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Balancing Equations and types of chemical reactions. What is a Chemical Equation?. An equation is a short-hand way of writing a chemical reaction. Reactants are on the left, products are on the right. Mg + 2HCl MgCl 2 + H 2 reactants products.
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What is a Chemical Equation? • An equation is a short-hand way of writing a chemical reaction. • Reactants are on the left, products are on the right. Mg + 2HCl MgCl2 + H2 reactants products
How is this Accomplished? • Chemical equations are balanced by adding coefficients in front of the substances in the equation. 1 MgF2 + 1 Li2CO31 MgCO3 + 2LiF • Never change the subscript to balance equations
Tips for Balancing Equations • 1. Balance metals first. • 2. Balance nonmetals except H and O. • 3. If polyatomic ions are conserved in the reaction, then try balancing them as a unit. • 4. Balance any remaining H’s and O’s.
Some practice problems: • Here are some practice problems. • 1. __NaCl + __BeF2 --> __NaF + __BeCl2 • 2NaCl + BeF2 2NaF + BeCl2 • 2. __FeCl3 + __Be3(PO4)2 --> __BeCl2 + __FePO4 • 2FeCl3 + Be3(PO4)2 --> 3BeCl2 + 2FePO4
3. __AgNO3 + __LiOH --> __AgOH + __LiNO3 • AgNO3 + LiOH --> AgOH + LiNO3 • 4. __CH4 + __O2 --> __CO2 + __H2O • CH4 + 2O2 --> CO2 + 2H2O • 5. __Mg + __Mn2O3 --> __MgO + __Mn • 3Mg + Mn2O3 --> 3MgO + 2Mn
7. Na + H2O NaOH + H2 • 2Na + 2H2O 2NaOH + H2 • 8. H2SO4 + Ca(OH)2 CaSO4 + H2O • H2SO4 + Ca(OH)2 CaSO4 +2 H2O
Types of Chemical Reactions • There are 5 overall types of chemical reactions: • 1. Synthesis or Combination • 2. Decomposition • 3. Single Replacement • 4. Double Replacement • 5. Combustion
Synthesis: A + B AB • Synthesis – “putting together” • H2(g) + Cl2(g) ----> 2HCl(g) • C(s) + O2(g) ----> CO2(g) • CaO(s) + H2O(l) ----> Ca(OH)2(s)
Decomposition: AB A + B • Decomposition – “breaking apart” • C12H22O11(s) ---->12C(s) + 11H2O(g) • Pb(OH)2(s) ----> PbO(s) + H2O(g) • 2Ag2O(s) ----> 4Ag(s) + O2(g)
Single Replacement: A+ BC B + AC • Single replacement reactions - When one element displaces another element in a compound • Zn(s) + H2SO4(aq) ----> ZnSO4(aq) + H2(g) • 2Al(s) + 3CuCl2(aq) ---> 2AlCl3(aq) + 3Cu(s) • Cl2(g) + KBr(aq) ----> KCl(aq) + Br2(l)
Double Replacement: AB + CD AD + CB • Double Replacement reaction – chemical reaction where two reactant ionic compounds exchange ions to form two new product compounds with the same ions. • AgNO3(aq) + NaCl(aq) ----> AgCl(s) + NaNO3(aq) • ZnBr2(aq) + 2AgNO3(aq) ----> Zn(NO3)2(aq) + 2AgBr(s) • H2SO4(aq) + 2NaOH(aq) ----> Na2SO4(aq) + 2H2O(l)
Combustion: Burning (add O2) • CH4(g) + 2O2(g) ----> 2H2O(g) + CO2(g) • C2H6(g) + O2(g) ----> H20(g) + CO2(g) • C3H8(g) + O2(g) ----> H2O(g) + CO2(g) • H2(g) + O2(g) ----> H2O(g) • Mg(g) + O2(g) ----> MgO(s)