p1g4+mp4





What are some signs that a chemical reaction is taking place?

Signs of a chemical reaction Combination of chemicals 10 mL of a liquid .5g of a substance
 * **__ Combination __** ||  **__ Prediction __**  ||  **__ Observation __**  ||
 * H2O + CHNaO3 || The sodium bicarbonate will form a suspension || _ ||
 * CaCl2+ CHNaO3 || The sodium bicarbonate will dissolve || _ ||
 * CaCl2+ H2O || The substance will remain the same. The temperature of the substance will rise as CaCl2 dissolves and exerts energy in the form of heat ||  ||
 * CHNaO3+ CaCl2+ H2O || The CaCl2 will dissolve into the CHNaO3 ||  ||
 * BB+ Cacl2 || The BB will turn yellow as the CaCl2 is added ||  ||
 * BB+CHNaO3 || Color change ||  ||
 * BB+CHNaO3+Cacl2(+H2O) || Color change and gas will form ||  ||

- Water

H2O

No smell

No taste

PH value of 7

Non-flammable

- CaCl2- Calcium Chloride (ionic compound)

De-icing agent

Used on sidewalks

Used in fire extinguishers

Non-flammable

Non-toxic

Does not burn

Reacts with Zinc and Sodium

Do not ingest

Dissolves exothermically

Releases heat when it dissolves (melts ice)

- Sodium Bicarbonate

CHNaO3

Treats heartburn and upset stomachs

Cleaner

Baking Soda

Cooking additive

Used in toothpaste

Non-toxic

Non-flammable

Non-corrosive

Non-explosive

- Bromothymol Blue

Indicator in acidic, neutral, and alkaline solutions

C27H27Br2O5SNa

Irritates eyes

Slight skin irritation

Non-explosive

Non-flammable





|| 23.2  ||  1.6  || ||  20.3  ||  23.9  ||  3.6  ||
 * __ Combination __ ||  __ Start Temp (oC) __  ||  __ End Temp (oC) __  ||  __ Change __  ||
 * BB+ CaCl2 [[image:mrslagunasclass/H2O_and_CaCl2.jpg width="160" height="70"]] ||
 * CHNaO3+ CaCl2 ||  21.8  ||  21.8  ||  0  ||
 * BB+ H2O+ CHNaO3 ||  19.2  ||  18.8  ||  -.4  ||
 * CaCl2+ H2O
 * CHNaO3­+ CaCl2+ H2O ||  20.3  ||  20.2  ||  -.1  ||
 * CHNaO3+ CaCl2+ BB (H2O) ||  20.0  ||  20.6  ||  .6  ||



Some signs of a chemical reaction taking place is an odor, a color change, and a gas being formed. During our lab, our independent variables and dependent variables were very dependent on each other, the independent variable being the combination of chemicals in the test tube and the dependent variable being the sign of a chemical reaction. In our experiment, with each different combinations of chemicals the sign of a chemical reaction it produced was different. For example, the combination of Bromothymol Blue and Calcium Chloride had started to bubble proving that a gas was formed, which is a chemical reaction. Sodium Bicarbonate and Calcium Chloride, though, had no chemical reaction whatsoever. All our results had varied a little, but a lot of the chemical reactions ended up being a gas forming (shown through bubbling) or not reacting at all.



Some of our hypotheses were supported depending on which combination of chemicals. The one which were supported (or partly supported) are the combinations of bromothymol blue and calcium chloride and sodium bicarbonate, calcium chloride, and water. The rest of the hypotheses for the 6 remaining combinations were disproved. Our table shows that our results were similar to our predictions. For example, bromothymol blue and calcium chloride we predicted that a gas would be formed. Also, for sodium bicarbonate, calcium chloride, and water we predicted a gas formation. But, for a combination like sodium bicarbonate and calcium chloride we predicted that an odor would be produced but __no__ chemical reaction at all occurred. In our lab we did not use a graph.



How does the mass of the reactants compare to the mass of the products in a chemical reaction, when a precipitate is formed? The mass will remain the same when the precipitate is formed.



Mass of the reactant



Mass of the product



Lead Nitrate - Pb(No3)2

Sodium Iodide - NaI



- Lead Nitrate: toxic, lead poisoning, it can't be inhaled or digested, inorganic compound, crystal form

- Sodium Iodine: Ionic, crystalline salt, used in radiation detection, used to help and treat iodine deficiency, soluble

- Sodium Nitrate (product): chemical compound, used in fertilizers, smoke bombs, pottery enamels, and food preservatives,

First we found the mass of the glassware, then we found the mass of the reactants and the glassware, the mass of the reactants alone came next, next was the products of the reactants and the glassware, the products alone were next, and lastly we measured the change in mass. In the end, we found that the mass did not change and it produced a yellow pigment.

toc


 * Group Number ||  Mass of the Glassware  ||  Mass of the Reactants and Glassware  ||  Mass of the Reactants Alone  ||  Mass of the Products and Glassware  ||  Mass of the Products Alone  ||  Change in Mass  ||
 * 4 ||  82.2  ||  86.4  ||  4.2  ||  86.4  ||  4.2  ||  0  ||

Sodium Iodide + Lead Nitrate --> Sodium Nitrate + Lead Iodide

This is a double-replacement reaction

Pb(NO3)2 + 2NaI --> 2NaNO3 + PbI2



Observations after filtering: - There was a yellow residue - There was a clear filtrate The yellow residue was the newly formed lead iodide. During the double replacement reaction, a solid yellow substance used in paints was formed. This was the lead iodide. When we filtered our new substance, a yellow residue was left in the filter paper. The clear substance that filtered through the paper (also called the filtrate) was called sodium nitrate. Sodium nitrate is used in smoke bombs and pottery enamel.

The question we were trying to answer in this lab was how the mass of the reactants compare to the mass of the products in a chemical reaction, when a precipitate is formed. We discovered that the mass does not change because there was not a precipitate formed. When we combined lead nitrate with sodium iodide; which then formed a new substance that was yellow. This substance was lead iodide and sodium nitrate.