An endothermic process is a reaction or physical change that absorbs heat from its surroundings. In Intro to Chemistry, that means the system takes in energy, so the surroundings usually cool down.
In Intro to Chemistry, an endothermic process is any chemical reaction or physical change that takes in heat from the surroundings. The system absorbs energy, so the surroundings lose that heat and usually get cooler to the touch.
The simplest way to picture it is a trade of energy. The particles in the system need extra energy to break attractions, spread out, or rearrange into products. That energy can come from the surroundings, which is why a beaker, cup, or your hand may feel cold when the process happens.
For a chemical reaction, the products end up at a higher energy level than the reactants. That is why the enthalpy change, , is positive for an endothermic process. You are putting energy in, and the system stores that energy in the new arrangement of atoms and bonds.
Endothermic does not mean a reaction is always fast or always impossible on its own. It only describes the direction of heat flow. A process can absorb heat and still happen if the overall energy conditions make it possible, or if another source keeps supplying energy.
A common Intro to Chemistry example is melting ice. The ice absorbs heat from the air, your skin, or the container as its particles move from a rigid solid lattice into a more mobile liquid. Evaporation works the same way, but with more energy needed to pull molecules into the gas phase. Photosynthesis is another familiar example, because plants absorb light energy to build glucose from carbon dioxide and water.
You will also see endothermic behavior in solution chemistry. Some dissolving processes absorb heat, so a temperature drop in the solution can be a clue that is positive. That is why a cold pack can get chilly when certain salts dissolve in water: the dissolution step is pulling heat from the mixture around it.
Endothermic process shows up anywhere Intro to Chemistry asks you to track energy flow. It connects thermochemistry, phase changes, and solution formation, so you can explain why something feels cold, why a reaction needs heating, or why a dissolving salt changes the temperature of water.
It also gives you the language for reading enthalpy problems correctly. If is positive, the process is endothermic, products sit at higher enthalpy than reactants, and energy has been absorbed by the system. That lets you interpret energy diagrams, compare reactions, and predict the sign of a heat change without guessing.
This term also matters when you study spontaneity. An endothermic process is not automatically impossible, because is only one part of the bigger thermodynamics picture. In later topics, you may see that entropy and Gibbs free energy help explain why some heat-absorbing processes still happen on their own.
Keep studying Intro to Chemistry Unit 5
Visual cheatsheet
view galleryExothermic Process
This is the opposite energy flow. Exothermic processes release heat to the surroundings, so the surroundings warm up and is negative. Comparing the two helps you read reaction profiles and spot which side has the higher enthalpy in a problem or energy diagram.
$\Delta H$ (Enthalpy Change)
Endothermic processes have a positive , which means the system absorbs heat overall. If you are given a thermochemical equation, the sign of tells you whether energy is entering or leaving the system. That sign is one of the fastest ways to classify the process.
$\Delta H_{soln}$
Some dissolving processes are endothermic, and tracks the heat change when a substance dissolves. If the solution gets colder, the dissolution is absorbing heat from the water and container. That is why solution temperature changes are such a useful lab clue.
Specific Heat Capacity
Specific heat capacity tells you how much heat a substance needs for its temperature to change. In an endothermic process, the heat absorbed comes from the surroundings, which can lower their temperature depending on their mass and specific heat. This is why the same reaction can feel colder in one setup than another.
A quiz or problem set will usually ask you to identify whether a reaction or change is endothermic from a description, an energy diagram, or a temperature change. You might see a word problem where a solution gets colder after a salt dissolves, and you need to decide whether heat moved into the system or out of it.
You may also have to label products and reactants on a diagram, or state the sign of . If the process absorbs heat, the answer should match that energy flow, not just the word "cold" by itself. A cold container usually means the surroundings lost heat to the system, so trace the direction carefully before answering.
These two get mixed up because both involve heat transfer, but the direction is opposite. Endothermic means the system absorbs heat from the surroundings and is positive. Exothermic means the system gives off heat to the surroundings and is negative.
An endothermic process absorbs heat from its surroundings, so the surroundings usually cool down.
In Intro to Chemistry, endothermic behavior shows up in phase changes, dissolving, reactions, and energy diagrams.
For an endothermic reaction, is positive because the products end up at higher enthalpy than the reactants.
A process can be endothermic without being impossible, because heat flow is only one part of the full thermodynamics picture.
If a substance dissolving in water makes the solution colder, that is a strong clue the dissolution is endothermic.
It is a chemical reaction or physical change that absorbs heat from the surroundings. That heat goes into the system, so the surroundings usually drop in temperature. In chemistry class, you will see this in phase changes, dissolving, and reaction energy diagrams.
Look for heat flowing into the system. If the surroundings get cooler, if the process needs energy input to keep going, or if the energy diagram shows products above reactants, those are all endothermic clues. A positive also points to an endothermic process.
Melting ice is endothermic because the ice absorbs heat from its surroundings to break out of the solid lattice and become liquid water. That is why ice feels cold and why the air or your hand near it can lose heat.
Endothermic processes absorb heat, so the system takes energy in and the surroundings cool down. Exothermic processes release heat, so the system gives energy off and the surroundings warm up. The sign of flips too, positive for endothermic and negative for exothermic.