Chemical Reactions Chemical rxns occur when atoms are: Separate d As reactants turn into products,...
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Transcript of Chemical Reactions Chemical rxns occur when atoms are: Separate d As reactants turn into products,...
Chemical Reactions
Chemical rxns occur when atoms are:
Separated
As reactants turn into products, what happens to
bon holding atoms together ?Old Bon are broken &
new Bon are formed
Chemical rxnChemical rxn
or rear
joined
ranged
ds
Atoms of 1 element never change into other elements in chemical rxn’s (only Nuclear rxns).
Why?Atoms - neither created nor destroyed just rearranged in
chemical rxns.
Reactants
Arrow, which means:
Yields, Reacts to produce, To produce
Products
What symbol separates the reactants from the products?
_____________ _____________
Reactant 1 + Reactant 2 Product 1 + Product 2
“Reacts with” to separate 2 reactants
“and” is used to separate 2 products
Reactants, productsReactants, products
Left side is called? Rt. side is called?
II. Writing Chemical Equations
A. Chemical equation:describes reactants & products
Chemical equations - described 2ways:
Written Words
Skeletal Equation
Writing chemical eqWriting chemical eq
Rules for writing chemical eq.
1. Include physical states
Solid (s), Liquid ( l ), Gas (g), Aqueous (aq)
2. Some elements ONLY appear as diatomics
H2 O2 F2
rulesrules
3. Some rxns require a catalyst.
Catalyst speeds up rxn - not part of product
Aqueous means dissolved in water
Br2 I2 N2 Cl2
4. the catalyst - written above or below .
KI
MoS2
rulesrules
5. If heat is a catalyst, use a above
What happens if both heat & a chemical are catalysts?
A. Written Words
Ex 1: Fe (s) + O2 (g) Fe2O3 (s), interpret
Solid iron
to producesolid
reacts withoxygen gas
iron (III) oxide.
Written words, ex 1Written words, ex 1
Why is oxygen in the example
written as O2?
Written Words
Example 2: KOH (aq) + H2SO4 (aq) H2O (l) + K2SO4 (aq)
Aqueous potassium hydroxide to yield water
reacts with
aqueous sulfuric acid
and
Written words, ex 2Written words, ex 2
aqueous potassium sulfate.
C. Skeletal Equation
What is a skeletal equation?
MnO2 H2O (g)H2O2 (aq) +
skel eq, ex written as symbolsskel eq, ex written as symbols
O2(g)
Ex 1: Manganese (IV) oxide catalyzes the decomposition of aqueous hydrogen peroxide into water vapor and oxygen gas.
Skeletal Equation
Ex 2: Solid sodium reacts with water to produce aqueous sodium hydroxide and hydrogen gas.
Na (s) NaOH (aq) +H2O(l) +
skel eq, ex written as symbolsskel eq, ex written as symbols
H2(g)
Why is hydrogen gas written as
H2?
Skeletal Equation
Ex 3: Solid sodium hydrogen carbonate reacts with a solution of hydrochloric acid to produce aqueous sodium chloride, water and carbon dioxide gas.
NaHCO3(s) NaCl (aq) +HCl(aq) +
skel eq, ex written as symbolsskel eq, ex written as symbols
H2O (l) + CO2(g)