Classes of Matter Mixtures and Solutions

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Classes of MatterMixtures and Solutions
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Vocabulary

• Homogeneous Matter
• Heterogeneous Matter
• Solute
• Solvent
• Aqueous Solution
• Tincture Solution
• Colloid
• Homogeneous Mixture

• Heterogeneous Mixture
• Concentrated Solution
• Unsaturated Solution
• Supersaturated Solution
• Dilute Solution
• Saturated Solution
• Alloy

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Classes of Matter

• Matter exists as
• Elements simplest type of pure substance
• Compounds two or more elements chemically
  combined
• Mixtures matter that consists of two or more
  substances mixed together but not chemically
  combined
• Solutions homogeneous mixture in which one
  substance is dissolved in another

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Classes of Matter contd

• Homogeneous matter All parts of the homogeneous
  matter are alike. The properties of any one part
  of the matter are identical to the properties of
  all the other parts (sugar, salt, water, and
  whipped cream are examples).
• Heterogeneous matter The properties of any one
  part of the matter are different from the
  properties of all the other parts (soil, a
  cheeseburger and raisin bran cereal are all
  examples).

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Review Questions

• According to makeup, what are the four classes of
  matter?
• What is homogeneous matter? Heterogeneous
  matter?
• Classify the following materials as either
  homogeneous or heterogeneous sausage pizza
  chocolate chip cookie air inside a balloon
  glass of water.

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Properties of Mixtures

• Substances in a mixture are not chemically
  combined, they keep their separate identies and
  most of their own properties.
• Substances in a mixture may change in physical
  appearance when they dissolve (dissolving sugar
  in water is an example, the same sugar and water
  particles are present and no new substance is
  formed)

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Properties of Mixtures contd

• The substances in a mixture can be present in any
  amount
• The substances in a mixture retain their original
  properties and can be separated out by simple
  physical means (a mixture containing sulfur and
  iron can be separated using a magnet iron
  particles are attracted to the magnet, sulfur is
  not).
• Critical Thinking Question What are some other
  physical properties of matter that might be used
  to separate mixtures?

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Types of Mixtures

• Heterogeneous Mixture A mixture that does not
  appear to be the same throughout.
• Suspension A heterogeneous mixture of larger
  particles that are visible and will settle out on
  standing (ex. Italian dressing, sand and water).
• Homogeneous Mixture A mixture that appears to
  be the same throughout. The particles of the
  mixture are very small, not easily recognized,
  and do not settle when the mixture is allowed to
  stand.
• Solution a type of homogeneous mixture formed
  when one substance dissolves in another.

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The answer to these questions is the same The
sugar and gaseous carbon dioxide both dissolve in
the substances in which they are mixed.

• What happens when a lump of sugar is dropped into
  a glass of lemonade?
• What takes place when carbon dioxide gas is
  bubbled through water?

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Homogeneous Solutions

• If you look at both of these mixtures (lemonade
  and soda water) you will not see molecules of
  sugar or carbon dioxide, but..
• Does the lemonade taste sweet?
• Is the soda water fizzy?
• The molecules of one substance have become evenly
  distributed among the molecules of the other
  substance.
• The molecules making up a solution are too small
  to be seen and do not settle when the solution is
  allowed to stand.

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Properties of Solutions

• Solute In a solution, the substance that is
  dissolved. (example salt being dissolved in
  water)
• Solvent The substance that does the dissolving.
  (in the salt water example, water is the
  solvent)
• Applying Concepts - In the sweetened lemonade
  example, which is the solute and which is the
  solvent?

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Properties of Solutions contd

• aqueous solution Solutions in which the solvent
  is water. (Water is the most common solvent)
• tincture A solution with alcohol as the
  solvent. (Alcohol is commonly mixed with iodine
  and used as a antiseptic for cuts and scratches)
• colloid A homogeneous mixture whose particles
  can be seen in the air (ex. dust in the air, fog,
  jello, mayonnaise, and whip cream)
• alloy A solution of two metals or a metal and a
  nonmetal that has the properties of a metal.

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Solubility

• The solubility of a solute is a measure of how
  much of that solute can be dissolved in a given
  amount of solvent under certain conditions.
  Table salt and sugar dissolve very easily in
  water and are described as very soluble.
• The main factor that affects the solubility of a
  solute is temperature. The solubility of most
  solids is increased by raising the temperature of
  the solution.

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More on Solubility

• The solubility of gas decreases as the
  temperature of the solution increases. Have you
  ever let a glass of soda get warm? If so, what
  did you notice? The soda goes flat or looses its
  fizz. Soda is given its fizz by dissolving
  carbon dioxide gas in soda water.

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Concentration of Solutions

• Concentrated Solution A solution in which a lot
  of solute is dissolved in a solvent. This term
  is not very precise because it does not indicate
  exactly how much solute and solvent are present.
• Dilute Solution A solution in which there is
  little solute dissolved in a solvent. This term
  is not very precise because it does not indicate
  exactly how much solute and solvent are present.

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More Concentration.

• Saturated Solution a solution that contains
  all the solute it can possibly hold at a given
  temperature. (NO more solute can be dissolved at
  that temperature) When describing a saturated
  solution the temperature must always be given.
• Unsaturated Solution a solution that contains
  less solute than it can possibly hold a a given
  temperature. (MORE solute could be dissolved at
  that temperature.
• Supersaturated Solution Under special
  conditions, a solution can be made to hold more
  solute than is normal for that temperature.
  Supersaturated solutions are made by allowing a
  saturated solution at a high temperature to cool
  gradually without disturbance.

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Review Questions

• What is a mixture? What are three properties of
  a mixture?
• How is a heterogeneous mixture different from a
  homogeneous mixture?
• What is a solution? What are its two parts?
• What is an aqueous solution? A tincture?

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Review Questions contd

• What is solubility? What factor affects the
  solubility of a solute?
• Compare a saturated, unsaturated, and
  supersaturated solution.
• Describe how you would separate salt from water
  in a saltwater mixture. What physical properties
  of the substances are you using to separate the
  mixture?