Presentation on theme: "Stoichiometry and Reactions"— Presentation transcript:
1 Stoichiometry and Reactions Chapter 3A & 4AStoichiometry and Reactions
2 Chemical ReactionsChemical equation – a representation of a chemical reaction. Reactants – the starting chemicals. Products – the ending chemicals. CH4 + O2 → CO2 + H2O Reactant Product Conservation of matter – in a chemical reaction, atoms are neither created nor destroyed.
3 Physical States Solid (s) Liquid (l) Gas (g) Dissolved in water (aq) The state of the compound can be stated in the reaction equation using the following symbols.Solid (s)Liquid (l)Gas (g)Dissolved in water (aq)
4 Balancing EquationsC(s) + O2(g) → CO2(g) Reactants Products All atoms present in the reactants must be accounted for among the products C-1 → C-1 O-2 O-2
5 Balancing RulesRead the description and write the formulas for the reactants and products.Write the unbalanced formula.Balance the equation starting with the most complicated molecule. Remember to not change the formula of the chemicals.Check to confirm balance.
6 Balancing EquaitonsMethane reacts with oxygen to produce carbon dioxide and water. CH4(g) + O2(g) → CO2(g) + H2O(l) C-1 C-1 H-4 H-2 O-2 O-3
8 Balancing EquationsHydrogen gas combines with oxygen gas to produce water.Sodium metal combines with water to produce sodium hydroxide liquid and hydrogen gas.Aluminum solid combines with chlorine gas to produce aluminum chloride solid.Hydrochloric acid (aqueous solution) combines with calcium carbonate solid to form calcium chloride, carbon dioxide gas and water.
9 Reaction Types Composition (synthesis) Decomposition Single ReplacementDouble replacement (precipitation)Acid/Base
10 Reaction TypesComposition reaction – a reaction that combines substances to form a single substance. A + B → C 2H2 + O2 → 2H2O C + O2 → CO2 2Na + Cl2 → 2NaCl
11 Reaction TypesDecomposition reaction – a reaction in which a compound is broken down into two or more simpler substances. AB → A + B 2H2O → 2H2 + O2 2NaCl → 2Na + 2Cl CaCO3 → CaO + CO2
12 Reaction TypesSingle replacement reaction – a reaction in which one element takes the place of another element A + BC → B + AC Cu + 2AgNO3 → Cu(NO3)2 + Ag 2K + 2H2O → H2 + 2KOH
13 Reaction TypesDouble replacement reaction – a reaction in which two different compounds exchange positive ions and form two new compounds. AB + CD → AD + CB Pb(NO3)2 + KI → PbI2 + 2KNO3 CaCO3 + 2HCl → CaCl2 + H2CO3
15 Single Replacement Reaction If the free metal is higher on the metal activity table than a metal in solution then the free metal will exchange places with the metal in solution. Ex. Zn + HBr → NiCl2 + K → Cu + HCl →
16 Double Replacement Reaction Prediction Metathesis reactions are driven by three "driving forces." 1) A product is a precipitate 2) A product is a gas 3) A product is a weak or non-electrolyte We reduced these to; 1) A product is an ionic precipitate 2) A product is a molecular, non-strong acid
17 Double ReplacementThe solubility table is used to determine if an ionic precipitate is formed from the reactants. Ex. K2S + Fe(NO3)2 Na2SO4 + BaCl2 HCl + MgS KI + NH4NO3
18 Double Replacement Reaction Molecular equation – equation in which the complete formulas of all reactants and products are given.Complete ionic equation – equation in which all substances that are strong electrolytes are represented as ions.Spectator ions – ions which do not participate in the reaction.Net ionic equation – equation in which the spectator ions are not represented only the components involved in the reaction.
19 Double Replacement Reaction For each of the following reactions, write the balanced molecular equation, the balanced complete ionic equation, and the balanced net ionic equation.Silver nitrate and sodium chromateAgNO3 + NaCrO4Nickel(II) nitrate and potassium carbonateNi(NO3)2 + K2CO3
20 ElectrolytesStrong Electrolytes – ionic compounds that total dissociate in water and conduct electricity.Weak electrolytes – molecular acids that can totally or partially dissociate in water.Non electrolytes – molecular compounds that do not dissociate in water so do not conduct electricity.
21 Acid/Base ReactionsAcids – substances that ionize in aqueous solutions to form hydrogen ions. H2SO4(aq) → H+(aq) + HSO4-(aq) Strong acids – strong electrolytes Bases – substances that ionize in aqueous solutions to form hydroxide ions. NaOH(s) → Na+(aq) + OH-(aq)
23 Acid/Base ReactionsAcid/Base reactions result in the formation of a salt and water Ex. Write the balanced molecular, balanced complete ionic, and balanced net ionic equations for the reaction of aqueous hydrobromic acid and aqueous sodium hydroxide.
24 Acid/Base ReactionWrite the balanced molecular, balanced complete ionic, and balanced net ionic equations for the reaction of aqueous sulfuric acid and aqueous potassium hydroxide.