Solute and Solvent
Jean Brainard, Ph.D.
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Printed: June 30, 2013
AUTHOR
Jean Brainard, Ph.D.
www.ck12.org
C ONCEPT
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Concept 1. Solute and Solvent
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Solute and Solvent
Define solute and solvent.
Identify solutes and solvents in different states of matter.
Describe water as a solvent.
Explain how ionic and covalent solutes dissolve in water.
This giant Buddha statue, which is a national treasure in Japan, is made of bronze. Bronze consists mainly of copper
but also contains some tin. Bronze is an example of a solution. A solution is a type of mixture that has the same
composition throughout.
How a Solution Forms
A solution forms when one substance is dissolved by another. The substance that dissolves is called the solute. The
substance that dissolves it is called the solvent. The solute is present in a lesser amount that the solvent. When the
solute dissolves, it separates into individual particles, which spread throughout the solvent.
Q: In bronze, what are the solute and solvent?
A: Because bronze consists mainly of copper, copper is the solvent and tin is the solute. The two metals are combined
in a hot, molten state, but they form a solid solution at room temperature.
What’s Your State?
In the example of bronze, a solid (tin) is dissolved in another solid (copper). However, matter in any state can be the
solute or solvent in a solution. For example, in a saltwater solution, a solid (salt) is dissolved in a liquid (water). The
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Table 1.1 describes examples of solutions consisting of solutes and solvents in various states of matter. Yon learn
more about solutions such as these at this URL: http://www.youtube.com/watch?v=NsdBUWnG2cQ
TABLE 1.1: Solutes, Solvents, and States of Matter
Type of Solution: Example
Gas dissolved in gas: dry air
Gas dissolved in liquid: carbonated
water
Liquid dissolved in gas: moist air
Liquid dissolved in liquid: vinegar
Solid dissolved in liquid: sweet tea
Solute
oxygen
carbon dioxide
Solvent
nitrogen
water
water
acetic acid
sugar
air
water
tea
Water as a Solvent
Salt isn’t the only solute that dissolves in water. In fact, so many things dissolve in water that water is sometimes
called the universal solvent. Water is such a good solvent because it is a very polar compound. A polar compound
has positively and negatively charged ends. Solutes that are also charged are attracted to the oppositely charged ends
of water molecules. This allows the water molecules to pull the solute particles apart.
On the other hand, there are some substances that don’t dissolve in water. Did you ever try to clean a paintbrush
with water after painting with an oil-based paint? It doesn’t work. Oil-based paint is nonpolar, so its particles aren’t
charged. As a result, oil-based paint doesn’t dissolve in water. (You can see how to dissolve oil-based paint in the
Figure 1.1.)
Like Dissolves Like
These examples illustrate a general rule about solutes and solvents: like dissolves like. In other words, polar solvents
dissolve polar solutes, and nonpolar solvents dissolve nonpolar solutes. You can see a student’s video demonstrating
solutes that do and solutes that don’t dissolve in water at this URL: http://www.youtube.com/watch?v=ek6CVVJk4
OQ&feature=related
Ionic and Covalent Solutes
All solutes separate into individual particles when they dissolve, but the particles are different for ionic and covalent
compounds. Ionic solutes separate into individual ions. Covalent solutes separate into individual molecules.
Salt, or sodium chloride (NaCl), is an ionic compound. When it dissolves in water, it separates into positive sodium
ions (Na+ ) and negative chloride ions (Cl− ). You can see how this happens in the Figure 1.2. The negative oxygen
ends of water molecules attract the positive sodium ions, and the positive hydrogen ends of water molecules attract
the negative chloride ions. These forces of attraction pull the ions apart. You can watch this happening in animations
at these URLs: http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/thermochem/solutionSal
t.html http://www.youtube.com/watch?v=gN9euz9jzwc&feature=related
The sugar glucose is a covalent compound. When sugar dissolves in water, it forms individual glucose molecules
(C6 H12 O6 ). You can see how this happens in the Figure 1.3. Sugar is polar like water, so sugar molecules also have
positive and negative ends. Forces of attraction between oppositely charged ends of water and sugar molecules pull
individual sugar molecules away from the sugar crystal. Little by little, the sugar molecules are separated from the
crystal and surrounded by water. You can watch this happening in the video at the following URL: http://www.youtu
be.com/watch?v=hydUVGUbyvU
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Concept 1. Solute and Solvent
FIGURE 1.1
To dissolve a nonpolar solute such as oilbased paint, a nonpolar solvent such as
paint thinner must be used.
FIGURE 1.2
Summary
• A solution forms when one substance dissolves in another. The substance that dissolves is called the solute.
The substance that dissolves it is called the solvent.
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FIGURE 1.3
• Solutes and solvents may be any state of matter.
• Many solutes dissolve in water because water is a very polar compound.
• A general rule: like dissolves like. For example, polar solvents dissolve polar solutes, and nonpolar solvents
dissolve nonpolar solutes.
• Ionic solutes separate into individual ions when they dissolve. Covalent solutes separate into individual
molecules.
Vocabulary
• solute: Substance that dissolves in a solvent to form a solution.
• solvent: Substance that dissolves a solute to form a solution.
Practice
Watch the video about solutes and solvents at the following URL, and then answer the questions below. http://w
ww.youtube.com/watch?v=M5Tx99IN_K4
1. The majority component of a solution is the __________.
2. The minority component of a solution is the __________.
3. Decide whether the following statement is true or false, and then explain why: There is no such thing as a
universal solvent.
4. An aqueous solution is a solution in which the solvent is __________.
5. A solution in which there is a lot of solute relative to the solvent is __________.
6. A solution in which there is little solute relative to the solvent is __________.
7. How is the concentration of solute in a solution measured?
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Concept 1. Solute and Solvent
Review
1.
2.
3.
4.
Compare and contrast the solute and solvent of a solution.
Describe an example of a gaseous solute dissolved in a liquid solvent.
Explain the expression “like dissolves like,” and give an example.
Outline how sodium chloride dissolves in water.
References
1. CK-12 Foundation. . CC-BY-NC-SA 3.0
2. Christopher Auyeung/CK-12 Foundation. . CC-BY-NC-SA 3.0
3. Christopher Auyeung/CK-12 Foundation. . CC-BY-NC-SA 3.0
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