Air Bag Lab

This lab was very cool! Figuring it all out with the calculations was a little tough, but it helped to have some other people help me out in the process. I knew we had to take into account of 5% acetic acid in the vinegar but I didn't know what. I feel so dumb now because you needed to multiply it by 20 to get 100% acetic acid. After passing the pre-lab and all showing Frank our calculations we all picked the biggest bag possible. It was funny because we all had these huge plastic bags. It certainly made calculation easier since we would all have the same volume. The bag turned out to be 3.733 L. That's a lot! At first we were just going to fill the bag 85% full, but we switched it to be 90% full which worked out great! We put about 11.3 g of baking soda and 200ml of vinegar in the bag and shook it all up together with the bag sealed shut. It was scary but cool at the same time to see all the bubbles form and feel the CO2 building up in the bag. I was almost afraid mine was about to explode. But it was all good! I passed the lab! I had successfully made an air bag!

Avogadro's Law

Avogadro's Law:
Tells us that for a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas present.

Equal volumes of gases at the same temperature and pressure have the same number of particles. This relationship hold true for gases at low temperatures.

As the number of moles of a gas to increase, the volume will have to increase in order for the pressure of the system to remain constant.

The volume of 1 mole of gas (at STP) is 22.4 L

Avogadro's Law
Avogadro's Law

Charles' Law

Charles' Law:
Tells us that temperature and volume vary directly with each other. This holds true at constant pressure. As temperature increases = volume increases.

Temperature must be in Kelvin which is 273.15 K. So degree C + 273.15 = _______

As the temperature of a gas increases, it gains energy. This will result in an increase in contacting the sides of their containers -- they are going to want to expand. Keep in mind, Charles Law holds true at constant pressure. If the pressure is going to stay the same, the system has no choice but to allow for the gas to expand --resulting in an increase in the volume of the gas.

If Charles Law is extrapolated backwards, where volume = 0, the value of absolute 0 can be achieved. We call this -273.15 degrees Celsius (Kelvin can't be negative!!!!), absolute zero. There is no kinetic movement of molecules at all.

Charles' Law
Charles's Law

Gas Laws

Characteristics of Gases:
Gases expand to fill their container (no definite volume)
Gases are highly compressible
Gases form homogeneous mixtures
Gas molecules are relatively far apart from one another and exert little influence on each other (collisions are elastic)

You can measure pressure by using a barometer.

The ideal gas is at 1 atm and 0 degrees Celsius or 273.15 degrees Kelvin

Four factors which determine the state of a gas are:
-pressure
-temperature
-volume
-amount in moles

Boyle's Law:
Boyle's law doesn't boil! Temperature is held constant!
It tells us that the relationship between pressure and volume is an inverse relationship.
As we increase the volume of the container, there are fewer collisions with the sides, so we interpret that as a decrease in pressure. As volume increases = pressure decreases.

The Sci Guys: Science at Home - SE2 - EP9: Boyle's Law of Ideal Gases
Boyle's Law

Helpful Links!

Just some helpful links below!

Phase Changes
Phase Changes and Energy
Phase Changes
Chemistry Lecture: Phase Transitions and Phase Diagrams
Chemistry Lecture: Phase Diagrams
Calculations involving heat and specific heat

Basics of Energy

This was a fairly easy unit in all honesty. We learned that thermodynamics is the study of energy transformations. Also we learned that energy is defined as the ability to do work which is a force applied over distance. However work can also be defined as directed energy change resulting from a process. There is kinetic energy, which is the energy of motion, and potential energy, which is stored energy,

We define temperature as a measure of the average kinetic energy of the particles of a substance. We also measure the flow of energy through endothermic and exothermic reactions. Endothermic is when the system gains energy, or takes in energy, from the surroundings. Exothermic is when the system loses energy, or gives away energy, to the surroundings.

We measure energy in Joules (J) and also in calories (c). The conversion is 4.184 Joules in one calorie.

When calculating heat we use the formula Q= mc (change/delta)T
Q is heat in Joules
m is mass in grams
c is specific heat in (J/g degree C)
change/delta T is change in temperature

Boat Races!!!

Man oh man was this a stressful, yet fun, project! My partner and I had to design a boat that would float, not turn into a flaming ball of fire, and be light enough for our putt-putt engine to push it across the gutter using our biodiesel and a candle wick as the fuel. I'm glad my partner was in engineering because I wouldn't know where to start! He came up with a good design to use a milk carton as a boat. We made tons of modifications to the boat the first day of testing but our engine kind of let us down. 2 days later the day of the race we had a different boat that was a little shorter with the engine lower. Our little boat made it across at record time of 55 seconds! Our boat may have been the slowest in our class but in my heart it was the fastest! Slow and steady wins the race! It was cool that we used actual fuel to burn the candle wick to make our boat go. It was a fun project with some stress added to it because getting it across the gutter was a trouble the first day of testing our boat. But we made it!

Here's our cute little boat!