Lab 14: Titration Lab by Katie, Maya, Alison and Meghana

In this lab we used a very stressful, difficult, and painstaking process called titration. We combined acid (vinegar) and a base (NaOH). An indicator, phenolphthalein, was used to tell when the solution went from its acidic form to basic form. At this point we would know the volume of the base and could use MV=MV to solve for the molarity of the acid. Then we used the pH of the base to find molarity of the base, and used this to find percent ionization. The ionization of vinegar was .456%. It is low because vinegar is a weak acid and so very few of its molecules ionize and become ions. 

We used a barrette to carefully combine the base and acid. The acid was distilled in water and we kept adding more base until the indicator showed that the solution had made the transformation. 

Lab 13: A Guided Inquiry Lab by Katie and Maya

Introduction:
In this lab we had to find the identity of an unknown salt. Salt have individual solubilities, so by dissolving them at different temperatures, we could tell what compound they were. We used water as the solvent, and dissolved the salt as the solute. We referred to the solubility curves to identify the solid.

Procedure:
First, we referred to the solubility curve of NaNO3, KNO3, and NaCl. We decided that if we dissolved 7 grams in 10 grams of 80 degree celsius water, then it cannot be NaCl because the graph shows that at 80 degrees 7 grams of NaCl would dissolve. After eliminating NaCl we had to test a point on the graph between KNO3 and NaNO3 so we added 7 grams to 10 grams of water at 30 degrees to test if it would dissolve. If it dissolves it then it is NaNO3 but if it cannot dissolve all 7 grams then it is KNO3.

Quantitative Data:
Trial 1- 10 grams of water
             7 grams of salt
             heated to 80 degrees celsius

Trial 2 - 10 grams of water
              7 grams of salt
              heated to 30 degrees celsius

Qualitative Data:
Trial 1- All of the salt dissolved so it is not NaCl

Trial 2- The salt did not dissolve therefore it is KNO3

Conclusion:
Because the 7 grams of salt did not dissolve in 10 grams of water at 30 degrees we knew that it could not be NaNO3 because it would have dissolved according to the solubility curve. Also, it is KNO3 because it 7 grams of salt dissolved in 10 grams of water at 80 degrees, which it would not have if it were NaCl according to the solubility curve. Therefore we narrowed it down to KNO3. For most solids, increasing the temperature increases the solubility. Keeping the temperature of the solution at constant was very challenging but we managed to keep it level during our experiment.

Heating the solutions in a hot bath!

Lab 12: Alka Seltzer and the Ideal Gas Law by Katie and Maya

We found the amount of CO2 produced by combining citric acid and baking soda. We did this by measuring the volume the gas took up, finding the pressure and using PV=nRT to find the amount of moles.

Data:
Mass of alka seltzer- 10.07 grams
Circumference of balloon- 38 cm
Volume of water that fits in balloon- 1066 mL
Room Temp. - 20 degrees celsius
Barometric pressure- 759.2 mmHg

1. Discuss an area in this lab where experimental error may have occurred.

The water residue that was left inside the balloon when we rinsed it may have mad our measurements inaccurate. Also we had difficulty transferring all of the alma shelter powder into the balloon so we may not have had all of the residue in the reaction.

2. Choose one error from above and discuss if it would make 'n' the number of moles of CO2 too big or too small.

Spilling the powder and not having all of it in the reaction may have caused our calculations to yield a lower the number of moles than what it actually was. 

3.  Calculate the volume of the balloon mathematically using the circumference you calculated in cm.

The actual volume of the volume of the gas that filled the balloon is 926.62

4. Compare you answers to #3 to the volume obtained by filling the balloon with water. Is it close? Which do you feel is more accurate and why?

They were off but still relatively close. The calculation is more accurate because experimental measurements may have been inaccurate. 

5. List two differences between a real gas and an ideal gas.

Real gases have volume while ideal gases don't. Also, we assume that ideal gases have no intermolecular forces but in reality real gases do.

6. Would the CO2 you collected in this lab be considered ideal? 

No, because the gas that we found has volume, and although they are weak, they have intermolecular forces.

Advanced Questions:

1. The mass of the CO2 in grams was 2.062 g with the citric acid as the limiting reagent.

2. Our percent yield was 92.14%

3. Because some of the CO2 dissolved, the n-value we found may be a little less than the actual amount of moles. 

  

Lab 11B: Calories in Food by Katie and Zoe

We were able to find the number of food calories by solving for "chemistry calories". By burning the food and letting the heat be absorbed by water, we could solver the equation q=mcΔt where q lost by food is equal to q gained by water. Here is our data below:

Questions:

1. We measured the temperature of the water.

2. We measured both the energy released by the food and gained by the water because they are equal and set the two equations equal.

3. The energy is absorbed by the can or the beaker. It is absorbed into its surroundings.

4. I was surprised that the individual foods had such small amounts of calories, and that the cheese puff has less calories than the pecan and cashew. 

Lab 10: Evaporation and Intermolecular Attractions by Katie and Maya

2. Explain the differences in the difference in temperature of these substances as they evaporated. Explain your results in terms of intermolecular forces.

A larger differences in temperature means that more of the substance was able to evaporate. This means that the intermolecular forces are weak and readily break.

3. Explain the difference in evaporation of methanol, ethanol, and n-butanol. Explain your results in terms of intermolecular forces.

Methanol has the highest change in temperature, ethanol has the second highest, and n-butanol had the lowest. This means methane had the most evaporation with the weakest intermolecular forces, while ethanol had the less evaporations, and n-butanol had the least evaporation with the strongest intermolecular forces.   

4. Explain how the number of OH groups in the substances tested affects the ability of the tested compounds to evaporate. Explain your results in terms of intermolecular forces. 

The more OH in a compound, the more hydrogen bonds. This means that it is harder to break the bonds and have the substance evaporate which is why Glycerins temperature went up. 

Lab 7: Flame Test Lab by Katie, Roz and Maya

In this lab, we burned different compounds. The colors that they gave off were a result of excited electrons from the heat of the bunsen burner. Each element gives off a different color when burned so we could identify the the elements that the wooden sticks were soaked in.

PRE-LAB:

1. When electrons absorb energy in an atom, it will move to a higher energy level. This is the excited start. The grounded state is when the electrons are all at their lowest energy level.

2. Tp emit is to let off or discharge.

3. The excess energy that the atoms use comes from heat from the bunsen burner.

4. Different colors travel at different wavelengths. Each element emits different photons of different wavelengths. This is the emission spectrum.

5. We wash would wash the nichrome wires between each flame test so we don't burn a combination of elements.

Calcium

Copper 

Potassium

Unknown #1: Strontium Nitrate

Unknown #2: Potassium Chloride

We were able to identify these unknown substances by comparing the color to the colors of the known chemicals. When the colors of #1 burned red we knew it was Strontium Nitrate. When #2 burned purple we knew it was Potassium Chloride.

Electron Configuration: You're Never Too Old for Battleship

Don't be fooled by the board game. Electron configuration was a difficult concept to learn, but by the end of this game, we were pros. The most challenging part was when the lanthanides or actinides came into play and we had to count in the f orbitals. However this game helped me learn how to apply the noble gas shorthand when writing the configurations, and how to locate and element based on its electron configuration.

Happy one month anniversary to my camp mate and board game buddy even though all your
battleships were in the d-block