Crushing Can:
youtube video:
/watch?v=SBpqT-u8sjo
1. Explain why the can collapsed using the Combined Gas Law where T1 is the initial temperature of the air inside the can before the can was inverted and T2 is the temperature of the air inside the can after it was plunged into the ice water.
2. Why did the can need to be inverted?
3. Adding water to the can and boiling it pushes the air molecules out of the can. Why is this step needed?
1. To explain why the can collapsed using the Combined Gas Law, we need to understand the relationship between pressure, volume, and temperature of a gas. According to the Combined Gas Law, if the temperature of a gas decreases while the volume and number of gas molecules remain constant, the pressure of the gas will also decrease.
In the case of the crushing can experiment, when the can was initially filled with air and sealed, the temperature of the air inside the can was at room temperature (let's call it T1). Then, when the can was inverted and submerged in ice water, the air inside the can came into contact with the colder temperature of the water, causing the temperature of the air inside the can to decrease (let's call it T2). This decrease in temperature caused the pressure inside the can to decrease as well. However, since the volume and number of gas molecules remain constant, the decrease in pressure creates an imbalance with the external atmospheric pressure, resulting in the can collapsing.
So, in summary, the crushing of the can is a result of the decrease in temperature (using the Combined Gas Law) causing a decrease in the pressure inside the can, leading to an imbalance with the external pressure and causing the can to collapse.
2. The can needed to be inverted because the experiment aims to demonstrate the effect of temperature change on pressure. Inverting the can ensures that the cold water comes into direct contact with the air inside the can, facilitating a greater and faster decrease in temperature. This allows for a more dramatic demonstration of the crushing effect when the temperature decreases rapidly.
3. Adding water to the can and boiling it serves two purposes. First, water acts as a heat conductor, allowing for a more rapid transfer of heat to the air inside the can. By adding water and heating it, the temperature of the air inside the can increases considerably. Second, the boiling water produces steam, which displaces the air inside the can. This step is needed to remove the majority of the air molecules from the can, leaving mostly steam.
Removing the air from the can is important because it allows for a greater temperature change with a smaller amount of gas inside, making the crushing effect more pronounced. The steam inside the can condenses when the can is plunged into the ice water, creating a partial vacuum and further contributing to the collapse of the can when the pressure inside becomes lower than the external atmospheric pressure.
So, adding water and boiling it in the can helps increase the temperature and also removes air, both of which enhance the crushing effect during the experiment.
1. The can collapses because of the application of the Combined Gas Law, which states that the pressure of a gas is directly proportional to its temperature, assuming constant volume and amount of gas. When the can is initially filled with air at a certain temperature, the gas molecules inside have a higher average kinetic energy, resulting in a higher pressure. However, when the can is inverted and submerged into ice water, the temperature of the air inside decreases (T2). According to the Combined Gas Law, if the temperature decreases while the other variables remain constant, the pressure will also decrease. As a result, the pressure inside the can becomes lower than the atmospheric pressure, causing the external air pressure to crush the can.
2. The can needs to be inverted because when it is turned upside down, the opening of the can is submerged into the water. This allows for better heat transfer between the can and the water. By doing so, the temperature of the air inside the can can decrease more rapidly, enhancing the pressure difference between the inside of the can and the outside. This promotes a more dramatic collapsing effect when the can is crushed.
3. Adding water to the can and boiling it is important to expel the air molecules from the can. When water is heated, it undergoes a phase change from liquid to gas, forming water vapor. This vapor displaces the air that was initially present in the can, effectively pushing it out. By removing the air from the can, we ensure that only the vapor occupies the can's volume, allowing for a more efficient demonstration of the collapsing effect once the can is cooled down by immersion in ice water.