Why is there vacuum above the level of mercury in a mercury barometer?
The top of the barometer is filled with nothing (vacuum) because the mercury must have the space to expand and contract without any other force affecting it; a gas or liquid in the top would have its own pressure against the mercury and give inaccurate readings.
How will the height of the mercury column change when the atmospheric pressure decreases?
Atmospheric Pressure and Altitude At sea level, a mercury column will rise a distance of 760 mm. At higher altitudes, the atmospheric pressure is decreased and so the column of mercury will not rise as high. On the summit of Mt. Everest (elevation of 8848 m), the air pressure is 253 mmHg.
How does inches of mercury work?
A column of air an inch square extending out to the top of the atmosphere (over 20 miles) weighs about 14.5 pounds, and therefore exerts a pressure of 14.5 pounds per square inch (1 bar) at sea level. So “an inch of mercury” is the pressure equivalent of about 1/30th of an atmosphere.
Why the density of gas is not constant?
For a static gas, the molecules are in a completely random motion. Because there are so many molecules, and the motion of each molecule is random, the value of the density is the same throughout the container. Density is a scalar quantity; it has a magnitude but no direction associated with it.
What gas has the lowest density?
Hydrogen. Hydrogen, being the lightest existing gas (7% the density of air), seems to be the most appropriate gas for lifting. It can be easily produced in large quantities, for example with the water-gas shift reaction, but hydrogen has several disadvantages: Hydrogen is extremely flammable.
What are the two densest gases?
Answer: The densest gas element is either radon (monatomic), xenon (which forms Xe2 rarely), or possibly Oganesson (element 118). Oganesson may, however, be a liquid at room temperature and pressure. Under ordinary conditions, the least dense element is hydrogen, while the densest element is either osmium or iridium.
Why is gas less dense than liquid?
This is because the particles are tightly packed in both states. The same number of particles in a gas spread further apart than in the liquid or solid states. The same mass takes up a bigger volume . This means the gas is less dense.