SNC2D
Conservation of Mass
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Conservation of Mass
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atomic theory states that matter is neither created, nor destroyed
significant contributions were made by Antoine Lavoisier who, together with his wife Marie-Anne,
conducted hundreds of experiments on chemical reactions
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their work is summarized in the Law of Conservation of Mass which states that
In a chemical reaction, the total mass of the products
is always the same as the total mass of the reactants
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therefore, in a chemical reaction, the atoms are simply rearranged
chemical reactions are shown using chemical equations
the general form is shown below
REACTANTS
PRODUCTS
Left Side
Starting Substances
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Right Side
Ending Substances
there are 3 types of chemical equations:
1.
Word Equations
e.g.,
hydrogen
+
describe the chemical reaction in words
oxygen
water
“hydrogen reacts with oxygen to produce water”
2.
Skeletal Equations
e.g.,
3.
e.g.,
H2
+
words are replaced with chemical formulas
O2
H2 O
Balanced Chemical Equation follows the Law of Conservation of Mass
– type and number of atoms on reactant side
equals that on the product side
2
H2
+
O2
2
H2 O
Coefficients are used to show how many molecules are reacting
NOTE:
you must never change the subscripts
– this changes the chemical formula for a substance
Additional Information
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often the letters s, l, g are added to the compounds to show the state of matter
(i.e., (s) is a solid; (l) is a liquid; and (g) is a gas)
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(aq) refers to aqueous solution – something dissolved in water