Samples of Elements

First day of Gen Chem: Metals and non-metals; solids, liquid and gas elements; compound of elements.

Copper, sulfur, lead, iron, antimony, iodine, carbon as powder and graphite sample, mercury, copper iodate, oxygen balloon.

Wooden Dowel Wave Machine

Large (20 feet long) Shive wave machine that can clearly show the reflection and transmission of a pulse at the boundary of fast and slow media.

What it shows:

Being so large (20 feet long), transverse traveling waves on this apparatus are easily seen by a large audience. The propagation speed of the waves is much slower than on the Shive Wave Machine, giving the audience time to process what's going on. The apparatus can be used to show three properties of waves: (1) wave speed is inversely proportional to the square root of the medium's inertia, (2) waves traveling from a...

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Hydrogen Peroxide Decomposition by Iodide

Hydrogen peroxide 30% in a large round flask decomposes to boiling water and oxygen when postassium iodide is added.

The 12L Round Bottom Flask is set on white C-Fold towels covering a large cork ring on the lab bench.  100-150 ml of 30% hydrogen peroxide is carefully poured in. The liquid should be visible against the white towels from the perspective of the class, and any camera, if used.

The catalyst is 5 g of potassium iodide in a small plastic weighing boat labeled KI.

Safety goggles and gloves. Raise the projection screen and make sure the flask is...

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High Road, Low Road

Which road is faster? A kinematics concept Puzzler.

high low road

What it shows:

Horizontal and vertical motions are independent of each other.

How it works:

Two balls, starting with the same initial horizontal velocity, take two different paths: the...

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Resonant Fountain Tube

Standing sound waves in a glass pipe are made evident by the fountains of kerosene inside the pipe.

What it shows:

The air inside a very large glass pipe (partially filled with a fluid) is acoustically excited into a standing wave. Once resonating, the locations of the velocity antinodes inside the pipe are dramatically made evident by the vigorous agitation of the fluid, resulting in fabulous foaming frothing fountains of fluid. The velocity of sound can also be determined by noting the resonance frequency and measuring the distance between antinodes....

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TV Color Perception

What it shows:

The full spectrum of colors (including white) in a television picture is produced by the additive mixing of only three colors: red, green, and blue.

How it works:

In a color television tube, three separate electron beams are focused so as to strike the appropriate phosphor dot on the screen. By looking at the television screen under considerable magnification, one can clearly see that there are only three phosphors which are stimulated by the electron beam(s). The apparatus is diagrammed below.


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Reactions of Li, Na, and K with Water

Lithium, sodium, and potassium undergo reactions with water.

Two liters of warm water in large pyrex vessel, covered with fine mesh stainless steel screen, is on a stool close by in-floor vent hood.  Add a few drops from the phenolphthalein indicator bottle, and a few drops of 1M hydrochloric acid if the warm tap water turns pinkish.

Video camera is clamped to the stool leg, and pointed at the bottom of the beaker. Before class, frame the shot and focus on the center of the beaker.

Using the long forceps, pick out the coil of lithium wire from the mineral oil in...

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Shoot the Monkey

Monkey released from platform is shot by simultaneously fired cannon.

What it shows:

This is a demonstration of the independence of the horizontal and vertical components of velocity of a projectile. Often referred to as "the monkey and hunter," the problem is the following. A hunter (at ground level) aims a gun at a monkey hanging from a branch high in a tree. The monkey, being very intelligent, does not want to be shot. It knows that light travels faster than bullets and reasons that, if it lets go of the branch the instant it sees the flash of the gun,...

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