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Sublimation is an endothermic process. This means it requires energy to happen. During sublimation, a solid changes directly into a gas without becoming a liquid first. For this to occur, the solid must absorb heat energy from its surroundings.
This heat energy helps the particles in the solid move faster and break free from their fixed positions. As the solid gains enough energy, the bonds between its particles weaken, and the particles escape directly into the air as gas. Since energy is going into the substance, sublimation is endothermic.
A great example is dry ice, which is frozen carbon dioxide. When you place dry ice on a surface at room temperature, it doesn’t melt. Instead, it disappears into gas. This happens because the dry ice absorbs heat from the air around it. That heat gives the carbon dioxide molecules enough energy to break free from the solid and spread out as gas.
You can compare this to boiling water, which is also endothermic. Just like water needs heat to turn into steam, a solid needs heat to turn directly into gas during sublimation.
Fun Fact: If you touch dry ice, it can burn your skin! That’s because it absorbs heat so quickly from your skin during sublimation.
What kind of process is sublimation?
ExothermicNeutralEndothermicMechanicalWhat does "endothermic" mean?
Gives off energyRequires energy to happenHappens without energyFreezes a substanceWhy is heat needed during sublimation?
To make the substance colderTo melt the substance into a liquidTo help particles stay in placeTo break bonds and allow particles to become gasWhat is an example of a substance that undergoes sublimation?
SteamWaterDry iceOxygen gasWhat happens to the particles in a solid during sublimation?
They slow down and freezeThey remain tightly packedThey melt and refreezeThey gain energy and spread outWhat makes sublimation similar to boiling?
Both happen without energyBoth release energy into the airBoth require heat to change statesBoth involve freezingIf a substance is absorbing heat and turning into gas, what type of reaction is occurring?
EndothermicExothermicCoolingExplosiveWhy can dry ice "burn" your skin?
It gives off heat quicklyIt freezes your skin solidIt absorbs heat from your skin rapidlyIt melts into hot liquid
