How To Make a Dry Ice Balloon

How To Make a Dry Ice Balloon You usually blow up balloons with air or helium, but did you know you can get a balloon to inflate itself using dry ice? Heres how you perform this simple science project: Dry Ice Balloon Materials BalloonsDry Ice PelletsFunnel (optional) Its easiest to work with a funnel because it holds the neck of the balloon open. If you are working with dry ice pellets, you may find it easier to break or crush them so you can pour them into the balloon. However, if you wear gloves, its pretty simple to do this project with just your hands and a balloon. If you have a carbon dioxide fire extinguisher, you can even make the dry ice yourself. What You Do Hold open the mouth of the balloon.Place or pour dry ice into the balloon.Tie off the balloon so that the gas wont escape.The balloon will inflate as you watch. Youll see water freeze on the outside of the balloon where the dry ice is cooling the air across the surface of the latex. How much the balloon inflates depends on how much dry ice you added. A small amount of dry ice will slightly inflate the balloon, while a large amount ultimately will make it pop. How It Works Dry ice is the solid form of carbon dioxide. At normal atmospheric pressure, dry ice sublimates from a solid directly into a gas. As the gas warms, it expands. Carbon dioxide is more dense than air, so if you drop a dry ice balloon, it will fall to the ground rather than float like a helium balloon. Dry Ice Safety Dry ice is cold enough that it can give you frostbite after a very brief exposure. Its best to wear gloves for this project and to let the balloon inflate on a countertop and not in your hand. Also, dont eat the dry ice. Keep it away from children and pets.

Isochoric Process Definition and Use

Isochoric Process Definition and Use An isochoric process is a thermodynamic process in which the volume remains constant. Since the volume is constant, the system does no work and W 0. (W is the abbreviation for work.) This is perhaps the easiest of the thermodynamic variables to control since it can be obtained by placing the system in a sealed container which neither expands nor contracts. First Law of Thermodynamics To understand the isochoric process, you need to understand the first law of thermodynamics, which states: The change in a systems internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings. Applying the first law of thermodynamics to this situation, you find that: delta-Since delta-U is the change in internal energy and Q is the heat transfer into or out of the system, you see that all of the heat either comes from internal energy or goes into increasing the internal energy. Constant Volume It is possible to do work on a system without changing the volume, as in the case of stirring a liquid. Some sources use isochoric in these cases to mean zero-work regardless of whether there is a change in volume or not. In most straightforward applications, however, this nuance will not need to be considered- if the volume remains constant throughout the process, it is an isochoric process. Example Calculation The website  Nuclear Power, a free, nonprofit online site built and maintained by engineers, gives an example of a calculation involving the isochoric process. Assume an  isochoric heat addition  in an ideal gas. In an  ideal gas, molecules have no volume and do not interact. According to the  ideal gas law,  pressure  varies linearly with  temperature  and quantity, and inversely with  volume. The basic formula would be: pV nRT where: p  is the absolute pressure of the gasn  is the amount of substanceT  is the absolute temperatureV  is the volumeR  Ã‚  is the ideal, or universal, gas constant equal to the product of the Boltzmann constant  and the Avogadro constantK is the scientific abbreviation for  Kelvin In this equation the symbol R is a constant called the  universal  gas constant  that has the same value for all gases- namely, R   8.31  Joule/mole  K. The isochoric process can be expressed with the ideal gas law as: p/T constant Since the process is  isochoric,  dV   0, the  pressure-volume work is equal to zero. According to the  ideal gas model, the internal energy can be calculated by: ∆U m cv  Ã¢Ë†â€ T where the property  cv  (J/mole K)  is referred to as  specific heat  (or  heat capacity) at a constant volume because under certain special conditions (constant volume) it relates the temperature change of a system to the amount of energy added by heat transfer. Since there is no work done by or on the system, the  first law of thermodynamics  dictates  Ã¢Ë†â€ U ∆Q.  Therefore: Q   m cv  Ã¢Ë†â€ T