what are the differences between evaporation and boiling?

Question

i'm doing organic chemistry at university level, and i've been assigned the task of stating the deferences between the two. i'd greatly appreciate help on this matter.

Answer 1

Boiling is very rapid evaporation starting at the bottom of a container of water.

Evaporation occurs fastest where there is the most heat (energy). When we heat water to
make it boil we heat it from the bottom so the evaporation occurs at the bottom of the
pot. As a result, large bubbles of water vapor form at the bottom and rise to the
surface in the boiling action. If we applied the same heat to the top surface of the
water it would evaporate just as quickly but we would not call it boiling because the
bubbles would not form and rise to the surface.

Normally evaporation occurs at a much slower rate than boiling because most evaporation
occurs with room temperature water.

Evaporation-is the escape of molecules from the liquid state to the gas or vapor state.
In evaporation, molecules of higher-than-average kinetic energy escape from a liquid,
leaving it cooler than it was before they escaped.

Boiling-is the temperature at which the vapor pressure of a liquid is equal to the
external pressure above the liquid. When we give the boiling point of a liquid, we
need also to state the pressure.

Answer 2

At first glance, it would seem that evaporation and boiling might be the same process, because both start with a liquid and end up with a gas. However, there are some important macroscopic and microscopic differences that help make the distinction.

Evaporation happens only at the surface of a liquid and occurs at any temperature (so long as the substance is a liquid at that temperature). However, as most people are aware, liquids evaporates faster at a higher temperature.

Boiling, on the other hand, happens throughout the bulk of a liquid, usually starting from some site on the inside of the container and rising in a bubble to the surface. It only happens when the temperature is above the boiling point of that substance.

Boiling occurs when the average motion of particles is fast enough to overcome the forces holding them close together. This happens evenly throughout a boiling liquid because the temperature is uniform throughout.

Evaporation happens for the following two reasons:

Not all particles in the liquid are moving at the same speed and, as a result, the faster particles are more likely to overcome the forces they feel from their neighbors.
The particles at the surface of the liquid are only held in place by forces from the neighboring particles beneath them, whereas particles in the middle of the liquid have forces holding them on all sides. Thus, particles at the surface find it easier to break away from the liquid.
In the cases of both boiling and evaporation, the force between two particles is always present. The greater the space between the particles becomes, however, the weaker the force is between them. To break the bond between two particles, one particle has to be moving fast enough to overcome the pull of the other, until it gets so far away that pull is diminished. An analogy would be if you tried to jump off the Earth: we cannot jump fast enough to get to where Earth's gravity has less pull, but a rocket can.

Answer 3

Boiling is of course just steam escaping from the liquid state and is the same process as evaporation. The only difference would be the nature of the heating process driving the escape. Boiling implies and active heat source while evaporation usually is passive although again the distinction is somewhat nebulous. Everything comes down to definition and you are left with common conventions like boiling water on the stove is the normal convention while clothes drying on the line is conventionally thought of as evaporation. Go for extra points and mention sublimation!

Answer 4

Evaporation is the process whereby atoms or molecules in a liquid state gain sufficient energy to enter the gaseous state (the equivalent process in solids is known as sublimation). It is the opposite process of condensation. Evaporation is exclusively a surface phenomena and should not be confused with boiling. Most notably, for a liquid to boil, its vapor pressure must equal the ambient pressure, whereas for evaporation to occur, this is not the case.

Answer 5

Evaporation is the liquid turning into a gas as the surface molecules acquire energy from the environment. Boiling is when the whole body if liquid has so much energy that some of the liquid has to turn into gas in order for the rest to remain liquid.

Answer 6

Evaporation is when water passes from liquid state to gas state and boiling is when the water has reached the specific heat previous to evaporation. You know that water boils at temperature of 100°C equivalent to 212°F.

Answer 7

'Evaporation' and 'Vaporisation' technically mean the same but, they are named differently due to the following reasons: -

The boiling point of a liquid is the temperature at which its vapour pressure is equal to the pressure of the surrounding air (or gas).
The normal boiling point of a liquid is the temperature at which its vapor pressure is equal to atmospheric pressure.
Boiling produces a vapour and, as heat is continued to be added to the liquid, the liquid is "VAPORISING".
(Higher or lower pressure acting on the liquid will increase or decrease the boiling temperature accordingly).
Boiling is the temperature at which a liquid vaporises and its vapour pressure is very slightly higher than atmospheric.

When, for example, the vapour pressure of a liquid is equal to the surrounding pressure, they are said to be "In Equilibrium" and the liquid is at its boiling temperature.
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At any temperature below the boiling point, substances exert a vapour pressure due to some molecules 'jumping out' of the liquid into the space above it (called vapour space).
The movement of air over the liquid, drives this vapour away and the liquid dissipates into the atmosphere.

A pool of rainwater left on the ground after the rain stops, as you may have noticed, gradually disappears. If its breezy, it disappears faster. This is 'EVAPORATION' and, as stated, can take place at any temperature below its normal boiling point.

Answer 8

Evaporation - vapour lost from the surface at all temperatures below the boiling point.
Boiling - vapour formed throughout the liquid, with consequent bubbles, because the vapour pressure now equals atmospheric pressure.

Answer 9

Evaporation is to change from a liquid or solid state into vapor; pass off in vapor. Boiling is the change from liquid to a gaseous state, producing bubbles of gas that rise to the surface of the liquid, agitating it as they rise.

Answer 10

if u ask me, boiling is the process where the chemicals gets heat up...while evaporation is the process where chemicals transform into gas from its liquid state...these are just simple terms...if you need those very scientific terms...ask your book...or research about it....