DC-072, Determination
of Absolute Zero -A gas pressure gauge connected to a metal container
tells the pressure of the gas inside. By heating the gas above (and cooling
it below) room temperature, the quantitative relationship between pressure
and temperature is determined.
DC-073, Pressure versus Volume in a Gas -A closed apparatus, which traps air in a calibrated glass vessel over mercury, is used to measure the pressure and volume of a gas sample. The system is designed so that the pressure applied can be adjusted by raising or lowering a bulb filled with mercury. The volume occupied by the gas and the levels of both the internal and external mercury surfaces can be measured. From these data together with the barometric pressure a quantitative relationship between pressure and volume is obtained.
DC-080, Graham's Law of Diffusion -Hydrogen chloride and ammonia diffuse from opposite ends of a long tube. They meet and react to produce ammonium chloride, a white solid powder. The distances of the white powder from either end of the tube are measured, and the ratio compared with a predicted ratio from Graham's Law. The experiment is not expected to give close quantitative agreement between calculated and observed values, but the ammonia does diffuse faster than the HCl, as expected.
DC-081, Air Bubble in Carbon Dioxide -A soap bubble falls to the bottom of an open tank filled with air. When the same tank is filled with gaseous carbon dioxide, a similar bubble floats.
DC-082, Weighing Carbon Dioxide Gas -A balance is constructed with a 'beam' from a meter stick and "pans" from large, low-weight brown paper grocery bags. The pivot point is a hole in the center of the meter stick balanced on a nail or other suitable cylindrical object. When carbon dioxide gas is "poured" into one of the bags, it displaces air. That pan becomes heavier and moves downward.
DC-084, Methane Bubble; Rising Cinder -A soap bubble filled with methane gas rises in air. The bubble may be ignited; it burns quietly with a luminous flame. A piece of paper from the inside of a ditto master is ignited. When nearly completely burned, the hot cinder rises in air. (This experiment is sometimes called the paper rocket.)
DC-086, Dihydrogen Diffusion -An apparatus is constructed so that dihydrogen is able to diffuse into a flask and thereby increase the gas pressure forcing liquid to be expelled from the flask through an exit tube. When the source of dihydrogen is removed, the dihydrogen escapes more rapidly than air can replace it and air is drawn in through the same tube.
DC-087, Dry Ice in a Balloon -Solid dry ice is placed in a balloon. It sublimes, and the resulting gas occupies a much larger volume than the solid; the balloon expands greatly, and often bursts. When a balloon is filled with a gas more dense than air, the balloon may serve as a lens focussing sound and giving the effect of amplifying the sound. Speaking through the balloon to the class demonstrates this effect.
DC-088, The Collapsing Can -When heated enough to boil water, a soda can becomes filled with water vapor at atmospheric pressure. When cooled suddenly, the vapor pressure drops substantially below atmospheric pressure. Either the can will collapse, or water will be pushed into the can. Aluminum soda cans usually collapse in a spectacular fashion.
DC-090, Boiling Water Under Reduced Pressure -A closed system consisting of a filter flask is connected to a manometer tube. When 20 mL of air is injected into the flask, a dramatic change occurs in the manometer levels. When 0.1 mL of a volatile liquid is injected, a similar change occurs.
DC-097, Reaction in a Bag -Equal volumes of anhydrous calcium chloride and sodium bicarbonate are placed in a sealable plastic bag. Aqueous phenol red is added, the bag is sealed, and the ensuing reaction is observed.
