy diagram shows the potential energy involved in a chemical reaction, and how this energy energy gets absorbed or released.
How to draw a potential energy diagram?
To draw a potential energy diagram we can label x-axis as the reaction coordinate or time, and the y-axis as the potential energy.
What is a potential energy diagram?
A potential energy diagram is a diagram that shows the release and absorption of potential energy during a chemical reaction.
What is an example of potential energy diagram for a reaction?
An example of potential energy diagram for a reaction is the exothermic potential energy graph showing the potential energy is the reaction between potassium (K) and sulfur (S).
At StudySmarter, we have created a learning platform that serves millions of students. Meet the people who work hard to deliver fact based content as well as making sure it is verified.
Lily Hulatt is a Digital Content Specialist with over three years of experience in content strategy and curriculum design. She gained her PhD in English Literature from Durham University in 2022, taught in Durham University’s English Studies Department, and has contributed to a number of publications. Lily specialises in English Literature, English Language, History, and Philosophy.
Get to know Lily
Gabriel Freitas is an AI Engineer with a solid experience in software development, machine learning algorithms, and generative AI, including large language models’ (LLMs) applications. Graduated in Electrical Engineering at the University of São Paulo, he is currently pursuing an MSc in Computer Engineering at the University of Campinas, specializing in machine learning topics. Gabriel has a strong background in software engineering and has worked on projects involving computer vision, embedded AI, and LLM applications.
Get to know Gabriel
Vaia is a globally recognized educational technology company, offering a holistic learning platform designed for students of all ages and educational levels. Our platform provides learning support for a wide range of subjects, including STEM, Social Sciences, and Languages and also helps students to successfully master various tests and exams worldwide, such as GCSE, A Level, SAT, ACT, Abitur, and more. We offer an extensive library of learning materials, including interactive flashcards, comprehensive textbook solutions, and detailed explanations. The cutting-edge technology and tools we provide help students create their own learning materials. StudySmarter’s content is not only expert-verified but also regularly updated to ensure accuracy and relevance.
Learn moreSave explanations to your personalised space and access them anytime, anywhere!
Sign up with Email Sign up with AppleBy signing up, you agree to the Terms and Conditions and the Privacy Policy of Vaia.
Already have an account? Log in
Sign up to highlight and take notes. It’s 100% free.
Explanations 
Textbooks 
Exams 
GCSE 
IGCSE 
AS 
A Level 
International A Level 
University Admissions Tests 
Flashcards 
Vaia AI 
Notes 
Study Plans 
Study Sets 
Find a job 
Find a degree 
Student Deals 
Magazine 
Mobile App 
