solutions

what is a solution

A solution is a mixture of two or more substances, but its not just any mixture. A solution is a homogeneous mixture. In a homogeneous mixture, the dissolved particles are spread evenly through the mixture. The particles of the solution are also too small to be seen or to settle out of the mixture. Click image to the left or use the URL below. URL:

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 the Figure 1.1, is an example of a solution. In a saltwater solution, salt is the solute and water is the solvent. 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.

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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 be soluble in that solvent. Conversely, a solute that cannot dissolve in a given solvent is said to be insoluble in 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 the Figure 1.2.

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 the Figure 1.3 shows the composition of air. Oil from an oil spill floats on ocean water. Because air is a solution, it is homogeneous. In other words, no matter where you go, the air always contains the same proportion of gases that are shown in the graph.

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instructional diagrams

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questions

a solution is any mixture of two or more substances.

a. true

-->  b. false

dissolved particles in a solution

-->  a) are too small to be seen.

b) will settle out of the solution.

c) will rise to the top of the solution.

d) two of the above

only liquids can form solutions.

a. true

-->  b. false

examples of solutions include

a) air.

b) salt water.

c) bronze.

-->  d) all of the above

which of the following substances is insoluble in water?

a) limestone

b) vinegar

-->  c) oil

d) two of the above

diagram questions

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