Grace Wynveen
Pressure and Volume Lab
In this lab we changed the volume of a set number of air particles by moving the piston on a syringe. The temperature stayed constant throughout the experiment, meaning the particle speed didn’t change. We found that as the volume increased, the pressure recorded by the pressure sensor decreased. This illustrates Boyle’s Law. The decrease in pressure occurs because as volume increases particles move further apart, causing a decrease in the number of collisions. This exerts less force on the inside of the container. As we decreased the volume, the pressure increased.
The picture above demonstrates the inverse relationship between pressure and volume. #1 and #2 each have 12 particles and 2 whooshies, showing that the number of particles and temperature stayed the same. To show an increase in volume, I drew the container bigger. To show an increase in pressure I drew less collision events because the number of collisions decreases when pressure decreases.
Pressure and Number of Particles Lab
In this lab we put different numbers of particles in a syringe and kept the volume and temperature constant. We did this by starting the syringe at different volumes and then moving the piston to allow each sample 10.0 mL of space. The greater the number of particles we fit into the 10.0 mL, the greater the pressure in the syringe. The increase in pressure is caused by a greater number of collisions that occur because the particles are packed more densely.
The picture above demonstrates the direct relationship between pressure and number of particles. The volume and temperature remains the same, so I drew the container the same size and included the same number of whooshies in #1 and #2. #1 has 8 particles and 3 collision events, whereas #2 has 16 particles and 6 collision events to illustrate both the number of particles and the pressure increasing.
Pressure and Temperature Lab
In this lab the volume and number of molecules of our gas sample stayed constant. We placed our gas sample in water at 4 different temperatures. As the temperature increased, the pressure of the gas sample increased. This increase occured because the gas particles collided with the glass container it was in. When the particles of water collided with the same glass, energy was transferred from the gas to the water. The gas had lost energy, which caused the particle speed to decrease. Because the particle speed decreased, the number of collisions with the wall of the container decreased. This shows a direct relationship between pressure and temperature, which is defined by Guy-Lussac’s Law.
The picture above demonstrates the direct relationship between pressure and temperature. I drew the containers for #1 and #2 the same size to indicate a constant volume and I included 11 particles in each container to show that the number of particles does not change. The increase in temperature is illustrated by another whooshie on each particle in #2. To show the pressure increasing, the number of collision events increases from 2 in #1 to to 4 in #2.
Thermometer Discussion
When a thermometer is placed in a warmer environment, the liquid inside it expands and rises. We know this because as the air in the outside environment, which is a gas and is in a constant state of motion, collides with the glass tube of the thermometer it transfers energy to the liquid as it also collides with the glass. This increase in energy causes an increase in particle speed, which in turn causes the particles to move further apart, increasing the volume so that the liquid rises in the thermometer. Thermometers are not affected by pressure because the air is removed from them, making them vacuums.
*The before picture is right after moving the thermometer into the warmer environment.
The picture above demonstrates what happens at a molecular level when a thermometer is placed in a warmer environment. In the before and after picture the volume of the thermometer remains constant because I drew the containers the same size. There are 2 whooshies on the air particles in each drawing to show a constant temperature in the air outside. The air particles are colliding with the thermometer to show a transfer of energy. The temperature inside the thermometer increases. That’s illustrated by the increase in whooshies from the first to the second picture. The increase in temperature causes the liquid to expand, which is shown by drawing the particles farther apart and rising up the thermometer. There are no air particles inside the thermometer because thermometers contain no air.
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