Chem 105 Chpt 4 Lsn 8Chem 105 Chpt 4 Lsn 8

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CHAPTER 4

Chemical Equations and Stoichiometry

Test 1 returnKnow elements 1-86 (symbol and spelling)Formulas must be balanced

neutral (i.e. charge of 0)Given table 3.1 (pg 107)

Test 1 returnKnow elements 1-86 (symbol and spelling)Formulas must be balanced

neutral (i.e. charge of 0)Given table 3.1 (pg 107)

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Balanced equationsBalanced equations(from neutral formulas)(from neutral formulas)

Conservation of matter (Lavoisier)Conservation of matter (Lavoisier)Stoichiometry (stoichiometric Stoichiometry (stoichiometric

coefficients)coefficients)Relationship between quantities prod. & Relationship between quantities prod. &

reactreact5 step process (pg 146)5 step process (pg 146)

Always start with neutral formulasAlways start with neutral formulas

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Conservation of Conservation of matter matter

(Lavoisier)(Lavoisier)

p.169b

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Balancing equationsBalancing equationsAluminum and bromine combine to Aluminum and bromine combine to

produce aluminum bromide. This is produce aluminum bromide. This is reacted with sulfuric acid (Hreacted with sulfuric acid (H22SOSO44). ). Hydrogen bromide (HBr) and Hydrogen bromide (HBr) and aluminum sulfate are produced. aluminum sulfate are produced.

1.) Write the formulas for the reactants 1.) Write the formulas for the reactants and products.and products.

2.) Balance the entire reaction.2.) Balance the entire reaction.

3.) Verify an equal number of atoms on 3.) Verify an equal number of atoms on reactant and product side.reactant and product side.

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Balancing an ionic equationBalancing an ionic equationNumber of atoms and charge must Number of atoms and charge must

be balanced.be balanced.Aluminum oxide (AlAluminum oxide (Al22OO33) and ) and

monatomic hydrogen gas combine to monatomic hydrogen gas combine to form water and aluminum ion.form water and aluminum ion.

Write formulas for balanced Write formulas for balanced reactants and products.reactants and products.

Balance the reaction. Balance the reaction. Double check.Double check.AlAl22OO3 3 + 6 H+ 6 H++ 2 Al 2 Al3+3+ + 3 H + 3 H22OO

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Balancing with a polyatomic ionBalancing with a polyatomic ion

Remember to keep the ion togetherRemember to keep the ion togetherPhosphoric acid (HPhosphoric acid (H33POPO44) and barium ) and barium

hydroxide combine to form barium hydroxide combine to form barium phosphate and water.phosphate and water.

Balance the starting material formulas Balance the starting material formulas and then the equationand then the equation

HH33POPO44 + Ba(OH) + Ba(OH)22 Ba Ba33(PO(PO44))2 2 + H+ H22OO

2H2H33POPO44 +3 Ba(OH) +3 Ba(OH)22 Ba Ba33(PO(PO44))2 2 +6 H+6 H22OO

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Mass relationships Mass relationships (use stoichiometric relation)(use stoichiometric relation)

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Mass relationshipsMass relationships

Fig. 4.8, p.159

NaNa22SOSO4 4 (aq)+ BaCl(aq)+ BaCl22 (aq) (aq) NaCl (aq) + BaSO NaCl (aq) + BaSO44 (s) (s)NaNa22SOSO4 4 (aq)+ BaCl(aq)+ BaCl22 (aq) (aq) NaCl (aq) + BaSO NaCl (aq) + BaSO44 (s) (s)

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Mass relationships Mass relationships NaNa22SOSO4 4 (aq)+ BaCl(aq)+ BaCl22 (aq) (aq) NaCl (aq) + NaCl (aq) +

BaSOBaSO44(s)(s)

Balance the equationBalance the equationHow many moles of NaCl will be produced How many moles of NaCl will be produced

from 0.81 moles of from 0.81 moles of NaNa22SOSO44??

How many grams of NaCl will be produced How many grams of NaCl will be produced from 0.81 moles of from 0.81 moles of NaNa22SOSO44??

How many grams of BaSOHow many grams of BaSO44 will be produced will be produced from 3.76 grams of BaClfrom 3.76 grams of BaCl22? ?

p.149

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Limiting reactant (reagent)Limiting reactant (reagent)

Which reactant is limiting?Which reactant is limiting?How much of product can be formed?How much of product can be formed?Ammonia gas can be prepared by the Ammonia gas can be prepared by the

reaction of a metal oxide such as reaction of a metal oxide such as calcium oxide with ammonium calcium oxide with ammonium chloride. If 112g of CaO and 224g of chloride. If 112g of CaO and 224g of NHNH44Cl are mixed, what mass of NHCl are mixed, what mass of NH33 can be produced?can be produced?

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Limiting reactant (reagent)Limiting reactant (reagent)

24. Aluminum chloride, AlCl24. Aluminum chloride, AlCl33, is made by , is made by treating scrap aluminum with chlorine.treating scrap aluminum with chlorine.

2 Al (s) + 3 Cl2 Al (s) + 3 Cl22 (g) (g) 2 AlCl 2 AlCl33 (s) (s)

If you begin with 2.70 g of Al & 4.05 g of If you begin with 2.70 g of Al & 4.05 g of ClCl22

a) Which reactant is limiting?a) Which reactant is limiting?

b) What mass of AlClb) What mass of AlCl33 can be produced? can be produced?c) What mass of the excess reactant c) What mass of the excess reactant

remains after the hexane has been remains after the hexane has been burned?burned?

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Next LessonNext Lesson

Percent yieldPercent yieldChemical equations and chemical Chemical equations and chemical

analysisanalysis

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p.162b

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Balancing Balancing EquationsEquationsBalancing Balancing EquationsEquations

____C____C33HH88(g) + _____ O(g) + _____ O22(g) ---->(g) ---->

_____CO_____CO22(g) + _____ H(g) + _____ H22O(g)O(g)

____B____B44HH1010(g) + _____ O(g) + _____ O22(g) ---->(g) ---->

___ B___ B22OO33(g) + _____ H(g) + _____ H22O(g)O(g)