Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
Chapter 8
Chemical Reactions
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Balance chemical reactions.
Determine the type of chemical reactions by using the reactants.
Predict products of reactions.
Write word equations for chemical reactions.
Determine precipitates in the lab.
Reactants ­ Substances that enter into a reaction.
Products ­ Substances that are formed by a reaction.
Reactants ­­­­­> products
before during after
3A2B
A Coefficient
B
A A Subscript
A B
B
A A precipitate aqueous ­ substance is dissolved in water
catalyst ­ a substance that speeds up the rate of a reaction without being consumed by the reaction
precipitate ­ a solid formed from the combination of two solutions
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
Example of a chemical reaction.
Solid magnesium chlorate will decompose when heated to form solid magnesium chloride with molecules of oxygen driven off. The magnesium chlorate is composed of one magnesium ion combined with two chlorate ions. The charge of the magnesium ion is positive two, the charge of the chlorate ion is negative one. Chlorate is composed of one atom of chlorine covalently bonded with three atoms of oxygen. A formula unit of magnesium chloride is composed of one magnesium ion and two chloride ions each with a charge of negative one. A molecule of oxygen is composed of two oxygen atoms. One unit of magnesium chlorate will decompose to form one unit of magnesium chloride and three molecules of oxygen.
2+
1­
2+
1­
2Mg(ClO3)2 (s) ­­­> 2MgCl2 (s) + 3O2
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
Steps to balancing chemical reactions:
1. Write a word equation showing all reactants and products.
2. Write a formula for each reactant and product. Use subscripts to balance ionic compounds. Use subscripts to correctly write covalent compounds and acids. Never add, remove, or change a subscript once formulas are correctly written.
3. Balance the reaction with coefficients to satisfy the law of conservation of matter.
4. Use other symbols when required; ie, (s), (l), (aq), etc. Examples:
Hydrogen:
Oxygen:
Water:
1. Hydrogen + oxygen ­­­­> water
+
Before
After
+
Before
After
+
Before
After
2 H2 + O2 ­­­> 2 H2O
hydrogen + oxygen → water
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
Example 2:
potassium hydroxide + phosphoric acid ­­­> potassium phosphate + water
If a polyatomic ion is not separated, it can be balanced by the whole ion.
Metals usually balance easiest
Hydrogen and oxygen are the hardest
Example 3:
phosphorus pentachloride + water ­­­> phosphoric acid + hydrochloric acid
Since the hydrogen is split, and the oxygen is not, balance the oxygen first.
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
Red Check Examples
2. aluminum + oxygen ­­­­­> aluminum oxide
4 Al + 3 O2 ­­­­­­­> 2 Al2O3
3. sodium chlorate + lead IV nitrate ­­­­­­> lead IV chlorate + sodium nitrate
4 NaClO3 + Pb(NO3)4 ­­­­­­­> Pb(ClO3)4 + 4 NaNO3
4. iron III oxide + carbon monoxide ­­­­­­> iron + carbon dioxide
Fe2O3 + 3 CO ­­­­­­­> 2 Fe + 3 CO2
5. ammonium dichromate ­­­­­> nitrogen + chromium III oxide + water
(NH4)2Cr2O7 ­­­­­­­> N2 + Cr2O3 + 4 H2O
6. ethane + oxygen ­­­­­­> carbon dioxide + water
2 C2H6 + 7 O2 ­­­­­­­> 4 CO2 + 6 H2O
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
Types of Chemical Reactions
I. Composition or Synthesis Reactions
Simple substances will combine to form a complex substance
A + B ­­­­> AB more than one reactant only one product
1. zinc + chlorine ­­­­­> 2. sulfur + lithium ­­­­­­­­>
3. magnesium oxide + water ­­­­­­­> 6
Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
II. Decomposition Reactions
Complex substances will break down into two or more simple substances.
A ­­­­­> B + C
B and C may be elements or compounds.
There can only be one reactant.
1. Mercury II oxide ­­­­­­­> 2. aluminum chlorate ­­­­­­­­­> 3. hydrochloric acid ­­­­­­>
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
III. Single replacement reactions
More active substances will replace less active substances in compounds. A + BX ­­­­­> AX + B
or
X + BY ­­­­­> BX + Y
1. aluminum sulfate + potassium ­­­­­­> 2. barium + phosphorous acid ­­­>
3. barium+ water ­­­­>
4. bromine + sodium iodide ­­­­> 8
Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
IV. Organic Combustion Reactions
Fuels burn with oxygen to form carbon dioxide + water
Fuels: organic fuels, compounds containing carbon, hydrogen, and possibly oxygen.
fuel + oxygen ­­­­> carbon dioxide + water
1. methane + oxygen ­­­­> 2. glucose + oxygen ­­­­>
C6H12O6
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
May 22, 2017
V. Ionic or double replacement reactions
Ions switch places in solutions to form a precipitate or molecule.
Ax + By ­­­­­> Ay + Bx
1. potassium hydroxide + carbonic acid­­­>
2. barium hydroxide + aluminum nitrate­­­>
Page 860
3. sodium chromate + lead II nitrate­­­­>
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Chemistry 1 H Chapter 8 Notes Block 4.notebook
Types of Reactions:
C
composition
SR single replacement
I
ionic
May 22, 2017
D
Cu
decomposition
combustion
___ aluminum + lead II nitrate →
___ zinc + chlorine →
___ magnesium hydroxide →
___ ethyl alcohol + oxygen →
___ magnesium + oxygen →
___ sodium nitrate + nickel II chloride →
___ sodium + water →
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