Double-Replacement RxnsDouble-Replacement Rxns• Two compounds are mixed

together and switch metal ions to form two new compounds as products.

• When the reaction works, a precipitate forms.

• Generic Equation:• AX + BY AY + BX

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Double-Replacement RxnsDouble-Replacement Rxns

AgNO3 (aq) + KCl (aq)

Ag+1 and Cl-1

K+1 and NO3-1

AgCl + KNO3

Equation is already balanced, but what states

are the products in?

Double-Replacement RxnsDouble-Replacement Rxns

• Must use solubility table to determine if either product will precipitate (solid!).

Nitrate (NO3-1) is in KNO3

Soluble, which means no precipitate.

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

Chloride (Cl-1) is in AgCl

Soluble, but Ag is an exception: precipitate!

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

Double-Replacement RxnsDouble-Replacement Rxns

Na2CO3 (aq) + AlCl3 (aq)

Al+3 and CO3+2

Na+1 and Cl-1

Al2CO3 + NaCl

Balance!!!

2 63

Now find the states of your products…..

Chloride (Cl-1) is in NaCl

Soluble, which means no precipitate.

Na2CO3 (aq) + AlCl3 (aq) Al2CO3 + NaCl2 63 (aq)

Carbonate (CO3-2) is in Al2CO3

Insoluble, (no exceptions) means precipitate!

Na2CO3 (aq) + AlCl3 (aq) Al2CO3 + NaCl2 63 (aq)(s)

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Combustion ReactionsCombustion Reactions

• A hydrocarbon is usually burned with Oxygen gas to produce Carbon Dioxide & Water.

• Example:

• CH4 + 2 O2 CO2 + 2 H2O