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Mercury has a very low vapor pressure. Vapor pressure is the pressure exerted by the gaseous form of a liquid on the liquid itself when both states are in equilibrium. A higher vapor pressure means (which is known as a volatile substance ← [this statement is unclear and seemingly unrelated. I cannot determine its relevance, but perhaps it can help you]) more pressure is exerted by the ambient atmosphere on the liquid and hence it cannot rise easily to denote the pressure increase. Hence liquids with low vapor pressure are usually preferred as they can rise easily or they can show more sensitivity. Water has a relatively high vapor pressure, and thus is not as sensitive to changes in pressure as mercury is.
This is why when we measure pressure with water, we divide the water level change by 13.6, which is the ratio of the density of HOH to the density of Hg. Our answer changes from the non-standard pressure measurement in milimetres of HOH to the commonly-used milimetres of Hg
Following are the reasons why mercury and not water is used in a barometer:
1. Mercury is relatively denser than water, consequently the length of the column of water would have to be about 34 feethigh to exert pressure equal to that of the atmosphere while the column of mercury need to be only 30 inches to exert pressure equal to that of the atmosphere.
2. Mercury has a very low vapor pressure when compared to that of water. So it is more sensitive than water to the changes in the atmospheric pressure and rises more quickly to record the changes in the atmospheric pressure.
3. Mercury's freezing point is much lower than that of water's so it can record the atmospheric pressure at temperatures below that of 0 degrees centigrade.
4. Mercury does not evaporate easily so very little mercury vapor enters the vacuum above the mercury in the tube.
5. Mercury being a metal shines brightly and so can be used to read the markings on the tube easily.
What else can I help you with?
What is a barometer filled with?
A barometer is typically filled with either mercury or a special type of alcohol, such as ethanol or isopropanol. Mercury has traditionally been a common choice due to its density and stability for measuring atmospheric pressure.
What measures a barometer with Mercury?
A barometer that uses mercury measures air pressure by monitoring the height of the mercury column in a tube. As air pressure changes, the mercury level rises or lowers in response. This instrument is called a mercury barometer.
What is the most commonly used barometer?
The most commonly used barometer is the mercury barometer.However, it is not easy to transport but it gives more accurate results. Another type of barometer is Aneroid barometer which is easy to transport and handle.
A decrease in the height of a column in a mercury barometer means that .'s surface?
When air pressure increases, the mercury in a barometer rises.
When air pressuer increases what does the mercury in the barometer do?
Air is "pushed" into the open end of a barometer when the pressure is higher, meaning the mercury closer to the closed end of the barometer - where the pressure is measured - will rise.
Which liquid is used in an aneroid barometer a mercury b alcohol c none?
mercury
What is a barometer with Mercury called?
A mercury barometer.
What is a barometer filled with?
A barometer is typically filled with either mercury or a special type of alcohol, such as ethanol or isopropanol. Mercury has traditionally been a common choice due to its density and stability for measuring atmospheric pressure.
Why is mercury preferred to alcohol as a thermometric fluid?
what are the qualities of mercury over alchoholic as thermometric liquid
What is in a thermometer and a barometer?
A thermometer measures temperature - most are now electric but they used to have alcohol or mercury in them. A barometer measures air pressure - they are now electric but used to have air in them (in a bellows with a spring).
What does a barometer has in it?
barometer has mercury inside it .
What type of barometer was invented first the aneroid or the mercury?
The first barometer that was invented was the MERCURY barometer. a mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury. (:
What are the uses of a Mercury barometer?
A Mercury barometer is used to measure atmospheric pressure.
Why use of alcohol is preferred over mercury in thermometers?
Alcohol is less expensive and the compounds formed from oxides of Mercury are poisonous while alcohol is less problematic.
What measures a barometer with Mercury?
A barometer that uses mercury measures air pressure by monitoring the height of the mercury column in a tube. As air pressure changes, the mercury level rises or lowers in response. This instrument is called a mercury barometer.
Which statement accurately describes a difference between a mercury barometer and an aneroid barometer?
One statement to accurately describe a difference between a mercury barometer and an aneroid barometer is that a mercury barometer is a closed tube containing mercury. An aneroid barometer is a closed, flexible container of gas.
How can an aneroid barometer give reading in inches of mercury when it doesn't use any mercury?
Good question.Look at it like this if you had two barometers side by side, one a mercury barometer and the other a barometer that reacted to changes in air pressure using some bellows and a spring.Then, as the pressure changed you marked the second barometer positions and noted on the dial the inches reading from the mercury barometer, the second barometer measurement scale would mimic the real mercury barometer even though it did not actually use any mercury.
