its for my science class
2007-09-03 09:23:04 · 11 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Mercury is more sensitive to the changes in air pressure so the barometer doesn't need to be as big.
2007-09-03 09:26:48 · answer #1 · answered by Mandy 6 · 1⤊ 4⤋
All the answers above are very good and i want add to them that water sticks to the wall of the barometer as it comes down while mercury does not - and the mercury has a a clear curve on top of it that gives a definitive reading of the barometer due to it's nature and color.
2007-09-03 09:44:07 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Torricelli devised an experiment -- conducted by his student Vincenzo Viviani in 1643 -- which actually proved air had weight. To do so, they constructed the prototype mercury barometer. Torricelli had first built a water barometer, but it required a very long (18 m / 60 ft) and clumsy glass tube. By substituting mercury, which at room temperature is a liquid and about thirteen times more dense than water, he was able to reduce the working tube length to around 90 cm (35 inches)....
2007-09-03 15:22:37 · answer #3 · answered by Anonymous · 0⤊ 0⤋
believe the original barometer was made with water and
was about 30 feet tall. The denser mercury accomplishes
the same thing in a much smaller container.
2007-09-03 09:40:18 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Water is much less dense, and has a much higher vapor pressure than mercury. A water barometer would have to be about 40 ft tall.........
Not only that, but the vapor pressure of water tends to vary greatly with temperature, making a water barometer less accurate.
2007-09-03 09:31:56 · answer #5 · answered by WOMBAT, Manliness Expert 7 · 2⤊ 1⤋
The weight of the liquid in the barometer tube balances Atmospheric pressure and varies with it allowing it to be measured.
Hovever atmospheric pressure is large (100,000Pa)
Thus if water was used (as Evangelista Torricalli did in the very first barometer) it would require a very long tube to provide enough balancing weight. (about 10meters)
So we use a far much denser liquid- mercury and our barometric tubes can be less than one meter long.
2007-09-03 09:34:28 · answer #6 · answered by adrian r 2 · 1⤊ 1⤋
Work out how tall the tube would have to be for a water barometer.
And for a mercury barometer.
Now think about it.
2007-09-03 09:33:56 · answer #7 · answered by monsewer icks 4 · 2⤊ 1⤋
Mercury is used because it's cohesive forces (attraction to itself) is much greater than is adhesive forces (the glass medium of the tube). This means it presents a range long enough to be relatively accurate in reading without being so long as to accommodate the "climbing" or "capillary" rise of water.
2007-09-03 09:34:32 · answer #8 · answered by Aaron H 2 · 0⤊ 2⤋
Because mercury has a greater density and low viscosity.
2007-09-03 09:37:04 · answer #9 · answered by mimi 3 · 0⤊ 0⤋
the mercury is slightly more than 12x heavier than water, so each inch of Hg would be equal to more than a foot of water.
2007-09-03 09:35:57 · answer #10 · answered by lare 7 · 2⤊ 1⤋