GHW#9. Louisiana Tech University, Chemistry 100. POGIL Exercise on Chapter 4. Quantities of Reactants and Products: Equations, Patterns and Balancing

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1 GHW#9. Louisiana Tech University, Chemistry 100. POGIL Exercise on Chapter 4. Quantities of Reactants and Products: Equations, Patterns and Balancing Why? In chemistry, chemical equations represent changes in a symbolic form. There are chemical information that could be interpreted if someone learned how to extract them form the chemical equation. It is important to recognize the general features of a chemical reaction based on the structural changes to the chemical and the types of the compounds involved in the equation. When substances react according to chemical equations, they do so in simple ratios of moles as given by stoichiometric coefficients. It is also important that we understand the information contained in a chemical equation and apply them in problem solving. Learning Objectives Students should understand the following concepts: 4.1 Chemical Equations 1. Interpret the information conveyed by a balanced chemical equation 4.2 Patterns of Chemical Reactions 1. Recognize the general reaction types: combination, decomposition, displacement, and exchange. 4.3 Balancing Chemical Equations 1. Balance simple chemical equations Success Criteria The students should be able to interpret the information conveyed by a balanced chemical equation, recognize their patterns as general reaction types: combination, decomposition, displacement, and exchange, able to balance them. Resources Chemistry: The Molecular Science 2nd Ed., J. W. Moore, C.L. Stanitski and P.C. Jurs. Prerequisites High school chemistry: Definition of matter. Scientific method, Dalton s Atomic theory, Components of atoms: nucleus (proton and neutrons) and electrons. Atoms, molecules and ions. Names and formulas of chemical compounds. New Concepts Chemical Equations Oxygen + Hydrogen --> water O 2 (g) + 2 H 2 (g) 2 H 2 O(l); H= -572 kj Interpret the information conveyed by a balanced chemical equation: reactants and products, stoichiometric and coefficients and their sum, subscripts, physical sate, reaction conditions(heat, light), complete( ) vs. equilibrium( ), mole conversion factors (2 mol H 2 = 1 mol O 2 ;2 mol H 2 = 2 mol H 2 O) and themochemical data (exothermic and endothermic). Patterns of Chemical Reactions Following patterns in chemical reaction have been observed based on simplicity or complexity of reactants or the products, and type of reactants and products.

2 Classification based on simplicity/complexity of reactants/products Combination: A + B AB Other modifications: synthesis (simple to complex): CO 2 + H 2 O C 6 H 12 O 6 + O 2 Decomposition: AB A + B; E.g. KClO 3 KCl + O 2 Displacement a) Single Displacement: AX + Y YX + A: The reaction follows Activity series: Metals: Li> K>Ca>Na>Mg>Al>Zn>Cr>Fe>Ni>Sn>Pb>H>Cu>Hg>Ag>Pt>Au E.g. Fe + Cu(NO 3 ) 2 Fe(NO 3 ) 2 + Cu, Non-metals: F>Cl>Br>I E.g. Cl NaI 2 NaCl + I 2 b) Double Displacement (exchange- metathesis): AB + XY AY + XB E.g. Ca(OH) HNO 3 Ca(NO 3 ) 2 + 2H 2 O Classification of reactions based on type of reactants and products. Formation Reactions: one mole of a compound is formed by elements at 1 atm and 25 C. E.g. Na(s) + ½Cl 2 (g) NaCl(s) Combustion Reactions: Organic compound with O 2 produce H 2 O and CO 2 E.g. 2C 4 H 10 (g) + 13O 2 (g) 8CO 2 (g) + 10H 2 O(g) Acid/Base (neutralization) reactions:an acid and a base react to form water and salt. E.g. H 2 SO 4 (acid ) + KOH (base) K 2 SO 4 (salt) + H 2 O (water) Precipitation Reactions: Two soluble salt solutions mixed to produce an insoluble salt. E.g. AgNO 3 (aq) + NaCl(aq) AgCl(s) insoluble salt + NaNO 3 (aq) Gas formation reaction: two chemicals react to produce a gas:co 2,SO 2(3), H 2 S,H 2,NH 3 E.g. Ca(CO) 3 (s) + HCl(aq) CaCl 2 (aq) + CO 2 (g) + H 2 O(l) Balancing Chemical Equations: 1.Check for formula of diatomic elements- H 2 - N 2 - O 2 - F 2 - Cl 2 - Br 2 - I 2; 2. Balance Metals; 3. Balance Nonmetals; 4. Balance Oxygen; 5. Balance Hydrogen; 6.Recount All Atoms; 7. Use groups of polyatomic ions if they didn t decompose as units. GHW#9 ey Questions (relatively simple to answer using the Focus Information) 1) Write chemical formulas for the following reaction with chemical names: Iron (II) Sulfide + Hydrochloric Acid --> Iron (II) Chloride + Hydrogen Sulfide 2) Given the chemical equation: 6 CO 2 (g) + 6 H 2 O (l) --> C 6 H 12 O 6 (s) + 6 O 2 (g); H = 2802 kj Interpret the information conveyed by the balanced chemical equation: a) Reactants: b) Products: Stoichiometric Coef. c) CO 2 : d) H 2 O: e) C 6 H 12 O 6 (s): f) O 2 : g) The sum:. Number of atoms on reactant side h) C =: i) H =: j) O =: k) C =:. Number of atoms on product side l) C =: m) H =: n) O =: o) C =:. p) Is the reaction balanced?. r) Reaction complete or equilibrium? s) Reaction endothermic or exothermic? s) Mole conversion factors: 3) Classify reactions based on simplicity/complexity of reactants/products a) 2Fe(s)+ 2O 2 (g) 2FeO(s): b)agno 3 (aq) + NaCl(aq) AgCl(s) + NaNO 3 (aq): c) Ca(OH) 2 (aq) + H 3 PO 4 (aq) Ca 3 (PO 4 ) 2 (aq) + H 2 O(l):

3 d) 2NaCl(s) 2Na(s) + Cl 2 (g): e) N 2 (g) + 3H 2 (g) 2NH 3 (g): f) Fe(s) + CuSO 4 (aq) FeSO 4 (aq) + Cu(s): g) 2P(s) + 3Cl 2 (g) 2PCl 3 (l): h) P 4 O 10 (s) + 6H 2 O(l) 4H 3 PO 4 (aq): i) 3Fe(s) + 4H 2 O(l) Fe 3 O 4 (s) + 4H 2 (g): j) 2H 3 PO 4 (aq) H 4 P 2 O 7 (s) + H 2 O(l): k) AgNO 3 (aq) + Cu(s) CuNO 3 (aq) + Ag(s): 4) Classify reactions based on type of reactants and products: C 2 H 6 (g) + O 2 (g) ---> CO 2 (g) + H 2 O(g): Ca(OH) 2 (aq) + H 3 PO 4 (aq) Ca 3 (PO 4 ) 2 (aq) + H 2 O(l): 2C 4 H 10 (g) + 13O 2 (g) 8CO 2 (g) + 10H 2 O(g): Na(s) + ½Cl 2 (g) NaCl(s): 2Na(s) + H 2 O(l) 2NaOH(aq) + H 2 (g): ½N 2 (g) + 3/2H 2 (g) NH 3 (g): HCl(aq) + FeS(s) FeCl 2 (aq) + H 2 S(g): P(s) + 3/2Cl 2 (g) PCl 3 (l): Al 2 (SO 4 ) 3 (aq) + 3Ca(OH) 2 (aq) 2Al(OH) 3 (s) + 3CaSO 4 (aq): CaC 2 (s) + 2H 2 O(l) C 2 H 2 (g) + Ca(OH) 2 (aq): 2As(s) + 6NaOH(aq) 2Na 3 AsO 3 (aq) + 3H 2 (g): 5) Predict the products of the following reactions: a) oxygen + hydrogen? b) chlorine + sodium iodide? c) calcium hydroxide + nitric Acid? 6) Write the chemical Equations and balance them: a) sodium hydroxide sodium oxide + water b) iron + oxygen iron (III) oxide c) carbon dioxide + water glucose + oxygen 7) Blance following reactions: a) MgO(s) + Si(s) Mg(s) + SiO 2 (s) First balance Metals (Mg and Si): MgO(s) + Si(s) Mg(s) + SiO 2 (s) Then balance Nonmetals(O): MgO(s) + Si(s) Mg(s) + SiO 2 (s) Reactant side: Mg, O, Si. Product side: Mg, O, Si.

4 MgO(s) + Si(s) Mg(s) + SiO 2 (s) b) P 4 O 10 (s) + H 2 O(l) H 3 PO 4 (l) First balance P and H: P 4 O 10 (s) + H 2 O(l) H 3 PO 4 (l) Then balance O: P 4 O 10 (s) + H 2 O(l) H 3 PO 4 (l) Reactant side: P, H, O. Product side: P, H, O. P 4 O 10 (s) + H 2 O(l) H 3 PO 4 (l) c) K 2 CO 3 (aq) + BaCl 2 (aq) = KCl(aq) + BaCO 3 (s) 2- Use groups of polyatomic ions if they didn t decompose as units i.e. CO 3 First balance K + and Ba +2 : K 2 CO 3 (aq) + BaCl 2 (aq) = KCl(aq) + BaCO 3 (s) Second balance Cl: K 2 CO 3 (aq) + BaCl 2 (aq) = KCl(aq) + BaCO 3 (s) Then balance CO 2 3 : K 2 CO 3 (aq) + BaCl 2 (aq) = KCl(aq) + BaCO 3 (s) Reactant side: K, Ba, CO 3, Cl. Product side: K, Ba, CO 3, Cl. K 2 CO 3 (aq) + BaCl 2 (aq) = KCl(aq) + BaCO 3 (s) d) NaOH(aq) + Al(NO 3 ) 3 (aq) = NaNO 3 (aq) + Al(OH) 3 (aq) Use groups of polyatomic ions if they didn t decompose as units i.e. NO - 3 and OH - First balance Na + and Al +3 : NaOH(aq)+ Al(NO 3 ) 3 (aq) = NaNO 3 (aq)+ Al(OH) 3 (aq) Second balance OH: NaOH(aq)+ Al(NO 3 ) 3 (aq) = NaNO 3 (aq)+ Al(OH) 3 (aq) Then balance NO 3 : NaOH(aq)+ Al(NO 3 ) 3 (aq) = NaNO 3 (aq)+ Al(OH) 3 (aq) Reactant side: Na, Al, NO 3, OH. Product side: Na, Al, NO 3, OH. NaOH(aq)+ Al(NO 3 ) 3 (aq) = NaNO 3 (aq)+ Al(OH) 3 (aq) e) Fe 2 (CO 3 ) 3 (s) + H 2 SO 4 (aq) = Fe 2 (SO 4 ) 3 (aq) + H 2 O(l) + CO 2 (g) Use groups of polyatomic ions if they didn t decompose as units i.e. SO not CO 3 First balance Fe +3 and H + : Fe 2 (CO 3 ) 3 (s) + H 2 SO 4 (aq) = Fe 2 (SO 4 ) 3 (aq) + H 2 O(l) + CO 2 (g) Second balance C: Fe 2 (CO 3 ) 3 (s) + H 2 SO 4 (aq) = Fe 2 (SO 4 ) 3 (aq) + H 2 O(l)+ CO 2 (g) Balance SO 2 4 : Fe 2 (CO 3 ) 3 (s) + H 2 SO 4 (aq) = Fe 2 (SO 4 ) 3 (aq) + H 2 O(l)+ CO 2 (g) Balance O: Fe 2 (CO 3 ) 3 (s) + H 2 SO 4 (aq) = Fe 2 (SO 4 ) 3 (aq) + H 2 O(l)+ CO 2 (g) Reactant side: Fe, H, SO 4, C, O. Product side: Fe, H, SO 4, C, O. Fe 2 (CO 3 ) 3 (s) + H 2 SO 4 (aq) = Fe 2 (SO 4 ) 3 (aq) + H 2 O(l)+ CO 2 (g)

5 f) C 3 H 8 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Balance C: C 3 H 8 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Balance H: C 3 H 8 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Balance O: C 3 H 8 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Reactant side: C, H, O. Product side: : C, H, O. C 3 H 8 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) g) C 4 H 10 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Balance C: C 4 H 10 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Balance H: C 4 H 10 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Balance O: C 4 H 10 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) use fractions!! Multiply by 2 remove fractions: C 4 H 10 (g) + O 2 (g) = CO 2 (g) + H 2 O(l) Reactant side: C, H, O. Product side: : C, H, O. C 4 H 10 (g) + O 2 (g) = CO 2 (g) + H 2 O(l)