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ELEMENTS, COMPOUNDS
AND MIXTURES
Food Chemistry
OBJECTIVES Distinguish between pure substances and
mixtures. Compare homogeneous and heterogeneous
mixtures. Define solutions. Distinguish between a solute and solvent. Recognize water as a universal solvent. Understand the processes of solubility and
saturation.
OVERVIEWMatter Anything that has mass and takes up space.
Physical Properties A characteristic that can be observed or
measured without changing the substance Solid Liquid Gas
Chemical Properties The ability of a substance to react with other
substances
PHYSICAL PROPERTIES
CLASSIFICATIONS OF MATTER
www3.delta.edu
PURE SUBSTANCES Made of only one kind of material and
has definite properties
Elements Sodium, Carbon, Iron
Compounds Table salt, water, sugar
MIXTURES A combination of two or more
substances in which each substance keeps at least some of its original properties.
Physically blended, not chemically.
Homogeneous Mixtures
Heterogeneous Mixtures
Solutions Colloids
HOMOGENEOUS MIXTURES The same in every part of a given
sample.Examples: salt water, milk, air, cola
Another name for a homogeneous mixture:
Solution – one substance is dissolved in another
Solution
Solute Solvent
SOLUTE VS. SOLVENT
SOLUTE SOLVENT
The substance that is dissolved Sugar Salt
The substance that dissolves another substance Water
Water is recognized as a universal solvent.
This can be a problem with vitamins and minerals dissolving in cooking water.
HETEROGENEOUS MIXTURES Individual substances are dissimilar and
can be recognized by sight.This is also known as “Immiscible”Examples: salad, potato soup, Italian
dressing
SATURATED VS. UNSATURATED SOLUTIONSUnsaturated Solution: A solution that contains less solute than
can be dissolved in it at a given temperature.
Saturated Solution: A solution that contains all the solute
that can be dissolved at a given temperature.
SOLUBILITY The maximum amount of solute that can
dissolve in a given quantity of solvent at a specific temperature.
The solubility of most solids dissolved in a liquid increases as the temperature increases.
Example: Sugar dissolves faster in boiling water.
The solubility of gas decreases as the temperature increases.
Example: A warm can of soda will go flat faster than a cold can of soda.
SOLUTE & PHASE CHANGES The amount of solute in a solution
affects the temperature at which the solution boils or freezes.
The more solute present in a solution, the higher the boiling point and the lower the freezing point.
Example: Ice cream is still soft in the freezer because of the sugar dissolved in the water.
IDENTIFY THE MIXTURESYour table now has 4 glasses. Add 4 different
solutions to the glasses and identify the type of mixture as homogeneous or heterogeneous.
Glass # 1 – Place 1 drop of food coloring in your glass of water and stir.
Glass # 2 – Add ¼ cup oil to the water.Glass # 3 – Add ¼ cup vinegar the water.Glass # 4 – Add ¼ cup vinegar to the oil.
SOLUBILITY LAB Make Iced Tea using both cold and hot
water. Compare the flavors and answer the
questions to review the scientific theme of the week.