Steps to Predicting the Products of Chemical Reactions

Predicting products Here are a few important things to remember when predicting products: The compounds form must be neutral ionic compounds (which means you’ll be paying attention to their charges) You do NOT carry subscripts from the reactants to the products. You always balance your equation LAST

Diatomics! H, N, O, F, Cl, Br and I H2 N2 O2 F2 Cl2 , Br2 , I2 Remember the elements that exist in diatomic form. H, N, O, F, Cl, Br and I H2 N2 O2 F2 Cl2 , Br2 , I2

Once you classify the reaction, then write the products. If it is combustion, then just write H2O and CO2 as products. (remember to balance the equation). If it is synthesis, write a compound that contains both elements. (remember to balance the charges for ionic compounds) If it is decomposition, then attempt to break it into two elements or compounds.

If it is double replacement, then the cation and anions switch places. If it is single replacement, then replace the single element with the corresponding element in the compound. A metal will replace the cation in the compound A non-metal will replace the anion in the compound (Remember to take into account the charges on the cation and anion and write the formula correctly! If it is double replacement, then the cation and anions switch places. It is helpful to separate each compound into their cation and anionic parts with their charges. Then switch places, and crisscross the new compounds to make sure they are the correct neutral compound formulas.

Double Replacement Reactions Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq) Another example: K2SO4(aq) + Ba(NO3)2(aq)  2KNO3(aq) + BaSO4(s)

Now what? Once you write the molecular equation (synthesis, decomposition, etc.), you should check for reactants and products that are soluble or insoluble. We usually assume the reaction is in water We can use a solubility table to tell us what compounds dissolve in water. If the compound is insoluble (does NOT dissolve in water), then it remains as a compound If the compound is soluble (does dissolve in water), then splits the compound into its component ions

Solubility Table

Solubilities Not on the Table! Gases only slightly dissolve in water Strong acids and bases dissolve in water Hydrochloric (HCl), Hydrobromic (HBr), Hydroiodic (HI), Nitric (HNO3), Sulfuric (H2SO4), Perchloric (HClO4) Acids Group I (Alkali: Li, Na, K,…) hydroxides (should be on your chart anyway) Water slightly dissolves in water! (H+ and OH-) There are other tables and rules that cover more compounds than your table!

PREDICTING REACTION PRODUCTS: REPLACEMENT REACTIONS A metal will not always replace a metal in a compound dissolved in water because of differing reactivities An activity series can be used to predict if reactions will occur To replace a metal, the other metal must be MORE REACTIVE Same applies for halogens