STAAR Review – Day 3
Chemical Reactions
Equations
Law of Conservation of Mass
Law of Conservation of Mass
• States: No new matter is created or destroyed
– it is just rearranged (chemically).
• OR
• The mass of the substances in the reactants is
equal to the mass of the substances in the
products.
Chemical Reactions
• Chemical Reactions – substances are changed to
entirely new substances.
• City Girls (Guys) Love Their Phones (evidence of a
chemical reaction):
• Color change
• Gas Production (bubbling)
• Light Production
• Temperature Change (gets hot or cold)
• Precipitate formation (small particles form)
Chemical Reactions
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Other forms of evidence are:
Oxidation (rusting)
Tarnishing
Endothermic Reactions (energy is absorbed)
Ex of Endothermic – cake baking in the oven
Exothermic Reactions (energy is released)
Ex of Exothermic – an explosion (light and
heat energy released)
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Equations
1)____ N2 + ____ H2
____ NH3
2) ____ KClO3
____ KCl + ____ O2
3) ___ NaCl + ___ F2
___ NaF + ___ Cl2
4) ____ H2 + ____ O2
____ H2O
Left side is the
reactants.
The arrow is
the yield
sign
Right side is the
products
Balanced Equation