Notes: Chemical Reactions

CHAPTER 11 NOTES: CHEMICAL REACTIONS

VOCABULARY:

Products what is formed in a chemical reaction; right of arrow Reactants what goes into a chemical reaction; left of arrow  yields + and (s) solid (l) liquid (g) gas (aq) aqueous – only works when dissolved in water Catalyst a substance that speeds up a reaction but is not itself consumed; provides an easier reaction pathway that requires less activation energy

Activation Energy (Ea) energy necessary to initiate a chemical reaction Δ heat

ENERGY OF CHEMICAL REACTIONS:

Exothermic Reaction: ΔH is – Endothermic Reaction: ΔH = + (heat is a “product”) (heat is a “reactant”)

Energy Energy

Time Time

BALANCED CHEMICAL REACTIONS

Law of Conservation of Matter: matter cannot be created or destroyed in a chemical reaction

WORD  FORMULA  BALANCED EQUATIONS

1. word equation: Hydrogen gas reacts with oxygen gas to form water

formula equation: ____ H2 + O2  H2O ______

diagram: H – H + O = O  O + O H – H H H H H

balanced reaction ____2 H2 + O2  2 H2O ______

2. word equation: Magnesium reacts with hydrochloric acid solution (HCl in water) to form magnesium chloride and hydrogen.

Formula equation: ____ Mg + HCl  MgCl2 + H2 ______

diagram: Mg + H – Cl  Cl-1Mg+2Cl-1 + H – H H – Cl

balanced reaction ______Mg + 2 HCl  MgCl2 + H2 ______

Try balancing these chemical reactions: a. 2 Na + H2SO4  Na2SO4 + H2

b. 2 K + Cl2  2 KCl

c. S8 + 8 O2  8 SO2

d. 3 F2 + 2 FeBr3  2 FeF3 + 3 Br2

e. 3 H2SO4 + 2 Al  Al2(SO4)3 + 3 H2

f. 2 NaNO3 + Ca(MnO4)2  2 NaMnO4 + Ca(NO3)2

g. C4H8 + 6 O2  4 CO2 + 4 H2O

h. 2 C2H6 + 7 O2  4 CO2 + 6 H2O

Balancing Chemical Equations

Balance the equations below:

1) ____ N2 + ____ H2  ____ NH3

2) ____ KClO3  ____ KCl + ____ O2

3) ____ NaCl + ____ F2  ____ NaF + ____ Cl2

4) ____ H2 + ____ O2  ____ H2O

5) ____ Pb(OH)2 + ____ HCl  ____ H2O + ____ PbCl2

6) ____ AlBr3 + ____ K2SO4  ____ KBr + ____ Al2(SO4)3

7) ____ CH4 + ____ O2  ____ CO2 + ____ H2O

8) ____ C3H8 + ____ O2  ____ CO2 + ____ H2O

9) ____ C8H18 + ____ O2  ____ CO2 + ____ H2O

10) ____ FeCl3 + ____ NaOH  ____ Fe(OH)3 + ____NaCl

11) ____ P + ____O2  ____P2O5

12) ____ Na + ____ H2O  ____ NaOH + ____H2

13) ____ Ag2O  ____ Ag + ____O2

14) ____ S8 + ____O2  ____ SO3

15) ____ CO2 + ____ H2O  ____ C6H12O6 + ____O2

16) ____ K + ____ MgBr  ____ KBr + ____ Mg

17) ____ HCl + ____ CaCO3  ____ CaCl2 + ____H2O + ____ CO2

18) ____ HNO3 + ____ NaHCO3  ____ NaNO3 + ____ H2O + ____ CO2

19) ____ H2O + ____ O2  ____ H2O2

20) ____ NaBr + ____ CaF2  ____ NaF + ____ CaBr2

ANSWERS:

1) 1 + 3  2 2) 2  2 + 3 3) 2 + 1  2 + 1 4) 2 + 1  2 5) 1 + 2  2 + 1 6) 2 + 3  6 + 1 7) 1 + 2  1 + 2 8) 1 + 5  3 + 4 9) 2 + 25  16 + 18 10) 1 + 3  1 + 3 11) 4 + 5  2 12) 2 + 2  2 + 1 13) 2  4 + 1 14) 1 + 12  8 15) 6 + 6  1 + 6 16) 2 + 1  2 + 1 17) 2 + 1  1 + 1 + 1 18) 1 + 1  1 + 1 + 1 19) 2 + 1  2 20) 2 + 1  2 + 1

SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

Types of Reactions: Synthesis (Combination), Decomposition and Combustion

Synthesis (Combination) – A + B  AB (1 product only)

Decomposition – AB  A + B (1 reactant only)

Combustion of a hydrocarbon – CxHy + O2  CO2 + H2O

Practice:

Balance each reaction below. Then identify the reaction type.

a. H2 + Br2  2 HBr __synthesis______

b. C4H8 + 6 O2  4 CO2 + 4 H2O __combustion______

c. 2 NaOH  Na2O + H2O __decomposition______

d. Ba(ClO3)2  BaCl2 + 3 O2 __decomposition______

First write and balance the equation. Then identify the reaction type. e. phosphorus + oxygen  tetraphosphorus decoxide __ synthesis ______

4 P + 5 O2  P4O10

f. pentane (C5H12) + oxygen  carbon dioxide + water __ combustion ______

C5H12 + 8 O2  5 CO2 + 6 H2O

g. magnesium chlorate  magnesium chloride + oxygen ___ decomposition ______

Mg(ClO3)2  MgCl2 + 3 O2

h. when solid calcium carbonate is heated calcium oxide and carbon dioxide are formed

___ decomposition ______CaCO3  CaO + CO2

i. the formation of calcium nitride from calcium and nitrogen ___ synthesis ______

3 Ca + N2  Ca3N2

j. sulfur trioxide mixes with water in the atmosphere to form sulfuric acid ___ synthesis ______

SO3 + H2O  H2SO4

NOTES: SINGLE REPLACEMENT REACTIONS & DOUBLE REPLACEMENT REACTIONS

1. Single Displacement Reactions (aqueous ONLY) metals: standard: A(s) + BX (aq)  AX (aq) + B(s)

example: Cu + 2 AgNO3  Cu(NO3)2 + 2 Ag

metal + acid: standard: A(s) + HX (aq)  AX (aq) + H2(g)

example: Mg + 2 HCl  MgCl2 + H2

metal + water: standard: A(s) + H2O(l)  AOH(aq) + H2(g)

example: 2 K + 2 H2O  2 KOH + H2

halogens: standard: X2 + AY  AX + Y2

example: F2 + 2 KI  2 KF + I2

2. Double Displacement (aqueous only) standard : AX (aq) + BY (aq)  AY(aq) + BX(s)

example : Ba(NO3)2 + NaI  BaI2 + NaNO3

3. Identify the reaction type for each reaction below. Then complete and balance the reaction.

_single displacement_ a. Ba + 2 AgNO3  Ba(NO3)2 + 2 Ag

__single displacement______b. F2 + 2 KI  2 KF + I2

__double displacement c. NaOH + CaCl2  2 NaCl + Ca(OH)2

___single displacement d. Zn + H2SO4  ZnSO4 + H2

WRITING WORD EQUATIONS

__decomposition______1. aluminum chlorate  aluminum chloride + oxygen 2 Al(ClO3)3  9 O2 + 2 AlCl3

__SR______2. lithium + iron (III) nitrate  lithium nitrate + iron 3 Li + Fe(NO3)3  3 LiNO3 + Fe

__decomposition______3. magnesium carbonate  magnesium oxide + carbon dioxide MgCO3  MgO + CO2

__synthesis______4. tin + nitrogen  tin (IV) nitride 3 Sn + 2 N2  Sn3N4

__SR______5. Zinc reacts with nitric acid to form zinc nitrate and hydrogen Zn + 2 HNO3  Zn(NO3)2 + H2

__decomposition______6. calcium hydroxide breaks down to form calcium oxide and water Ca(OH)2  CaO + H2O

WRITING WORD EQUATIONS WITH PREDICTING PRODUCTS

__synthesis______1. aluminum + oxygen  4 Al + 3 O2  2 Al2O3

__SR______2. sodium + silver nitrate  Na + AgNO3  NaNO3 + Ag

__SR______3. magnesium + hydrochloric acid  Mg + 2 HCl  MgCl2 + H2

___DR______4. solutions of iron (III) nitrate + potassium sulfate are mixed  2 Fe(NO3)3 + 3 K2SO4  Fe2(SO4)3 + 6 KNO3

____SR______5. Chlorine gas is bubbled through a solution of lithium iodide  Cl2 + 2 LiI  2 LiCl + I2

PREDICTING PRODUCTS

1) ____ Ag2SO4 + __2__ NaNO3  2 AgNO3 + Na2SO4

2) __2__ NaI + ____ CaSO4  CaI2 + Na2SO4

3) __2__ HNO3 + ____ Ca(OH)2  2 H2O + Ca(NO3)2

4) ____ Zn + ___2__ HNO3  Zn(NO3)2 + H2

5) ____ AlCl3 + ____ (NH4)3PO4  AlPO4 + 3 NH4Cl

6) ___3_ Pb + ___2_ Fe(NO3)3  3 Pb(NO3)2 + 2 Fe

7) ___2_ C3H6 + __9__ O2  6 CO2 + 6 H2O

8) ____ Ca + ____ Na2SO4  CaSO4 + 2 Na

PREDICTING PRODUCTS FOR THREE TYPES OF DECOMPOSITION REACTIONS:

 1. metal carbonate metal oxide + carbon dioxide

 example: sodium carbonate sodium oxide + carbon dioxide

 Na2CO3 Na2O + CO2

 Try: a. strontium carbonate ______strontium oxide + carbon dioxide______

____SrCO3  SrO + CO2______

 b. aluminum carbonate _____aluminum oxide + carbon dioxide______

____Al2(CO3)3  Al2O3 + 3 CO2______

 2. metal hydroxide metal oxide + water  example: sodium hydroxide sodium oxide + water

 2 NaOH Na O + H O 2 2

 Try: a. calcium hydroxide ______calcium oxide + water______

______Ca(OH)2  CaO + H2O______

 b. Iron(III) hydroxide ______iron (III) oxide + water______

______2 Fe(OH)3  Fe2O3 + 3 H2O______

 3. metal chlorate metal chloride + oxygen  example: sodium chlorate sodium chloride + oxygen



2 NaClO3 2 NaCl + 3 O2

 Try: a. barium chlorate _____barium chloride + oxygen______

______Ba(ClO3)2  BaCl2 + 3 O2______

 b. lithium chlorate ______lithium chloride + oxygen______

______2 LiClO3  2 LiCl + 3 O2______

KINETICS: RATE OF CHEMICAL REACTIONS

Collision Theory: for a reaction to occur, the reactants must collide with sufficient energy and with the proper orientation (and in the correct ratio)

Factors Affecting Reaction Rate:

1. Temperature

if temperature is increased, the reaction will be quicker. faster moving particles collide more often, and more particles will have enough energy (Ea) when they collide

2. Particle size (surface area)

more exposed particles causes more collisions, so there will be more collisions with the correct orientation

3. Concentration

Number of particles in a given volume affects rate of concentration – more particles, more collisions

4. Adding a Catalyst or Inhibitor

a catalyst speeds up a reaction by lowering the required activation energy an inhibitor slows down a reaction by raising the activation energy

WRITING WORD EQUATIONS a. lithium + nitrogen  lithium nitride

6 Li + N2  2 Li3N b. aluminum + oxygen  aluminum oxide

4 Al + 3 O2  2 Al2O3 c. sodium carbonate  sodium oxide + carbon dioxide

Na2CO3  Na2O + CO2 d. zinc + phosphoric acid  zinc phosphate + hydrogen gas

3 Zn + 2 H3PO4  Zn3(PO4)2 + 3 H2 e. chlorine gas + lithium iodide  lithium chloride + iodine

Cl2 + 2 LiI  2 LiCl + I2 f. sodium hydroxide  sodium oxide + water

2 NaOH  Na2O + H2O g. magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas

Mg + 2 HCl  MgCl2 + H2 h. solutions of iron (III) chloride and sodium hydroxide react to form iron (III) hydroxide and sodium chloride

FeCl3 + 3 NaOH  Fe(OH)3 + 3 NaCl i. when sodium is added to water, sodium hydroxide and hydrogen gas are produced\

2 Na + 2 H2O  2NaOH + H2 j. when zinc is placed in a solution of lead (II) nitrate, zinc nitrate and solid lead metal are formed

Zn + Pb(NO3)2  Zn(NO3)2 + Pb 13

SUMMARY - Predicting Products of Chemical Reactions Class of reaction Reactants Probable products Synthesis 2 or more substances 1 compound Decomposition 1 compound 2 or more elements and/or compounds Combustion Metal and oxygen Metal oxide Nonmetal and oxygen Nonmetal oxide Compound and oxygen 2 or more oxides Single Replacement Metal and a compound New compound and the replaced metal Nonmetal and a compound New compound and the replaced nonmetal Double Replacement 2 compounds 2 different compounds, 1 or which is either a precipitate, a gas, or water

Identifying Reaction Type Cheat Sheet Reaction Type Clue Synthesis 1 product Decomposition 1 reactant

Combustion CxHy + O2  CO2 + H2O Single Replacement element + compound  element + compound Double Replacement compound + compound  compound + compound