Introduction to Types of Chemical Reactions

I can identify elements vs. compounds in a chemical equation Objective I can identify elements vs. compounds in a chemical equation I can name the 7 diatomic elements I can identify precipitation vs. redox reactions

Review: Compounds vs. Elements Compounds are combinations of elements that are chemically combined. examples: H2O2 CO2 H2O C4H8 Fe2O3 When not in a compound, most elements exist as single atoms but seven elements exist as diatomic molecules There are 7 diatomic elements H2, O2, F2, Br2, I2, N2, Cl2

H2, O2, F2, Br2, I2, N2, Cl2 there are 7 diatomic elements

Boron as B2 Carbon as C2 Oxygen as O2 Helium as He2 Which of the following would appear as a diatomic element in a chemical reaction? Boron as B2 Carbon as C2 Oxygen as O2 Helium as He2 [Default] [MC Any] [MC All]

Chemical Reactions Every minute of the day chemical reactions take place. In your body, complex chemical reactions digest food. Plants use sunlight to drive the photosynthesis reaction. A chemical reaction produces electrical energy in your car battery An undesirable chemical reaction with oxygen occurs with your car fender to produce rust.

Describing Chemical Reactions Describing chemical reactions using balanced chemical equations is an essential skill. reactants → products Symbols you might see in a balanced chemical equation: (s) solid (l) liquid (g) gas (aq) aqueous – dissolved in water D (above the arrow) indicates the reactants are heated

Example When solid sodium hydrogen carbonate is heated, it decomposes, forming the products solid sodium carbonate, carbon dioxide gas and water vapor. Write the Chemical Equation:

What does the symbol (s) after Na(HCO3) stand for in this chemical equation? solution solid substance sodium [Default] [MC Any] [MC All]

What does the symbol (g) after CO2 stand for in this chemical equation? grams group gas ground state [Default] [MC Any] [MC All]

Two categories of Chemical Reactions Chemical reactions can be categorized into two types; Precipitation reactions. Oxidation – Reduction reactions called redox In a precipitation reaction, cations and anions in aqueous solution are rearranged to form a solid product called a precipitate. In an oxidation – reduction reaction (or redox reaction), electrons are lost by one element and gained by another element.

Examples of Reactions Precipitate Reaction examples: AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq) Na2S(aq) + Cd(NO3)2(aq) → CdS(s) + 2NaNO3(aq) BaCl2(aq) + K2CO3(aq) → BaCO3(s) + 2KCl(aq) Pb(ClO4)2(aq) + 2NaI(aq) → PbI2(s) + 2NaClO4(aq) What do these reactions have in common?

Examples of Reactions Redox reaction examples: 2K(s) + Cl2(g) → 2KCl(s) 2H2O2(aq) → 2H2O(l) + O2(g) 2Al(s) + 3Cu(SO4)(aq) → 3Cu(s) + Al2(SO4)3(aq) Pb(s) + 2 AgNO3(aq) → 2 Ag(s) + Pb(NO3)2(aq) CH4(g) + O2(g) → CO2(g) + 2 H2O(l) What do these reactions have in common?

Compare reactants cations & anions are rearranged precipitation reactions redox (oxidation-reduction) reactions reactants cations & anions are rearranged aqueous solutions react to form a precipitate (aq) + (aq)  (s) + (aq) a precipitate is a solid formed in a solution reactants & products are ionic compounds – NOT elements electrons are lost by one element and gained by another element typically a reactant or product or both is an element elements can be diatomic molecules H2, O2, N2, F2, Br2, I2, Cl2 Compare

Identify as precipitation or redox reaction: H2(g) + F2(g) → 2 HF(g) precipitaiton redox [Default] [MC Any] [MC All]

Identify as precipitation or redox reaction: Identify as precipitation or redox reaction: 2Al(s) + 3Cu(SO4)(aq) → 3Cu(s) + Al2(SO4)3(aq) precipitaiton redox [Default] [MC Any] [MC All]

Identify as precipitation or redox reaction: 2NaOH(aq) + MgCl2(aq) → Mg(OH)2(s) + 2NaCl(aq) precipitaiton redox [Default] [MC Any] [MC All]

Identify as precipitation or redox reaction: Identify as precipitation or redox reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) precipitaiton redox [Default] [MC Any] [MC All]

Identify as precipitation or redox reaction: MgCl2(s) → Mg(s) + Cl2(g) precipitaiton redox [Default] [MC Any] [MC All]

Identify as precipitation or redox reaction: Na2S(aq) + Cd(NO3)2(aq) → CdS(s) + 2NaNO3(aq) [Default] [MC Any] [MC All]

Identify as precipitation or redox reaction: 2 Al(s) + 3 Cu(SO4)(aq) → 3 Cu(s) + Al2(SO4)3(aq) [Default] [MC Any] [MC All]

I can identify elements vs. compounds in a chemical equation Objective I can identify elements vs. compounds in a chemical equation I can name the 7 diatomic elements I can identify precipitation vs. redox reactions