AP Chemistry Student Notes 4.1-4.4 PDF

key Name: ___________________________________________________________ Period: _________ Lecture 3 Introduction to Reactions and Net Ionic Equations (AP Chemistry Topics 4.1, 4.2, 4.3)...

key Name: ___________________________________________________________ Period: _________ Lecture 3 Introduction to Reactions and Net Ionic Equations (AP Chemistry Topics 4.1, 4.2, 4.3) Student Notes Enduring Understanding Learning Objective(s) A substance that changes its properties, or that Identify evidence of chemical and physical changes in changes into a different substance, can be represented matter by chemical equations. Represent changes in matter with a balanced chemical or net ionic equation: For physical changes. For given information about the identity of the reactants and/or product. For ions in a given chemical reaction. Represent a given chemical reaction or physical process with a consistent particulate model Changes in Matter A physical change occurs when a substance undergoes a change in properties but not a change in ___________________________________ composition ___________________. The identity of the substance does not change, no new bonds are formed and it is typically a reversible change Examples of physical changes include phase changes, separation techniques, and dissolving. Evidence of chemical changes include: A chemical change occurs when substances are precipitate (a substance of a Production of a __________________ transformed into new substances, typically with new phase, such as the solids forming from a solution) different compositions ________________ ____________________. The Change in __________ color identity of the substances changes, new bonds are formed and these reactions are typically irreversible. temperature Change in ___________________ sound light or __________ Production of __________ Gas production (_____________) bubbles  The Language of Chemical Reactions Chemical Equations are written representations of chemical reactions 2 Na (s) + 2 H2O (l) → 2 NaOH (aq) + H2 (g) Reactants are the substances you start with and they are found on the left side of the arrow. __________________ Products are the substances that you end with and they are found on the right side of the arrow. _________________ We often specify the state of matter for each substance in parentheses next to its L I chemical formula i C Coefficients balance a chemical equation and tell us the ratio of how substances react Example: 2 moles of Na react with 2 moles of H2O to produce 2 moles of NaOH and 1 (aa) mole of H2 Chemical Equations and Physical Changes During a physical change, there is no change in the composition of the substance. identity of the reactant will be the _________ In the chemical equation, the _______________ same as the product Write a chemical equation that shows solid sodium Write the chemical equation that shows solid carbon melting into liquid sodium. dioxide subliming into gaseous carbon dioxide Nacs) -> Nace) CO2 is) -> CO2 (g) Dissolving Dissolving is a type of physical change where the composition doesn’t technically change, and it can be easily reversed. Recall: dissociate When ionic compounds dissolve, they ____________________ (break apart) into their ions When molecular compounds dissolve, they do not dissociate. The bonds holding the atoms together remain intact This affects the way we write chemical equations for dissolution Dissolution of Salt (ionic) NaCl (s) → Na+ (aq) + Cl- (aq) Dissolution of Sugar (molecular) C12H22O11 (s) → C12H22O11 (aq)  Write the chemical equation showing KCl(s) dissolving in Write the chemical equation showing Al(OH)3(s) water dissolving in water KClis) -> Kans + CTaa) AlCOH) s is -> Alags + 3 OHIan) Write the chemical equation showing CaO(s) dissolving in Write the chemical equation showing Al2(PO4)3(s)Alz(SO4)3 - - - - - water dissolving in water CaUis) - CaYas + O can) Alz(S04)s is 2 Alans+ 350yag) Chemical Equations and Chemical Changes During a chemical change, substances are converted into new substances with different compositions. identity In the chemical equation, the ________________ of the reactant(s) will be different ___________________ from the product(s) The 5 main types of chemical reactions are synthesis, decomposition, single displacement, double displacement, and combustion Balancing Equations The Law of Conservation of Matter states that matter cannot be created or destroyed. All physical and chemical changes in matter can be represented by balanced chemical equations balanced equation demonstrates that mass is conserved in A __________________ chemical reactions because the number and type of atoms are the same on both sides! The Rules of the Balancing Game Matter cannot be created or destroyed By the time you finish balancing an equation, there should be the same number of atoms on BOTH sides of the equation. Subscripts can NEVER be added, removed, or changed. Changing subscripts changes the identity of the chemical. This is never allowed. You can only change coefficients. Coefficients can only go in front of chemical formulas...NEVER in the middle of a formula.  6 ____K 32 + ____B2O3 → ____K 2O + ____ B + 62 single replacement rx ____Mn 2 + ____CuCl 3 3 3 → ____MnCl2 + ____ Cu 2 3- Mn-3 I is z-o 6- - 2 single replacement rx 3 __ NH4Cl + __ Na3PO4 → __ (NH4)3PO4 + 3 __ NaCl A keep polyatomics 35 3 easier together for NH4 1 PO4 I 35 cl +3 double replacement balancing 3 Na + 3 rx __ Mg3(PO4)2 + 2 __ Al(NO3)3 → 3 __ Mg(NO3)2 + 2 __ AlPO4 Mg + 3 2 E PO4 Al i - - 2 2 65 NO3 - 2 6 double replacement rx __ 2 C2H6 + __ 2 __ CO2 + B 7 O → 24 _ H2O E - 7 combustion reaction 2 __ C4H10 + __ __ CO2 +105 13 O2 → 8 -_ H O 2 is I is combustion reaction Writing Balanced Chemical Equations We can write balanced chemical equations from word equations. Write a balanced equation for the reaction between aqueous strontium chloride and aqueous lithium phosphate to form solid strontium phosphate and aqueous lithium chloride 3SUCI caas+2LigPOY caas - Siy(PO4)2cs) +6LiC)(aa) Write a balanced equation for the reaction between zinc (II) iodide and chlorine gas to form zinc (II) chloride and iodine gas znFz(aa) Cl2(g) -> InClcan) + Iz (y) + * balanced as written Write a balanced equation for the reaction between aqueous lead (II) nitrate and aqueous potassium iodide to form solid lead (II) iodide and aqueous potassium nitrate Pb(NO3) : caq) + 2 KIcan) -> PbIzcs + 2 kNOscaal Write a balanced equation for the reaction between solid cobalt (III) oxide and solid carbon to produce solid cobalt and carbon dioxide gas 200203(3) + 36(s) - 40(x) + 3C02 (9) Write a balanced equation for the reaction between gaseous ethane (C2H6) and oxygen gas to form gaseous carbon dioxide and water vapor. 2C2Hy(q) +702(9) -> 4C02(a) GHz0ca) + Representation of Reactions A physical or chemical process can be represented using a A physical or chemical process can be represented using a chemical equation ________________________________ which contains particulate diagram ____________________________________ to represent formulas, states of matter, and coefficients the reaction on a molecular level States of Matter tightly packed Solid: particles should be ___________________________ together Liquid: particles should be somewhat close to each other disordered to show the flow of the liquid and _________________ very far apart Gas: particles should be _________________________ and fill the space of the container Aqueous solution: ions should be dissociated  Particles two atom a atomic Diatomic elements: Elements that are _________________ should be represented as __________________ joined together Don’t forget Professor BrINClHOF! Chemical Formulas: When given a chemical formula, use the correct number of atoms for each element in the compound Size: atoms of the same element should be the same size and atoms of different elements should follow size trends on the periodic table. Conservation of Matter Make sure your diagrams obey the law of conservation of matter Conservation of Matter The number and type of atoms are the When there is a limiting reactant, make sure to include all same before and after the reaction ___________ remaining the species ___________________ at the end of the reaction. Balanced equations can help you determine how much product can be formed from reactant mixtures In this example, O2 is limiting and H2 is in excess. When the reaction is complete, there is still H2 in the container and it should be drawn.  Precipitation Reactions Recall that a double exchange reaction occurs when two ionic compounds switch partners and form two new compounds. A special type of double exchange reaction, where two solutions react and an insoluble solid product is formed, is called a precipitation reaction solid precipitate is the _______________ The ___________________ that emerges from the solution. Solubility Rules You MUST memorize the following rule: We can determine which product is the precipitate based on solubility rules All Group 1 (Na+, K+, etc), ammonium (NH4+) and nitrate (NO3-) salts are always soluble (aq) Ionic Compound State of Matter These other rules will be implied or given to you: Na2SO4 aq - Halides (Br-, Cl-, I-) are soluble (aq) except when combined with Ag+, Hg+ or Pb+2 (s) Cu(OH)2 - S All carbonate (CO3-2), phosphate(PO4-3) are insoluble (s) PbI2 - S except when combined with the ions listed above K3PO4 - aq All hydroxides (OH-) are insoluble (s) except when combined with the ions listed above and Ba(OH)2 (aq), AgNO3 - aq Sr(OH)2(aq), and Ca(OH)2(aq) Types of Chemical Equations Balanced Molecular Equations: This equation shows all the species participating in the chemical reaction Complete Ionic Equations: This equations shows aqueous ionic compounds as separate charged particles. Spectator ions can be identified from this equation Spectator ions: ions that do not participate in a chemical reaction and are present on both sides of the equation Net Ionic Equations: This equation represents only the substances undergoing a chemical change. It does not include spectator ions  Writing Equations for Precipitation Reactions Sodium hydroxide solution reacts with copper (II) sulfate solution to form sodium sulfate and copper (II) hydroxide. Balanced Molecular Equation 2NaOH cans + CuSO4caal - NazSOycaas + (nCOH)2cs) Complete Ionic Equation: Nations 20tians Culaas Sonaas * 2 Natas SOyans + 2 + CuCOH)2 is + Net Ionic Equation: 2 OHTaas + Cutaas -> CuLOH) is / Spectator Ions: NaT , Soy2- Balanced Molecular Equation 2 HI(aq) + Ba(OH)2(aq) → 2 H2O(l) + BaI2(aq) Complete Ionic Equation: 2H caas + 2 Finas + Baaas+ 20tiaas-> 2 H20c) + Bataas + 2↓ - Taal Net Ionic Equation: 2Acaal + 2 OHTaal -> 2 H20(1) Spectator Ions: Batz , I Lead (II) nitrate reacts with potassium chloride to produce lead (II) chloride and potassium nitrate Balanced Molecular Equation Pb(NO3)c caas + 2 KC)(aq) -> PbC12 (s) + 2KNOs caal Complete Ionic Equation: Pbans + 2NOscaas + 2 KTcaas+ 2Cliaas -> PbC12cs) + 2 Kcaas + 2 NOsan) Net Ionic Equation: + Pb 2 Cl -> PbC12cs) + caa) caas Spectator Ions: + k , NOz-  Potassium phosphate reacts with aluminum chloride in a double replacement reaction Balanced Molecular Equation 43POy(ags + AlCcaas -> 3KC)caas + AlPOycs) Complete Ionic Equation: 3 KTanst PryTags Alas + + 3Clans - 3Kcaus+3Clans t AlPOYCS) Net Ionic Equation: Alcaas + POYY caas -> AlPO4 (s) Spectator Ions: k+ Cl- , Ammonium nitrate reacts with sodium chloride in a double displacement reaction Balanced Molecular Equation NAyNUscans + NaCIas - NHyCcans + NaNOs (aal Complete Ionic Equation: NAyTags + NOscans + Natcaas + Clas -> NHytcaas + Cliaast NaTcaas + NO caa) Net Ionic Equation: No Net Reaction Spectator Ions: NHyT Nat T NOs , , CI- , Calcium hydroxide reacts with iron (III) chloride in a double displacement reaction Balanced Molecular Equation 30a(OH)2 (aa) +2 FeCIscans - 3 CaCl2 +2 FeCOH)s (s) (ay) Complete Ionic Equation: 3CaTags + 60Hinas + 2Fe"ans + 6Clcans - 3CaTas + 6 Claast2FeCOH)scs) Net Ionic Equation: 60Hcaal +IFecaal * 2 Fe (OH) 3 (s) Spectator Ions: Ca2+ , Cl-  2 KI(aq) + Pb(NO3)2(aq) → 2 KNO3(aq) + PbI2(s) Particulate Diagram for Precipitation Reactions Guidelines: The precipitate is a solid and Draw a particulate diagram for the following precipitation reaction: should be shown at the bottom of the beaker NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s) Aqueous species should be shown in solution Agt Nat - Nat Cl- NOs NOs NOS Nat AgT I Na Cl- NO5 Ste Potassium phosphate reacts with an EXCESS of aluminum nitrate. Draw all of the species present at the end of the reaction. 13POy # Al(NO3)s - + kNO3 (aal AlPO4 Cs) Alst ↑ kt excess kt so there will be extra NOs Al3+ floating NOs around in not AlPOYLS) Me AIPOy (S) EXCESS Manganese (II) chloride reacts with ammonium carbonate. Draw all of the species present at the end of the reaction. MuCI + (NH-D2COs - - Cl NHyCIcaa) NH + MuCOscs) ↑ Niy so there excess extra Mut Cl Mut will be not Miss around floating in MnCO3 (s)