http://www.ck12.org Chapter 2. Matter
2.13 Liquids
- Identify properties of matter in the liquid state.
- Describe surface tension and viscosity of liquids.
Colored by lights at night, an incredible amount of water plunges continuously over the sheer rock wall of Niagara
Falls. If you stand close to the falls, the roar of the water is almost deafening, and the rushing water drenches you
with spray. No wonder Niagara Falls was once named one of the seven natural wonders of the world! It’s amazing
how such a common substance—water—can be so impressive.
Water and Other Liquids
Water is the most common substance on Earth, and most of it exists in the liquid state. Aliquidis one of four
well-known states of matter, along with solid, gas, and plasma states. The particles of liquids are in close contact
with each other but not as tightly packed as the particles in solids. The particles can slip past one another and take
the shape of their container. However, they cannot pull apart and spread out to take the volume of their container, as
particles of a gas can. If the volume of a liquid is less than the volume of its container, the top surface of the liquid
will be exposed to the air, like the vinegar in the bottle pictured in theFigure2.25.
Q:Why does most water on Earth’s surface exist in a liquid state? In what other states does water exist on Earth?
A:Almost 97 percent of water on Earth’s surface is found as liquid salt water in the oceans. The temperature over
most of Earth’s surface is above the freezing point (0°C) of water, so relatively little water exists as ice. Even near
the poles, most of the water in the oceans is above the freezing point. And in very few places on Earth’s surface do
temperatures reach the boiling point (100°C) of water. Although water exists in the atmosphere in a gaseous state,
water vapor makes up less than 1 percent of Earth’s total water.