# What happens to matter when it boils?

## What happens to matter when it boils?

As the temperature of a liquid is increased, the particles gain more energy and move faster and faster. At this point, the liquid is becoming a gas (also called a vapor). The temperature at which this happens depends on what the substance is.

## When water boils does it lose or gain energy?

As an example, if you boil water, it never goes above 100 degrees Celsius. Only after it has completely evaporated will it get any hotter. This is because once water reaches the boiling point, extra energy is used to change the state of matter and increase the potential energy instead of the kinetic energy.

How do water boils?

How Does boiling Occur? When atoms or molecules of a liquid are able to spread out enough to change from a liquid phase to a gaseous phase, bubbles form and boiling occurs. Figure 1: Formation of bubbles in boiling water.

How does water look when it’s boiling?

Look at the water. If large bubbles are rising from the bottom of the pot to the surface, the water is boiling. NOTE: Small bubbles that stay at the bottom or sides of the pot are air bubbles present in the water; they do not necessarily indicate that boiling is imminent.

### How do you describe the movement of water once it boils?

When boiling occurs, the more energetic molecules change to a gas, spread out, and form bubbles. These rise to the surface and enter the atmosphere. It requires energy to change from a liquid to a gas (see enthalpy of vaporization). In addition, gas molecules leaving the liquid remove thermal energy from the liquid.

### When water boils you see this coming out of the vessel?

These bubbles are water vapor. When you see water at a “rolling boil,” the bubbles are entirely water vapor. Water vapor bubbles start to form on nucleation sites, which are often tiny air bubbles, so as water starts to boil, the bubbles consist of a mixture of air and water vapor.

How do you show water molecules moving at different temperatures?

Show an animation of water molecules at different temperatures. Move the slider at the bottom of the window all the way to the right to show that the water molecules are moving faster and are a little farther apart in hot water. Explain that the little balls represent the particles of a liquid, in this case water molecules.

Why are water molecules closer together in cold water?

The water molecules are closer together because the slower motion allows the attractions to bring the molecules a little closer together. Would there be more or fewer motion lines? Students should realize that since the molecules in the cold water are moving slower, they should have fewer motion lines than the molecules in room-temperature water.

#### What happens to the volume of water when it is heated?

You heat the water to 100 °C and notice that the volume increases to 104 milliliters. Using what you know about the attractions between water molecules and the way heating affects molecular motion, explain why the volume of water in the cylinder increases when it is heated.

#### What happens to the speed of molecules when heated or cooled?

Heating a liquid increases the speed of the molecules. An increase in the speed of the molecules competes with the attraction between molecules and causes molecules to move a little further apart. Cooling a liquid decreases the speed of the molecules.