Why Does Stretching A Rubber Band Make It Hot Entropy? (Question)

When molecules, not just rubber molecules, but any molecules, form crystals, they give off heat. This is why the rubber band feels hot when its stretched. When you let go of the rubber band, the polymer molecules break out of those crystals. Whenever molecules break out of crystals, they absorb heat.

What happens to entropy when you stretch a rubberband?

  • It seems that on stretching a rubberband, entropy or the degree of disorder is likely to increase. Is this the correct answer? My text says that on stretching, the arrangement of particles become more ‘ordered’ and hence entropy ‘decreases’.

What happens to entropy when a rubber band is stretched?

When stretched the polymer strands should be more aligned and straighten out along the direction of the stretching. When you relax it the strands go in all directions, or become more disordered. For this change the entropy increases, which means the heat is positive.

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Does entropy increase when a rubber band is stretched?

The cooling effect means that it is an endothermic process (D H>0) so that TD S is positive. Thus the entropy of the rubber band increases when it goes from the stretched state to the natural state.

Does a rubber band heat up or cool down when stretched?

As mentioned above, rubber bands tend to give off heat when they are stretched, and feel cool to the touch when they’re allowed to return to a “normal” state. While many people associate heat release with an energy change, there is no specific difference in the energy of a normal rubber hand and a stretched one.

Why does a rubber band contract when heated?

When the long chains get hotter and vibrate, they actually shorten, causing the material to contract. When the chains cool down, they relax and stretch out, causing the material to expand. The same thing happens when the polymer chains in rubber heat up and vibrate—they actually get shorter.

What happens when rubber is stretched?

A rubber band is an elastic material in nature. When stretched, it changes its shape and when the applied force is removed, it regains its original shape. That is why a rubber band changes its shape even though it is a solid. Also, if excessive force is applied then the rubber band would break.

Why does a rubber band resist stretching?

Rubber is made of molecules shaped like strands of spaghetti. If you stretch a rubber band, you pull those spaghetti-shaped molecules into a more or less straight line. But the molecules are still moving around. That motion causes the molecules to resist straightening.

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Why is the stretching of a rubber band a reversible change?

Explanation: If we stretch a rubber band with force of our hands, it undergoes a change and its length increases. But, on releasing the force, the rubber band comes back to its original length. So, the stretching of rubber band is a reversible change, the stretching of a spring is also a reversible change.

Why rubber band is stretched how it is connected to the elastic rebound theory?

This is what happens in a rubber band. As you stretch a rubber band, the material stores elastic energy, and its desire to snap back is the stored elastic energy. Once there is a lot of elastic energy stored, you can let it go.

Does rubber expand when heated?

Polymers like rubber shrink on heating as their molecular chains curl up, and water shrinks when warmed from its freezing point to around 4°C. After that, though, it behaves normally, and expands on warming. In contrast, so-called negative thermal expansion (NTE) materials never behave themselves.

Does rubber absorb heat?

These materials are called conductors. Then there are materials called “insulators” that do not allow energy to pass through easily. These materials include plastic, cork, wood, Styrofoam, and rubber. Thermal insulators are thus good at maintaining a consistent level of heat — whether hot or cold.

Is stretching a rubber band endothermic or exothermic?

A stretched rubber band feels warm against your lip, meaning that heat is released for stretching. Stretching is an exothermic process, so AH < 0.

Do rubber bands melt in boiling water?

Here’s the rub: the problem with rubber bands is that they are not designed to withstand the temperature of boiling water. “Since the boiling point of water is 212 F, there could possibly be some deterioration of the rubber.”

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How does temperature affect flexibility?

Logically, since ligaments and tendons are elastic structures, they should be more flexible with heat. Increasing temperature increases flexibility of knee ligaments (anterior and posterior cruciate) and there is a substantial change in tissue elasticity.

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