Melting (fusion)

[105691548]

Why is melting considered an endothermic reaction in the lecture because isn't it releasing heat when the substance is going from a solid to a liquid?

[Jennifer Huynh 3I]

An endothermic reaction is one that requires heat. Melting requires heat to break bonds between molecules. For example, to turn solid ice water into liquid water, heat is added to the system to break hydrogen bonds between water molecules. The heating curve of water shows that despite heat being added during the phase transitions, the temperature of the water does not change because the heat is used to break hydrogen bonds.

[Abby Citro 2A]

Fusion requires heat, and an endothermic reaction is one that requires heat. Melting requires heat because it needs to break the bonds between molecules, thus making it an endothermic reaction!

[605721741]

i like to think of it in real world applications. for ice cream to melt (go from solid to liquid), heat must be added. therefore, melting is endothermic.

[Diya Kar]

Melting is considered an endothermic reaction because for this to occur, the phase change of conversion from solid to liquid must occur. In order for this change in state of matter, heat/energy must be expended and inputted into the solid to allow it to melt into liquid. The absorption of energy is known as an endothermic reaction.

[KPINTO 1B]

The reason why melting is considered an endothermic reaction is because you are going from a solid to a liquid which means you are breaking bonds and you need energy to break these bonds to achieve the phase change or change in potential energy. By doing this, we know the change in enthalpy is going to be positive, so once again this furthers why melting is considered an exothermic process.

[805401611]

Melting is an endothermic reaction as the solid that is melting is taking heat energy from its surrounding in order to change its state from solid to liquid. With that, we are breaking bonds and that requires energy. And since we know that endothermic reactions require heat, we can define melting as an endothermic reaction as a result. Hope that helps!

[Eric Sun 2G]

An endothermic reaction requires heat to break the intermolecular forces or bonds between molecules. For instance, to undergo a phase change and turn solid ice into liquid water, it is necessary to add heat to break hydrogen bonds (intermolecular forces) between water molecules.

[Sara Dolmo 2J]

Because an endothermic reaction means that energy is required to break bonds, melting(fusion) is a great example of that. As things melt, the heat will break molecules and the atoms will move around faster and farther apart.

[Fiona H 2E]

Melting ice is an endothermic reaction because the ice absorbs (heat) energy, which causes a change to occur. This can also be shown on the heating curve for water.

[RobinFong_2B]

It is endothermic because a substance in a liquid state has more energy than its solid-state. The reaction requires energy(in the form of heat) in order to break its bonds. As a result, liquids are at a higher energy level and the net change in enthalpy is negative when you transition from a solid to a liquid.

[Ashley Wilson 2L]

Melting, or fusion, is an endothermic process because overcoming intermolecular forces requires energy. For example, it requires an input of energy to weaken the attraction between solid water and allow the water molecules to move freely as a liquid.

[Emily Wu 2G]

endothermic, because a substance in its solid state has more energy than it in its liquid state.

[Arjun_Anumula_3E]

Since the final product (liquid) has more energy than the reactants (solid), energy must have been added into the system. Hence, it is exothermic. However, I was kinda confused why the Delta H fus representing melting, because doesn't fusion mean bringing particles together??

[605499821]

I believe is the requirement of heat that makes it endothermic. For example, some ice absorbs heat energy to become a liquid.

[danielle05]

An endothermic reaction requires heat to break bonds between molecules, which is what happens when a substance melts. For example, leaving an ice cube outside on a sunny day would lead to the ice melting into water because the ice cube is taking in energy from the sun's heat. As a result, bonds break and atoms move faster, leading to the ice melting into water.

[Muryam_Hasan_2I]

You have to add heat to melt something, meaning that it is endothermic. If you hold an ice cube in your hand, the heat from your hand and the surrounding environment will cause it to melt. If this melting were to release heat, as you mentioned in your question, your hand would be warm because of the heat released—but, in this example, your hand is probably going to become pretty cold. This is because, instead of releasing heat, the melting ice absorbs heat.

[isabella garcia - 1G]

For a solid to undergo a phase change and become a liquid, heat needs to be applied and absorbed by the solid to break the intermolecular bonds between the molecules.

[Arshaun Faraji 2H]

to put it simply, fusion requires heat and so does an endothermic reaction.

[Lesley Kim 1K]

Melting would be considered an endothermic reaction because it requires heat (energy) in order for the process to take place. Think of ice cream. Ice cream melts because the surroundings are warm. That heat from the surroundings is absorbed by the ice cream which causes it to melt.

[elletruchan2I]

Melting is considered an endothermic reaction because the system needs to take in energy in order to break the lattice structure of the solid in order to turn into a liquid.

[Divya Mehta 2K]

Endothermic reactions require heat, so fusion would be such. In order to break the strong bonds between molecules, a high amount of heat and energy is required, making it an endothermic reaction!

[Veronica Larson- 1I]

Adding onto other comments, intuitively it should make sense that this is an endothermic reaction because you have to add heat in order to turn ice (solid) into water (liquid). This means it has to be absorbing heat, which would make it an endothermic reaction. Breaking the bonds in the solid to turn it into a liquid requires heat.

[Grant_2A]

An endothermic reaction is one that requires heat to take place, and melting requires heat to break the bonds so the system takes in energy, therefore making it endothermic.

[Mahli Martinez 2I]

For a reaction, to be endothermic, that means that it requires heat to actually take place. For something to melt, heat must be applied to break the bonds and convert a solid to a liquid.

[Jordyn Lee 1J]

Melting is considered an endothermic reaction because it requires an input of heat in order for a solid to melt into a liquid. For example, to heat solid butter into liquid, you need to heat it up in the microwave.

[Hannah Carsey 1B]

In order to melt a substance, heat energy is required, so the process is endothermic. Energy (in this case heat) is required to break bonds in order to cause a substance to go from a solid to a liquid (to melt the substance) so melting is endothermic. In an endothermic reaction, the products are higher in energy than the reactants. Therefore, the change in enthalpy is positive, and heat is absorbed from the surroundings by the reaction.

[405490807]

Melting is an endothermic process because it requires an intake of heat in order for the process to occur