Chemical Reactions CHM 1010 PGCC Barbara Gage

Chemical Reactions

CHM 1010 PGCC Barbara Gagehttp://www.reviseguys.com/moodle/course/view.php?id=10

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Chemical Reaction

• Chemical change = chemical reaction

Changes may be visible: • color change• cloudiness (precipitation)• gas formed (bubbles and/or odor)• reactant decreases (without dissolving)• energy is released or absorbed

CHM 1010 PGCC Barbara Gage

Chemical Equations

• Chemical changes can be written symbolically. The symbolic representation is called a chemical equation.

Carbon reacts with oxygen to form carbon dioxide.

C + O2 CO2

reactants products


Chemical Equations

• Reaction arrows can go in either direction:

2 H2 + O2 2 H2O

• Or both directions:NH4OH NH3 + H2O



Or…

Chemical Equations

• Because of the Law of Conservation of Matter, you must account for all atoms in a chemical change.

Carbon reacts with oxygen to form carbon monoxide.

C + O2 CO

2 C + O2 2 CO


coefficientEquation is now balanced.

Chemical Equations

• A sample of propane, C3H8, when ignited with oxygen produces carbon dioxide and water.

C3H8 + O2 CO2 + H2O

C3H8 + 5 O2 3 CO2 + 4 H2O


Chemical Reactions

Al + O2 Al2O3

CaCO3 + HI CaI2 + CO2 + H2O

Na3PO4 + BaCl2 NaCl + Ba3(PO4)2

C4H10 + O2 CO2 + H2O


Chemical Equations

• If you have information on the states of matter, that can be added to the equation.

s = solid l = liquid g = gas aq = aqueous

Aqueous silver nitrate reacts with aqueous potassium chloride to form solid silver chloride and aqueous potassium nitrate.

AgNO3 (aq) + KCl (aq) AgCl (s) + KNO3 (aq)


Balancing Tips…

• Balance polyatomic ions that stay intact as a single unit.

• Leave hydrogens and oxygens to the last (oxygen very last)

• Be sure to reduce the coefficients to the smallest whole numbers.


• Write the balanced chemical equation for the change in the boxes and indicate the reaction type.


Before

After

Let’s look at the lab rxns…

• Mg (s) + HCl (aq) -------> • CuCO3 (s) ----------> • Mg (s) + ------------->

• NaHCO3 (s) + HCl (aq)-----> • CuSO4 (aq) + Fe (s) -------->


Let’s look at the lab rxns…

• CoCl2 (aq) + Na3PO4 (aq) –>

• KClO3 (s) + --------->

• Fe (s) + ---------->

• HCl (aq) + NaOH (aq) ---->


• Mg (s) + 2 HCl (aq) -------> MgCl2 (aq) + H2 (g) • CuCO3 (s) + -------------> CuO (s) + CO2 (g) • 2Mg (s) + O2 (g) -------------> 2MgO (s) • NaHCO3 (s) + HCl (aq)---> NaCl (aq) + H2CO3 (aq) ---->

NaCl (aq) + H2O (l) + CO2 (g)

• CuSO4 (aq) + Fe (s) --------> Cu (s) + FeSO4 (aq) • 3CoCl2(aq) + 2Na3PO4(aq) –>Co3(PO4)2(s) + 6NaCl (aq) • 2KClO3 (s) + -----------------> 2 KCl (s) + 3 O2 (g) • 2Fe (s) + O2 (g) ---------------> 2 FeO (s) • HCl (aq) + NaOH (aq) ----> NaCl (aq) + H2O (l)


Types of Reactions

• 1) Combination or Synthesis

• elements or (element + compound) or compounds ------> compound

• Fe (s) + S (s) ------>FeS (s)

• O2 (g) + 2 CO (g) ------> 2 CO2 (g)

• H2O (l) + SO3 (g) ------> H2SO4 (aq)






Types of Reactions

• 2) Decomposition or Analysis • compound ------> elements or (element

and compound) or compounds

• 2 HgO (s) -----> 2Hg (l) + O2 (g)

• 2 KBrO3 (s) -----> 2 KBr (s) + 3 O2 (g)

• CaCO3 (s) ------> CaO (s) + CO2 (g)






Types of Reactions

• 3) Single Replacement

• element + compound --------> element + compound

• Cu (s) + 2AgNO3 (aq) ---->2Ag (s) + Cu(NO3)2 (aq)



•Mg (s) + 2 HCl (aq) -------> MgCl2 (aq) + H2 (g)

•CuCO3 (s) + -------------> CuO (s) + CO2 (g)

•2Mg (s) + O2 (g) -------------> 2MgO (s)

•NaHCO3 (s) + HCl (aq)---> NaCl (aq) + H2CO3 (aq) ----> NaCl (aq) + H2O (l) + CO2 (g)

•CuSO4 (aq) + Fe (s) --------> Cu (s) + FeSO4 (aq)

•3CoCl2(aq) + 2Na3PO4(aq) –>Co3(PO4)2(s) + 6NaCl (aq)

•2KClO3 (s) + -----------------> 2 KCl (s) + 3 O2 (g)

•2Fe (s) + O2 (g) ---------------> 2 FeO (s)

•HCl (aq) + NaOH (aq) ----> NaCl (aq) + H2O (l)

Types of Reactions• 4) Double Replacement

compound + compound —> compound +compoundAgNO3 (aq) + NaCl (aq) —> AgCl (s) +NaNO3 (aq)

• Double Replacement Rxns:

Solid formingAgNO3 (aq) + NaCl (aq) —> AgCl (s) +NaNO3 (aq)

Gas-forming

KHCO3 (aq) + HCl (aq) ----> KCl (aq) + CO2 (g) +H2O (l)

Acid-BaseHCl (aq) + KOH (aq) ----> KCl (aq) + H2O (l)



•Mg (s) + 2 HCl (aq) -------> MgCl2 (aq) + H2 (g)

•CuCO3 (s) + -------------> CuO (s) + CO2 (g)

•2Mg (s) + O2 (g) -------------> 2MgO (s)

•NaHCO3 (s) + HCl (aq)---> NaCl (aq) + H2CO3 (aq) ----> NaCl (aq) + H2O (l) + CO2 (g)

•CuSO4 (aq) + Fe (s) --------> Cu (s) + FeSO4 (aq)

•3CoCl2(aq) + 2Na3PO4(aq) –>Co3(PO4)2(s) + 6NaCl (aq)

•2KClO3 (s) + -----------------> 2 KCl (s) + 3 O2 (g)

•2Fe (s) + O2 (g) ---------------> 2 FeO (s)

•HCl (aq) + NaOH (aq) ----> NaCl (aq) + H2O (l)

Types of Reactions

• 5) Oxidation-Reduction (redox)CH4 (g) + 2O2 (g) ----> CO2 (g) + 2H2O (l)

2Mg (s) + O2 (g) -----------> 2MgO (s)

4HCl (aq) + 3FeCl2 (aq) + KMnO4(aq) --> MnO2(s) + KCl(aq) + 3FeCl3(aq) + 2H2O(l)



Mg (s) + 2 HCl (aq) -------> MgCl2 (aq) + H2 (g) CuCO3 (s) + -------------> CuO (s) + CO2 (g) 2Mg (s) + O2 (g) -------------> 2MgO (s) NaHCO3 (s) + HCl (aq)---> NaCl (aq) + H2CO3 (aq) ---->


CuSO4 (aq) + Fe (s) --------> Cu (s) + FeSO4 (aq) 3CoCl2(aq) + 2Na3PO4(aq) –>Co3(PO4)2(s) + 6NaCl (aq) 2KClO3 (s) + -----------------> 2 KCl (s) + 3 O2 (g) 2Fe (s) + O2 (g) ---------------> 2 FeO (s) HCl (aq) + NaOH (aq) ----> NaCl (aq) + H2O (l)

Solubility Rules

• Reactants and products of reactions may be soluble.

• Use solubility rules to label them.


Solubility RulesSoluble Ionic Compounds• All common compounds of Group IA (1) ions and ammonium ion are

soluble.• All common nitrates, acetates, and most perchlorates are soluble.• All common chlorides, bromides, and iodides are soluble, except for

those of silver (I), lead (II), copper (I) and mercury (I). All common fluorides are soluble except those of lead (II) and Group IIA (2).

• All common sulfates are soluble except those of calcium, strontium, barium, silver (I), and lead (II).

Insoluble Ionic Compounds• All common metal hydroxides are insoluble, except those of Group

IA (1) and the larger members of Group IIA (2) (beginning with calcium).

• All carbonates and phosphates are insoluble, except those of Group IA (1) and ammonium ion.

• Most other combinations not mentioned above (such as chromates, oxides, sulfides) are insoluble, except those of Group IA (1) and ammonium ion. CHM 1010 PGCC Barbara

Gage

Predicting Reactions…

• Complete and balance the following: copper(II) chloride reacts with sodium

hydroxide

• CuCl2 (aq) + NaOH (aq)

• Double displacement reaction…CuCl2 (aq) + NaOH (aq) Cu(OH)2 + NaCl

• CuCl2 (aq) + 2 NaOH (aq) Cu(OH)2 (s) + 2 NaCl (aq)


Ionic reactions

• Ionic compounds in solution dissociate into ions.

• CuCl2 (aq) + 2 NaOH (aq) Cu(OH)2 (s) +

2 NaCl (aq)Is actually…• Cu2+ (aq) + 2 Cl- (aq) + 2 Na+ (aq) + 2 OH-

(aq) Cu(OH)2 (s) + 2 Na+ (aq) + 2 Cl- (aq)


Net Ionic Reactions

• Cu2+ (aq) + 2 Cl- (aq) + 2 Na+ (aq) + 2 OH-

(aq) Cu(OH)2 (s) + 2 Na+ (aq) + 2 Cl- (aq)

• Cu2+ (aq) + 2 Cl- (aq) + 2 Na+ (aq) + 2 OH- (aq) Cu(OH)2 (s) + 2 Na+ (aq) + 2 Cl- (aq)

• Cu2+ (aq) + 2 OH- (aq) Cu(OH)2 (s)

net ionic equation


Net Ionic Reactions• Lead (II) nitrate reacts with potassium iodide• Pb(NO3)2 + KI • Pb(NO3)2 + KI PbI2 + KNO3

• Pb(NO3)2 (aq) + 2 KI (aq) PbI2 (s) + 2 KNO3 (aq)

• Pb2+ (aq) + 2 NO3- (aq) + 2 K+ (aq) + 2 I- PbI2 (s) +

2 K+ (aq) + 2 NO3- (aq)

• Pb2+ (aq) + 2 NO3- (aq) + 2 K+ (aq) + 2 I- PbI2 (s) +

2 K+ (aq) + 2 NO3- (aq)

• Pb2+ (aq) + 2 I-(aq) PbI2 (s)net ionic equation


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Chemical Reactions CHM 1010 PGCC Barbara Gage