Chemical reactions can be detected fairly easily in chemistry. Three indicators of a chemical reaction are gas production, color change, and temperature change. In the mini lab we did today we set up a series of reactions each with separate indicators. In section one there was two reactions. Reaction one was when steel wool combines with oxygen. The balanced equation for that reaction is as shown 4Fe=3O2 —> Fe2O3. The second reaction in this section was with calcium oxide and water. My groups observations for this reaction was that it turned a milky white. When we added the Bromothymol blue indicator the solution turned blue indicating the solution was a base. The balanced equation is CaO+H2O—>Ca(OH)2. The reactions in this section were similar because they started with 2 reactants and then ended with just one. Section two consisted of two reactions also. Reaction 3 was the decomposition of hydrogen peroxide. The balanced equation was 2H2O2 (MnO2- catalyst)—> 2H2O+O2. Reaction four was decomposition of sodium hydrogen bicarbonate. The balanced equation is 2NaHCO3—> H2O=NaCO3+CO2. These two reactions started with one reactant and ended with two. Section three had two reactants as well. Reaction five was calcium and water. This reaction turned white and heated up. The BTB indicated it was a base because it stayed blue. The equation is CA+H2O—>H2+CA(OH)2. Reaction six was zinc and lead (II) nitrate: Zn+Pb(NO3)2—>Pb+Zn(NO3)2. These two reactions are similar because they went from element to compound both times. Section four had 3 parts. Reaction seven was sodium carbonate and barium nitrate: Na2(O3+Ba(NO3)2—>NaNO3+BaO3. Reaction eight was Lead (II) Nitrate and Potassium Iodide: Pb(NO3)2+2KI—>2KNO3+PbI2. Reaction nine: CACO3+@HCL—>CO2+H2O+CaCl2. These reactions all switch their reactants and precipitants around and that’s what they have in common. Section 5 has two reactions. Reaction ten: CH4+2O2—>CO2+2H2O. Reaction eleven: 4C2H5O2+9O2—>8CO2+10H2O. Section five are all combustion meaning their precipitants are always CO2 and H2O. You can tell these reactions are chemical reactions because each of them has at least one of the three indicators. Each section has a unique property, or set of reactants, precipitants, etc. Knowing this you can create a unique model for each reaction because it is predictable. Reactions can be predicted because they have set compounds or elements in the balanced equation. This means that you can predict the precipitant because you have to be able to balance your equation and use those compounds, so yes it is predictable.
Sources: Class experiment