Give reasons for the following observation: the smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.

Asked on by sahiti13

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sciencesolve's profile pic

sciencesolve | Teacher | (Level 3) Educator Emeritus

Posted on

This happens because the average velocity of gas molecules depends on the temperature.

The equation that gives the velocity of gas molecules explains quite well how the temeparture and velocity of molecules relate such that:

`v = sqrt((2kT)/m)`

k expresses the Boltzman's constant

T represents the temperature

m expresses the molecular mass

Notice that the velocity of gas molecules is proportional to temperaure, hence, the velocity increases if the temperature raises.

Hence, since the smell of food is a gas, the hotter the food is, the faster the smell reaches you and the colder the food is, the slower the velocity of aroma molecules is.

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user4626090 | eNotes Newbie

Posted on

The molecules expand and spread far apart when heated, which is diffusion of gases in air due to the constant motion of gas particles

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