# Calibration of a pH Spectrum

Today, May 11, in Mr. Wong’s Chemistry class, my lab group conducted an experiment where we were able to find the different pH values of solutions to create a spectrum. First, we created the full spectrum by using cabbage juice as the solvent in our solutions. We began by putting drops of acid into the cabbage juice to decrease the pH by about 1 each time by using a pH probe. Next we used a different solution with cabbage juice and put drops of a base in it to raise the pH by 1 each time. By taking a sample for each pH, we were able to make a full spectrum representing various pHs. The change in the pH of each solution also alters the color of each solution. The colors at one end (the bases) start dark blue and then become a lighter green. As the spectrum continues, it turns into a light pink and then to a dark purple (the acids). The spectrum represents the change in color, hydrogen ions, and pH.

Here are our tables:

Here are the corresponding graphs:

# Pressure In Popcorn

On last Friday in Mr. Wong’s Chemistry class, my lab group conducted an experiment to find the pressure within popcorn kernals.  To do this, we first needed to get the measurements of the popcorn kernals before they were popped as well as after they popped. We first found the number of kernals that we were going to use and found the volume. Next, we combined oil and the kernals in the beaker and recorded the weight. After taking those measurements of initial volume and mass, we conducted the experiemnt to find the new volume and mass. We then determined the number of kernals that popped from our original 42 and were able to find the correct volume and mass. We also were able to find the temperature  of 498 K. Lastly we used PV=nRT to find the pressure required to burst a kernal of popcorn.

Our Popcorn heating and popping:

Our popped popcorn:

Our Table:

Our work:

Analysis Questions:

1.  9.8-5.0 = 4.8ml of popcorn kernals = 0.0048L of Popcorn Kernals
2. 131.8g – 122.5g = 9.3g of water vapor released
3. 9.3g of H20/18g of H20 = 0.52 mol of H20
4. Works shown above: 13.01 atm
5. The difference between the atmospheric pressure to the pressure of water vapor in the kernal is that the atm pressure is used to pop the kernal and the water vapor pressure is what gets popped as the pressure inside the kernal.
6. I think that all of the popcorn kernals did not pop because each kernal had a different pressure within it and therefore different atm pressure was required to pop each one.
7. There could have possibly been burnt leftovers in our beaker when we started the experiment which could have led to a mass error. This could be fixed by completely cleaning ou the beaker.

# Limiting Reagent Lab Activity

In Mr. Wong’s Chemistry class on Friday, my lab group and I participated in a limiting reactions Lab where we mixed different reactants in a flask and had the products from that reaction fill up a balloon. In this experiment we combined acetic acid with sodium bicarbonate to get sodium acetate, carbon dioxide, and water. It was a fun, exciting, and interactive activity which taught me the role of limiting reagents in chemical reactions. Below is the work on our lab. Enjoy.
CH3COOH + NaHCO3 –> NaCH3COO + CO2 + H2O

In our experiment, the green ballon contained 4 grams of sodium bicarbonate. The white ballon contained 2.5 grams of sodium bicarbonate. The blue balloon contained 1 gram of sodium bicarbonate.

Our Table:

 Balloon Color Amount of Sodium Bicarbonate (g) Amount of Acetic Acid (mL) Circumference of Balloon (cm) Amount of Gas Produced (cm^3) Blue 1 50 16.51 76.16 White 2.5 50 29.21 420.95 Green 4 50 35.56 759.1

Analysis:

1. What are the limiting and excess reagents for each flask? How did you determine this?   The excess reagents for each flask with 1 and 2.5 grams of sodium bicarbonate is the acetic acid. Therefore, the limiting reagent in those two experiments would be the sodium bicarbonate. However, in the experiment with 4 grams of sodium bicarbonate, the limited reagent is the vinegar and the excess is the sodium bicarbonate. I deterined this because I understood that the variable that was changed was the sodium bicarbonate. The more sodium bicarbonate added to each experiement, the more the balloon was filled. Because of this, the unchanged acetic acid in each experiment was sometimes the limiting reagent because there was some left over to make the reaction.
2. How is the amount of product in a reaction affected by an insufficient quantity of any of the reactants (reagents)?   The amount of product in a reaction is affected because the quantity of the reactants will change the outcome and amount the products have.
3. Which balloon was the largest? Explain.  The balloon with 4 grams of sodium bicarbonate was the largest balloon because it reacted with the acetic acid to make a lot of carbon dioxide which filled up the balloon.
4. Which balloon was the smallest? Explain.   The smallest balloon was the one with only one gram of sodium bicarbonate. This created less carbondioxide and therefore inflated the balloon less.
5. Rust is produced when iron reacts with oxygen. How many grams of Fe2O3 are produced when 12.0 g of iron rusts?4Fe(s) + 3O2(g) → 2Fe2O3(s)  17.2 grams on Fe2O3.
6. What real-life applications can this concept of limiting and excess reagents be applied to?  The real life applications that this concept of limiting and excess reagents can be applied to could be knowing the products and outcomes of a reaction and how much of on substance will be excess or limiting.

# My Penny Battery

My Construction of the Battery:

• First, I cleaned my pennies by putting them in vinegar and salt.
• Then, I cut out a few circles of cardboard the same size as the pennies.
• Next, I soaked them in Vinegar.
• Later, I cut out a few circles of foil that were  once again the same size as the pennies.
• Finally, I put all of these together. Penny, then cardboard ,then foil. I repeated this several times.

I was able to produce a light on my LED.

I tested my penny battery with the voltmeter and had a charge of 4.02.

The Electrolytes Present in this Experiment:

• Sodium
• Chlorine
• Potassium

My experiment was finally successful because I was able to contruct a battery out of pennies different than the one made in class. I was also able to light up the LED that I attatched my battery to. I also checked my voltmeter that I had at home and learned how to use it. I think that the connection of the four pieces together was key and that was what made the battery have power. The thin cardboard, pennies, vinegar, and foil were the components which gave the battery power. I also learned through trial and error with this contruction of the penny. I now understand that the specific way in which I put the order of pennies, thin cardboard, and foil effect whether the battery will work or not. The battery was a good source of energy because of all the electrolytes that make it up. Overall, I learned how to make a battery out of pennies and other materials to produce conductivity.

# Electrolytes In My Refrigerator!!!!

I was feeling extremely hungry one afternoon and I opened my fridge to see if there was anything to eat or drink.  As I looked around, I thought about how Mr. Wong taught us about electrolytes and how they were around us all the time in our daily life. I began identifying all the electrolytes in my refrigerator.

Electrolytes:

– Sodium, Calcium, Potassium, and Magnesium.

Spinach:

–

– Magnesium, calcium, potassium, and iron.

Potatoes:

– potassium, calcium, magnesium, phosphorus, iron, and zinc.

Milk, Cheese, yogurt, or any Dairy Product:

– Calcium, sodium, chloride, potassium, and magnesium.

Lettuce, olives, celery, and tomato:

– chloride

Bananas:

-Potassium

Eggs:

-iodine

Rasins:

– magnesium, calcium, and potassium, as well as iron, zinc, manganese, and fluoride,

# Penny Batteries, Electrolytes, and Conductivity

Contructing the battery and our materials:

Our Final Product:

Our Voltmeter Test:

Our electrolytes that were present:

• Sodium
• Chlorine
• Potassium

Our experiment was unsuccessful because our battery did not light up the LED bulb. When we checked the voltage of the battery with the voltmeter, there was energy just not enough to light the LED light. I think that the metal of the copper and zinc connected through the wet matboard was able to conduct the power to light the bulb. I think that the alternating sequence between the zinc, matboard, and copper was ideal for conducting electricity and therefore working as a battery. Also, because the Matboard pieces were dipped in the solution with the water, salt, and vinegar. The specific way in which the battery was constructed and made, would make it ideal for conducting energy as long as the zinc or copper did not touch one another. The battery should be able to conduct because of the electrolytes that were present in it’s pieces that made it up.

# Reactivity of Metals

Solution before lithium exposure.

Solution before lithium exposure

Solution before sodium exposure

Solution after sodium exposure

Solution before calcium exposure

Solution during calcium exposure

Solution after calcium solution

Solutions after magnesium exposure (left) and aluminum exposure (right)

Vinegar and pH indicator solution

After completing this lab, I realized that many of the metals have different reactions and take different amounts of time to begin to change. Many of these elements contain different properties that signify why they react the way they do. The periodic table is arranged in such a way to represent the reactions of these different element.

– Matthew Boxwell