Identifying equations 5 types

Combination or synthesis reaction

Always has multiple compounds on the left and a single compound on the right A + B  AB Examples: ◦2K + Cl 2  2KCl ◦S + O 2  SO 2

Decomposition reaction

Always has on compound on the left that breaks down into multiple things on the right AB  A + B Examples: ◦CaCO 3  CaO + CO 2 ◦2HgO  2Hg + O 2

Single replacement reaction

One element trades places with another element to form a new compound One element is always “dumped” A + BC  B + AC Single element + compound  single element + compound Examples: ◦Mg + Zn(NO 3 ) 2  Mg(NO 3 ) 2 + Zn ◦Mg + 2AgNO 3  Mg(NO 3 ) 2 + 2Ag

Double replacement reaction

Each compound “trades” an element ◦ polyatomic ions can act like a single element Compound + compound  Compound + compound AB + CD  AD + BC Examples: ◦Na 2 S + Cd(NO 3 ) 2  CdS + 2NaNO 3 ◦2NaCN + H 2 SO 4  Na 2 SO 4 + 2HCN

Activity series Sometimes elements will not react, depending on where they are on the activity series Mg + LiNO 3  no reaction Zn + HCl  H 2 + ZnCl 2 Cu + HCl  no reaction K + NaCl  Na + KCl Increasing reactivity Lithium Li Potassium K Calcium Ca Sodium Na Magnesium Mg Aluminum Al Zinc Zn Iron Fe Lead Pb (Hydrogen) (H)* Copper Cu Mercury Hg Silver Ag Decreasing reactivity

Combustion reaction

Element or compound reacts with oxygen to release energy. Hydrocarbon + oxygen  carbon dioxide + water Examples: ◦CH 4 + 2O 2  CO 2 + 2H 2 O ◦C 8 H 18 O O 2  8CO 2 + 9H 2 O