Chemical Reactions #1 Writing Chemical Reactions In order to be able to write a chemical reaction, you MUST know how to write formulas from names! If you still cannot do thisyou are going to have MAJOR trouble Steps for Balancing Chemical
Equations Write the __________ equation for the reaction Count the number of atoms of each element of the __________ Count the number of atoms of each element of the
__________ Add / Change the __________ to make the numbers of each element equal YOU CAN NEVER CHANGE A SUBSCRIPT! Write the coefficients in the __________ possible ratio Check your work Example Write and balance the reaction between sodium hydroxide and calcium bromide to give calcium hydroxide and sodium
bromide Small Intro to Redox (MUCH more on this later!) A reaction in which electrons are transferred from one atom to another is called an ____________________ reaction. Determining Oxidation Numbers
1. The oxidation number for any uncombined 2. 3. 4. elements or diatomic molecule is __________ The oxidation number for a monatomic ion is its __________ The oxidation number of Hydrogen is usually __________ . The exception is in a __________ where the oxidation number will
be -1 The oxidation number of oxygen is usually __________ EXCEPT in __________ . Then it is -1 Determining Oxidation Numbers 5. In binary compounds (nonmetal + nonmetal) the more electronegative element gets a negative oxidation number.
This usually means the positive one is first and the negative one is second 6. The sum of the oxidation numbers for all atoms 7. in a neutral compound is __________ The sum of the oxidation numbers in a polyatomic ion is equal to the __________ of
the polyatomic ion Equations __________ equations show the complete chemical formulas. Does not indicate ionic character __________ equation shows all ions. Actually how the particles exist in the solution
Steps for Writing Ionic Equations 1. Write the balanced molecular equation (balanced chemical equation) 2. Break every thing down into its ions EXCEPT the __________ , __________, __________ , or ______________ (complete ionic equation) 3. Cross out everything that is the same on both sides (__________ ions)
4. Write what is left (net ionic equation) Rules When writing ionic equations, you must keep together the solid, gas, water, or weak electrolyte Spectator ions ions that appear on both sides of the equation. They have very little to do with the chemical reaction
A few more things that you must know When writing ionic reactionsyou must be able to identify the solid, gas or weak electrolyte In order to know what is solidyou MUST memorize the solubility rules You must also be able to identify strong
electrolytes They are all strong acids & bases Strong acidsHCl, HBr, HI, HClO3, HClO4, HNO3, HIO4, H2SO4 Strong basesall group 1A & 2A hydroxides Solubility Rules Classification of Reactions There are 5 major classifications of
reactions: __________(Combination) __________ __________ _______________________
_______________________(Metathesis) Synthesis # 1 1. Metal oxide + nonmetal oxide salt (Not Redox) Synthesis # 1 Example Sulfur dioxide gas is passed over solid calcium oxide Synthesis # 2
2. Metal oxide + water base (Not Redox) Solid sodium oxide is added to water Synthesis #3 3. Non metal oxide + water acid Sulfur dioxide gas is placed in water Synthesis # 4 4. Metal + nonmetal salt (RedoxNO IONS) A salt is just an ionic compound ( a positive
charge & a negative charge) Magnesium metal is combusted in nitrogen gas Decomposition Synthesis Decomposition Redox Metal + Nonmetal
salt Salt Metal + Nonmetal Non Redox Metal oxide + H2O base base Metal oxide + H 2O
Nonmetal oxide + H2O acid acid Nonmetal oxide + H2O Metal oxide + Nonmetal oxide salt
salt Metal oxide + Nonmetal oxide More Decomposition Metal chlorates metal chloride + O2 (NH4)2CO3 2NH3 + H2O + CO2
2H2O2 2H2O + O2 If you get any of these productsthey decompose NH4OH NH3 + H2O H2CO3 CO2 + H2O H2SO3 SO2 + H2O HNO2 NO + NO2 + H2O
