Combustion, a type of chemical reaction. Also, my picture.

Combustion, a type of chemical reaction. Also, my picture.

This lab was actually one giant lab made out of 11 smaller labs, whose objective was to show us the various types of chemical reactions that can happen. Here are the balanced chemical equations for those 11 labs:

1. 4Fe(s) + 3O2(g) –> 2Fe2O3(s)

2. CaO(s) + H2O(l) –> Ca(OH)2(aq)

3. 2H2O2(l) —MnO2–> 2H2O(l) + O2(g)

4. 2NaHCO3(s) –> H2O(l) + Na2CO3(s) + CO2(g)

5. Ca(s) + 2H2O –> H2(g) + Ca(OH)2(aq)

6. Zn(s) + Pb(NO3)2(aq) –> Pb(s) + Zn(NO3)2(aq)

7. Na2CO3(aq) + Ba(NO3)2(aq) –> 2NaNO3(aq) + BaCO3(s)

8. Pb(NO3)2(aq) + 2KI(aq) –> 2KNO3(aq) + PbI2(s)

9. CaCO3(s) + 2HCl(aq) –> CO2(g) + H2O(l) + CaCl2(aq)

10. CH4(g) + 2O2(g) –> CO2(g) + 2H2O(g)

11. 4C2H5O2(l) + 9O2(g) –> 8CO2(g) + 10H2O(g)

But so all of those equations above were not painstakingly written in vain, how do we know for certain that they are actually chemical reactions? Well, there are three major indicators: a color change, the appearance of bubbles or fizzing, and a precipitate forms. And, at least one of each was seen during each minilab.For example, my partner and I observed bubbles appear during our first minilab (#3), which meant a gas was being produced that wasn’t already there. During our second minilab (#11), we burned ethanol and watched the liquid’s color change from clear to a brilliant blueish flame as it combusted (which is also another indicator of a chemical reaction).

My picture

My picture; bubbles are the tiny and fuzzy dots

Furthermore, the reactions were divided up into five sections: Section 1 (1, 2); Section 2 (3, 4); Section 3 (5, 6); Section 4 (7, 8, 9); and Section 5 (10, 11). This was done based on similarity, which is so reliable that I can even show simple, general example reactions, too:

Section 1: Two reactants that produced one product.  Ex: AB + C –> ABC
Section 2: One reactant that produced two or more products.  Ex: ABC –> AB + C
Section 3: One element or ion is replaced by another element/ion in a compound.  Ex:  A + BC –> AB + C
Section 4: Two compounds exchanged their elements/ions for those of the other compound.  Ex: AB + CD –> AD + CB
Section 5: Combustion, which usually results in only water and carbon dioxide.  Ex: CxHyOz + O2 –> CO2 + H2O

From those examples above,  I’m pretty certain that the products of reactions can be predicted because the reactants can just be plugged into one of the example reactions and a product(s) can be predicted based on the reactants’ ions, charge, and otherwise chemical composition.

Advertisements