The first demonstration was an example of combustion. The equation is CH3CH2OH + O2→ CO2 + H2O. When it is balanced, the equation is CH3CH2OH + 3O2→ 2CO2 + 3H2O. The catalyst in this equation was heat. CH3CH2OH is ethanol and O2 is oxygen.
Ms. Leland had been shaking ethanol in a 2-liter bottle to speed up its phase change into gas. She opened the cap and laid the bottle down on its side. Using a lighter, Ms. Leland put the flame to the tip of the bottle where the gas form of ethanol was. The bottle flew across the room with flame coming out of the bottle. A bit of the ethanol had dripped on the table, so there was even a flame on the table.
This the bottle flying across the room with a flame at its tip.
This is the leftover flame on the table.
The reason this reaction took place is because the products (CO2 + H2O) form covalent bonds, so when the catalyst was introduced to the gas form of ethanol, the atoms rearranged themselves. To meet the octet rule, it was easier for CO2 and H2O to share their atoms and become covalent. The flame was a result of the chemical reaction taking place. The reactants included a diatomic molecule (O2), and diatomic molecules tend to be stable, but they are more stable in a compound, so this is why O2 combined with carbon, so that it could be more stable.
The second demonstration was an example of acid base. The equation for this reaction is CH3COOH + NaHCO3→ H2O + NaOCOCH3 + CO2.
I predict that the gas produced will make the flame larger because CO2 and H2O will attract to make covalent bonds. In the previous demonstration when these elements were produced a large flame appeared.
Acetic Acid (vinegar) and Sodium Bicarbonate (baking soda) were the reactants. Together they formed bubbles and in these bubble is the gas, CO2, and when this gas was exposed to a candle, the flame instantaneously went out. This is because CO2 is not reactive with heat. Therefore, it did not react with the fire.
The flame went out as Ms. Leland poured CO2, a product of the combination of vinegar and baking soda, onto the flame.
The third demonstration was an example of single replacement. The equation for this reaction is HCl + Zn→ H + ZnCl. I predicted that the product would be ZnHCl because HCl (hydrochloric acid) is an ionic bond, so it is already together, and Zn (Zinc) is a Type II Cation. Therefore, it would go first.
I also predict that when a flame is introduced to the zinc and the HCl, the two will form a homogeneous mixture because zinc is not a strong metal, so it will dissolve quickly.
Ms. Leland added pieces of zinc to pure hydrochloric acid. The mixture began to bubble. When the flame was added a fire was on the solution, and it bubble up. The color changed to gray.
This is after Ms. Leland added fire to the mixture. There is flame also in the beaker on top of the mixture.
The reason that the color changed, and the beaker almost set on fire is because the gas form of pure hydrogen is extremely flammable. When zinc was added the ionic bond between HCl was broken. This freed up Cl, so it could bond with zinc. Therefore, the product of this reaction was H + ZnCl.
The final demonstration was an example of double displacement and synthesis. The equation is H2O2 + KI → H2O + O2 + KI. H2O2 is hydrogen peroxide, and KI is potassium iodide.
I predict that KI will stay the same because it stays the same in the equation. O2 will break off from H2O2 because it is a diatomic element, and diatomic elements are stable on their own.
This experiment was conducted three time before the desired result was produced.
In the first test 10 mL of KI was added to 40 mL of H2O2. The graduated cylinder basically threw up and emptied its contents on the ground. This could have happened because the chemicals were older, and they could have begun to decompose.
In the second experiment, the KI and H2O2 mixture turned brown and bubbled up. There was a lot of gas coming out of the cylinder.
In the third experiment, dish soap was added. Dish soap will trap the gas, but it will still bubble up because hydrogen peroxide is still mixing with potassium iodide. When the soap was added, it did trap the gas, and the mixture kept flowing out of the cylinder. This is also known as elephant toothpaste.
This is the mixture flowing out of the cylinder.
In conclusion, the experiments performed today helped me understand the different types of chemical reactions. They were very interesting and cool! It was fun to see the different products. My favorite was the combustion demonstration because it was fascinating to learn why the bottle flew across the room! :)
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