Chemical Reactions. Homework Read pages: 61-63 Worksheet: Word Equations and Reactions 2.
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Transcript of Chemical Reactions. Homework Read pages: 61-63 Worksheet: Word Equations and Reactions 2.
Chemical Reactions
Homework Read pages: 61-63 Worksheet: Word Equations and Reactions
2
Describing Chemical Change
In a chemical reaction, one or more substances (reactants) change into one or more different substances (products).Reactants Products
Chemical reactions involve chemical changes.
Describing chemical changeReactants change into products
Bonds are broken Atoms re-arrange New bonds are formed
Atoms themselves are neither created nor destroyed!
Describing Chemical Change
What happens when you combine baking soda and vinegar ? describe some of the changes.
In aqueous solution, acetic acid reacts with sodium bicarbonate to produce sodium acetate, carbon dioxide and water.
Describing Chemical Change
sodium bicarbonate
+
aqueous
acetic acid
sodium acetate
+
carbon dioxide
+
water
Symbol Explanation
+ Separates two or more reactants or products
Yields - separates reactants from products
→;←;↔ Reversible reaction
(s); (l); (g) solid, liquid or gas
(aq) Aqueous solution – a substance dissolved in water
Heat supplied
Platinum used as a catalyst
heat
→
→Pt
Chemical Equations The physical state of the substances can
be indicated by placing a symbol in parenthesis after the formula
C12H24(s) + O2(g) CO2(g) + H2O(g)
(s) For solid, (l) for liquid, (g) for gas, and (aq) for an aqueous solution.
Heat
Chemical Equations What would the skeleton equation be
for the following: Sulfur burns in oxygen to produce sulfur
dioxide.
S(s) + O2(g) Heat SO2(g)
Chemical Equations What would the skeleton equation be for
the following: When solid potassium is added to water,
hydrogen gas and aqueous potassium hydroxide are produced
K(s) + H2O(l) H2(g) + KOH(aq)
Homework Read 61-63 Reactions 8 and Balancing Chemical
Equations
Balancing Chemical Equations
Rules for Balancing Equations
1. Determine the correct formula of all reactants and products
2. Write reactant on the left and products on the right side of the arrow.
3. Count the total number of atoms of each element on each side.
Balancing Chemical EquationsRules for Balancing Equations4. Balance the elements one at a time by using
coefficients – DO NOT CHANGE SUBSCRIPTS
5. Check each atom or polyatomic ion to make sure the equation is balanced
6. Make sure all coefficients are the lowest possible ratio that balances
Let’s see how it is done…
Balancing Chemical EquationsBalance the following equations:
SO2 + O2 SO3
Fe2O3 + H2 Fe + H2O
P + O2 P4O10
Al + N2 AlN
Balance the following equations:2SO2 + O2 2SO3
Fe2O3 + 3H2 2Fe + 3H2O
4P + 5O2 P4O10
2Al + N2 2AlN
More Practice…
Balancing Chemical Equations