http://www.ck12.org Chapter 3. Chemical Interactions
Parts of a Solution
All solutions have two parts: the solute and the solvent. The solute is the substance that dissolves, and the solvent
is the substance that dissolves the solute. Particles of solvent pull apart particles of solute, and the solute particles
spread throughout the solvent. Salt water, such as the ocean water in theFigure3.86, is an example of a solution.
In a saltwater solution, salt is the solute and water is the solvent.
FIGURE 3.86
Q:A scientist obtained a sample of water from the Atlantic Ocean and determined that the sample was about 3.5
percent dissolved salt. Predict the percent of dissolved salt in a sample of water from the Pacific Ocean.
A:As a solution, ocean water is a homogeneous mixture. Therefore, no matter where the water sample is obtained,
its composition will be about 3.5 percent dissolved salt.
Soluble or Insoluble?
Not only salt, but many other solutes can dissolve in water. In fact, so many solutes can dissolve in water that water
has been called the universal solvent. Even rocks can dissolve in water, which explains the cave that opened this
article. A solute that can dissolve in a given solvent, such as water, is said to besolublein that solvent. Conversely,
a solute that cannot dissolve in a given solvent is said to beinsolublein that solvent.
Although most solutes can dissolve in water, some solutes are insoluble in water. Oil is an example. Did you ever
try to mix oil with water? No matter how well you mix the oil into the water, after the mixture stands for a while,
the oil separates from the water and rises to the top. You can see how oil floats on ocean water in theFigure3.87.
Solutions and States of Matter
Like salt water in the ocean, many solutions are normally in the liquid state. However, matter in any state can form
a solution. An alloy, which is a mixture of a metal with one or more other substances, is a solid solution at room
temperature. For example, the alloy bronze is a solution of copper and tin. Matter in the gaseous state can also form
solutions.
Q:What is an example of a gaseous solution?
A:Air in the atmosphere is a gaseous solution. It is a mixture that contains mainly nitrogen and oxygen gases,
with very small amounts of several other gases. The circle graph in theFigure3.88 shows the composition of air.