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Ca(OH)2 + CO2 → CaCO3 + H2O
The reactants here are carbon dioxide and lime, the latter of which has been dissolved in water to make a solution. The products are water and calcium carbonate. The FACTSS letters that represent this reaction are C and S, because the reaction causes a precipitate to form, which also induces a color change. When the carbon dioxide gas is added to the lime, the lime slowly starts to turn a milky color that wasn't present before, as limewater is clear. The color change also shows that solid calcium carbonate has formed, which makes it a precipitate, as it's solid and a new substance. This is an example of chemical reaction because of a color change and the formation of a precipitate.

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2H2 + O2 → 2H2O
The reactants are hydrogen and oxygen. The product is water. Fire is used as a catalyst. When the two gases were heated in a container, they exploded the container. However, because of the explosion, the water molecules caused by the reaction became visible. Water was not a substance present at the start, so this was a chemical change. The FACTSS letter that applied was T, because a temperature change occured from the gases to the water that indicated a new substance had been created.

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Carbon dioxide (CO2) and Limewater (Ca(OH)2)

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Pb(NO3)2 + KI → PbI2 + 2KNO3
The reactants are lead nitrate and potassium iodide. The reactants are lead iodide and potassium nitrate. When the potassium iodide is dropped into the lead nitrate, which are both clear, a yellow substance pops up. The yellow substance is lead iodide, which is a new substance and precipitate, as it was not part of the reactants. Because the presence of the precipitate occured after the reactants were combined, it showed that a precipitate was evidence of a chemical change.

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NaCl + AgNO3 → AgCl + NaNO3
The reactants are table salt and silver nitrate. The products are silver chloride and sodium nitrate. Both the salt and silver nitrate were in the forms of clear solutions. So when they were combined, the white precipitate that appeared was very clearly a new substance. Neither of the reactants contained a white solid, so the presence of the new precipitate means that a chemical reaction occurred.

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2Na + Cl2 → 2NaCl
The reactants are sodium and chlorine, the latter of which is in a gaseous form. The product is table salt. When the sodium came into contact with the gas, a bright light started to emanate from the flask. And with such a sudden flash of bright light comes an influx of heat, which is a very evident temperature change. After the light clears, the heat remains, which is evidence that a new substance, table salt, had formed through the reaction.

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14KMnO4 + 4C3H5(OH)3 → 7K2CO3 + 7Mn2O3 + 5CO2 + 16H2O
The reactants are potassium permanganate and glycerin. The products are water, carbon dioxide, manganese oxide, and potassium carbonate.  When the glycerin is placed on the potassium permanganate, it immediately starts to steam and then combusts. Combustion means fire, and fire means an increase in heat. Fire also means that bonds are being broken and reformed, as always when substances get burned. Bonds being broken and reformed are also evidence of a chemical change, so the heat/change in temperature here shows that new substances were produced in a chemical reaction.

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4HNO3 + Cu → Cu(NO3)2 + 2NO2 + 2H2O
The reactants are copper and nitric acid. The products are copper nitrate, nitrogen dioxide, and water. When the nitric acid was poured over the copper, it produced a greenish blue substance. At the same time, a reddish brown cloud of nitrogen dioxide appeared. Neither of these colors were present at the start, so they indicate that a new substance was created through the reaction. The new colors show the presence of the newly created copper nitrate and nitrogen dioxide.

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Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
The reactants here are copper and silver nitrate. When the copper was inserted into the silver nitrate, it formed a new substance, copper nitrate. Copper nitrate is blue, and silver nitrate is clear, so there was a very obvious color change. And because the color change means a new substance, copper nitrate, was produced, it's an example of a chemical change.

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North Carolina School of Science and Mathematics

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Double Displacement Lead Nitrate and Potassium Iodide

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C12H22O11 + 12O2 → 12CO2 + 11H2O
The reactants are sugar and oxygen. The fire is used to speed up the process. The products are water and carbon dioxide. When the sugar is burned over fire, it produced a strong smell. The smell produced is indicative of a new gas being formed, which is carbon dioxide. Because the carbon dioxide was not present at the start, it means that it was a new substance produced by the reaction. The smell shows the presence of the gas, and is therefore an indicator that a chemical change has taken place.

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Na2S + 2HCl → 2NaCl + H2S
The reactants are sodium sulfide and hydrochloric acid. The products are salt and hydrogen sulfide. The solid sodium sulfide and liquid hydrochloric acid are mixed together, to form a really strong smell. The two substances smell on their own, but the hydrogen sulfide they produce, as a gas, smells very strong as well. Because gases cannot be seen, the smell is indicates that the new substance has been formed, which in this case is hydrogen sulfide. The hydrogen sulfide was not present at the start of the reaction, so it's a new substance.

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2H2O2 → 2H2O + O2
The reactant is hydrogen peroxide. The products are water and oxygen gas. Potassium iodide was used a catalyst to speed up the decomposition of the hydrogen peroxide. The reaction starts out with dish soap being added to the hydrogen peroxide. Then a solution of water and potassium iodide was added, to the mixture. The mixture then started to bubble and explode out. This is a representation of effervescence because of the oxygen that was produced, which is a new substance. Because of the dish soap, the oxygen was trapped and it was visible that a new gas had formed.

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NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2
The reactants are the baking soda and vinegar. The products are sodium acetate, water, and carbon dioxide. The reaction happening here shows the baking soda and water solution having vinegar added to it. When the vinegar is added, the solution starts to bubbles and fizz. This is a representation of effervescence because of the new gas being produced, and effervescence means a new gas is present as a result of the reaction. When the vinegar was added to the solution, it produced carbon dioxide gas, which was not present at the start of the reaction.

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North Carolina School of Science and Mathematics

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Double Displacement: Sodium Sulfide and HCl

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Hydrogen Peroxide and Potassium Iodide Reaction (Elephant Toothpaste)

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Fizz (Effervescence)

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Aroma

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Color

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Temperature

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New Substance

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Solid (Precipitate)