Solutes and Solvents:
What did the green tea say to the hot water? I solute you!
Have you ever made ice tea? Often you can do so by mixing a powder with water. Did you
use more water, or more powder?
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Most likely, you used a lot of water, and a small amount of powder.
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What kind of mixture is iced tea?
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It looks like a pure substance, but you know that it contains at least 2 components (water
and tea)
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The part that is present in the larger quantity is called the solvent
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The solute is present in smaller quantities
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The solute s are the parts of a solution that dissolve; solutions
are generally made by dissolving one or more solutes in a solvent
Liquid Solutions
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You are probably familiar with a variety of liquid solutions. These all have a liquid
solvent. Lets create a list of liquid solutions:
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In food preparation, the solvents are usually liquids like water, vegetable oil, or an
alcohol (like vanilla extract)
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In ice tea, water is the solvent
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Water is the most common solvent on Earth
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Although water is the most common solvent on Earth, it doesn’t dissolve everything:
other solvents are needed for specific things:
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Ethanol is used as a solvent for perfumes
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Turpentine is used as a solvent for paints
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Ethyl acetate is one of the solvents used in nail polish
Liquid Solutions cont…
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Solutes that dissolve in liquids may be solid, liquids or gases.
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Salt and sugar are common solid solutes
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Acetic acid is a liquid solute added to water, to form vinegar
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Gases like carbon dioxide and nitrogen dissolve in our blood and are carried
around our bodies
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What other solids, liquids and gases (solutes) act as solutes that dissolve
in liquids
Water: The Universal Solvent
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Tap water generally looks and tastes like pure water, yet it is a solution that contains
many, many solutes. These include:
Iron
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Aluminum
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Fluorine
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Calcium
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Salt
How did they get into your tap water.
Magnesium
Chlorine
Water: The Universal Solvent cont…
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As water flows in rivers and lakes and underground, it comes into contact with soil,
gases and minerals (eg. Gases from the air and minerals from the rock and soil dissolve
in water)
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Pollutants may also dissolve in the water
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Before reaching your tap, it is cleaned to make it safe for drinking; chlorine and
fluorine are sometimes added to the water
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Chlorine kills bacteria and fluorine may help keep your teeth healthy
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Water probably dissolves more different substances than any
other solvent
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For this reason, WATER is the Universal Solvent
Water is the Universal Solvent
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Water is important to every living thing on earth. Being the Universal Solvent
means that wherever water goes, either through the ground or through our
bodies, it takes along valuable chemicals, minerals, and nutrients.
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It is water's chemical composition and physical attributes that make it such an
excellent solvent. Water molecules have a polar arrangement of the oxygen
and hydrogen atoms—one side (hydrogen) has a positive electrical charge and
the other side (oxygen) had a negative charge. This allows the water
molecule to become attracted to many other different types of molecules.
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Water can become so heavily attracted to a different molecule, like salt
(NaCl), that it can disrupt the attractive forces that hold the sodium and
chloride in the salt molecule together and, thus, dissolve it.
Source: http://water.usgs.gov/edu/qa-solvent.html
Solid Solutions
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Not all solutions are liquids. In a solid solution, both the solvent and the solute
are solid. The gold used to make jewellery is often called 14-karat gold.
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Pure gold is actually 24-karat, so 14-karat gold is made up of 14 parts gold to 10 parts
of other metals – generally copper, silver, nickel or palladium
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Gold is the solvent and the other metals are the solutes
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Solid solutions are called alloys when they contain two or more metals: to make alloys,
metals are heated until they melt, and then they are mixed together, and allowed to
cool.
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Brass is an alloy of copper and zinc; bronze is an alloy of copper and tin
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With both brass and bronze, copper is the solvent. What are the solutes.
Gas Solutions
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The air you breathe is 71% nitrogen gas, 21% oxygen gas and 1% argon gas,
along with smaller amounts of other gases like carbon dioxide.
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Air is, therefore, a solution that is also a gas.
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What is the solvent for the air we breathe. What are the solutes.
Water Pollution
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Plants and animals get some of the nutrients they need from water.
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Unfortunately, because water is such a good solvent, it can also dissolve
pollutants, too.
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Pollution includes any pure substance or mixture that contaminates the
natural environment
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Polluted water is a mixture of pure water and pollutants
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It is crucial to keep water in our lakes, rivers and oceans clean, so that
organisms can grow and live there normally