Cork floats

Unlike mass and volume, density does not vary with the amount of a substance. Notice in Figure 1-20 that all the corks float, regardless of their sizes. Notice also that all the pieces of lead sink, regardless of their sizes. Dividing a sample into portions changes the mass and volume of each portion but leaves the density unchanged. A property that depends on amount is called extensive. Mass and volume are two examples of extensive properties. A property that is independent of amount is called intensive. Density and temperature are intensive properties. 

A solid that is not as dense as a liquid will float on it. A denser solid will sink in it. The buoyancy of an object describes how well it floats on top of a liquid. Cork floats because it is not as dense as water. A boat can float because its shape allows it to contain a lot of... 

Six materials with different densities. The liquid layers are gasoline (top), water (middle), and mercury (bottom). A cork floats on gasoline. A piece of oak wood sinks in gasoline but floats on water. Brass sinks in water but floats on mercury. 

Which of the following are chemical properties, and which are physical properties (a) Metallic sodium is soft enough to be cut with a knife, (b) When sodium metal is cut, the surface is at first shiny after a few seconds of exposure to air, it turns a dull gray, (c) The density of sodium is 0.97 g/mL. (d) Cork floats on water, (e) When sodium comes in contact with water, it melts, evolves a flammable gas, and eventually disappears altogether, (f) Household bleach changes the color of your favorite T-shirt from purple to pink. 

Density is a physical property of matter that compares the mass of a substance to its volume. Every substance has a unique density, which distinguishes it from other substances. Density is used in chemistry in many ways. Density can be used to identify a specific substance. Density is also used to predict if an object will sink or float in a liquid or in the air. If an object is less dense than a liquid, the object floats when placed in the liquid. In Figure 2.11, the lead object sinks in water because the density of lead is greater than the density of water. However, the cork floats in water because the density of cork is less than that of water. 

A mode curve exhibiting this shape could indicate that the motor mountings, or the baseplate under the motor, are loose and that the motor is moving vertically. In fact, in the example from which this figure was taken, this is exactly what was happening. The blower s baseplate floats on a one-inch thick cork pad, which is normally an acceptable practice. However, in this example, an inlet filter/silencer was mounted without support directly to the inlet located on the right end of the machine. The weight of the filter/silencer compressed the cork pad under the blower, which lifted the motor-end of the baseplate off of the cork pad. In this mode, the motor has complete freedom of movement in the vertical plane. In effect, it... 

Thomson based h(s configurations on the work of fin American physicist, Alfred Mayer, who had experimented wilh magnets attached to corks and floated In a circular basin of water. When five magnets were placed in the water, for example, they formed a single ring The ad-... 

Cork has a lower density than water, so corks of all sizes float on water. Lead has a higher density than water, so lead pieces of all sizes sink in water. 

There are practical applications of Features 2 and 3. Balloons inflated with helium rise in the atmosphere because the molar mass of helium is substantially lower than that of air. Consequently, the density of a helium-fdled balloon is less than the density of air, and the balloon rises, just as a cork released underwater rises to the surface. Hot-air balloons exploit Feature 3. When the air beneath a hot-air balloon is heated, its density decreases, becoming smaller than the density of the outside air. With sufficient heating, the balloon rises and floats over the landscape. In contrast, cold air is less dense than warm air, so cold air sinks. For this reason, valleys often are colder than the surrounding hillsides during winter. 

Cut a float from cork or wood to a slightly smaller diameter than the test tube or other container to be used. 

Imagine that you place a cork measuring 1.30 cm X 5.50 cm X 3.00 cm in a pan of water and that on top of the cork you place a small cube of lead measuring 1.15 cm on each edge. The density of cork is 0.235 g/cm3, and the density of lead is 11.35 g/cm3. Will the combination of cork plus lead float or sink ... 

When, at the end of about a week, the mass has changed to a pure red color, wash it by decantation (see Note 5 (6), page 10) in a 600-cc. beaker. Most of the excess of sulphur is floated off. Then rinse the red sulphide back into the evaporating dish, leaving behind in the beaker any lumps of black sulphide or globules of mercury. Boil the red sulphide with 50 cc. of saturated sodium sulphite solution to remove the last of the uncombined sulphur wash by decantation with boiling water and collect the mercuric sulphide on a suction filter. Dry the product on the hot plate and preserve it in a 2-ounce cork-stoppered bottle. 

The most convincing evidence of the effectiveness of some lures was obtained at the Berkel, a little border river between Germany and Holland. Here we mainly used the method with artificial entrances, in which funnel-shaped traps were placed (Figure 2). In the slope of the bank 24 holes were dug in which pipes with traps were placed. Three different lures were tested in sixfold against an equal number of controls. In addition, 4 floating traps, baited with apples, and the same lures were tested. Five drops of lure were applied to corks placed on sticks above the funnel traps and similar corks were used on the rafts. 

The cork oak (Q. suber) is another commercially valuable species found throughout the Mediterranean region. The thick bark composed mostly of cork cells can be harvested every 10 years in early summer to provide sheets of soft, smooth cork useful in many ways. The cork cells capture air inside as they dry, making the material extremely resilient and buoyant. Cork has been used to manufacture floats, handles, stoppers, and as insulation, since it is a poor conductor of heat and sound. 

In order to convert the henzalchloride into henzaldehyde, the crude product thus obtained is treated in a round flask provided with an effective reflux condenser, with 500 c.c. of water and 150 grammes of precipitated calcium carbonate (or floated chalk or finely pulverised marble) and the mixture heated four hours in a hemispherical oil-bath to 130° (thermometer in the oil). Without further heating, steam is passed through the hot contents of the flask until no more oil distils over. For this purpose the apparatus necessary (cork with a glass tube) has been prepared before the heating in the oil-bath. 

When all of the ephedrine HCl has been added, an additional 60 ml of chloroform is added. Then the funnel is replaced with another cork, and the stirring is turned up a bit. The stirring is continued for two hours. Then the stirring is turned off, and the flask is allowed to sit for 45 minutes or so. During this period, the unreacted PC15 settles to the bottom of the flask. At the cold temperature inside the flask, some crystals of ephedrine HCl will appear floating on the surface of the brew. 

Density (mass/volume) is a unique property of a materiai. A mixture of wood, water, brass, and mercury is shown, with the cork—the ieast dense—floating on water. Additionally, brass, with a density greater than water but less than liquid mercury, floats on the interface between these two liquids. 

By leaving out the float and closing the inlet, d, with a cork, it can be used for distilling other liquids. 

In Fig. 4 (Figure 251) a small plaster cupel sits on a cork that floats, boatlike, on water in a trough. A small piece of phosphorus in the cupel is ignited and a bell jar inverted over the cupel. The gas remaining in the bell jar is nitrogen. Fig. 5 (Figure 251) depicts a flask containing zinc into which water is first added... 

The best way to keep the temperature of the water constant is to have a large tank of water raised upon a platform, some 5 or 6 feet high, outside the building, which is automatically supplied with water, and into which steam is turned. A thermometer stuck through a piece of cork and floated upon the surface of the tank will give the means of regulating the temperature. 

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