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Bell Work. Convert the following in to a word equation: H 2 + O 2 → H 2 O. Physical Science – Lecture 50. Types of Reactions. Elements. Have only 1 capital letter – can be found on the periodic table. Compounds. Have more than 1 capital letter. Types of Reactions.
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Bell Work • Convert the following in to a word equation: • H2 + O2 → H2O
Physical Science – Lecture 50 Types of Reactions
Elements • Have only 1 capital letter – can be found on the periodic table.
Compounds • Have more than 1 capital letter
Types of Reactions • 1. Direct Union (or Combination) Reactions • 2. Combustion Reactions • 3. Single Displacement Reactions • 4. Double Displacement (or Metathesis) Reactions • 5. Decomposition Reactions
1. Direct Union or Combination Reactions • A reaction where two or more elements or compounds make one compound.
Example • H2 + Br2 → HBr
2. Combustion Reactions • A compound reacts with an element to form two compounds.
All Combustion Reactions • Combustion reactions occur between a hydrocarbon and oxygen. • The reaction forms carbon dioxide and water.
What is a hydrocarbon? • A hydrocarbon is a compound that only contains hydrogen and carbon. • Occasionally, it will contain oxygen.
Examples • C3H8 + 5 O2 → 3 CO2 + 4 H2O • 2 C4H10 + 9 O2 → 8 CO2 + 10 H2O • C2H5OH + 3 O2 → 2 CO2 + 3 H2O
3. Single Displacement Reactions • An element reacts with a compound to form a new element and compound.
Example • Al + HgCl2 → AlCl3 + Hg
Example • Cu + 2 AgNO3 → Cu(NO3)2 + 2 Ag • Fe + CuSO4 → FeSO4 + Cu
Example • Cl2 + 2 NaI → 2 NaCl + I2
4. Metathesis or Double Displacement Reactions • Double Displacement occurs when two compounds react to form two new compounds. • It usually occurs in water solutions.
What must happen? • One or both of the products must become unavailable for the reverse reaction or the reaction will not happen.
Three Ways to Prevent Reversal • (1) Formation of an insoluble compound • (2) Formation of a gas – that leaves the solution • (3) Formation of water – neutralization reaction
Examples • Na2S (aq) + 2HCl (aq) → 2NaCl (aq) + H2S (g) • AgNO3 + NaCl → AgCl(s) + NaNO3 • BaCl2 + K2SO4 → BaSO4(s) + 2 KCl • HCl + NaOH → NaCl + H2O • H2SO4 + Mg(OH)2 → MgSO4 + H2O
5. Decomposition Reactions • Decomposition is the reverse of combination/direct union. • A single compound is broken down into two or more elements/compounds.
Decomposition Example • Cu(NO3)2 → CuO + NO2 + O2 • 2 HgO → 2 Hg + O2 • 2 KClO3 → 2 KCl + 3 O2 • CaCO3 → CaO + CO2
How to Predict Reaction Types • Step 1 – Identify the reactants and products as elements or compounds. • Step 2 – Find the reaction type that has the same pattern as what’s labeled in Step 1.
When copper reacts with silver nitrate, solid silver crystals and copper (II) nitrate are formed.
When C5H9O reacts with oxygen gas, carbon dioxide and water are formed.
When lithium hydroxide reacts with hydrogen bromide, lithium bromide and water are formed.