Why is water not used as a barometric liquid? (2024)

FAQs

Why is water not used as a barometric liquid? ›

Water is highly inconvenient to take a tube of height 10.4 m for a barometer. The vapor pressure of water is high so its vapors in the vacuum space will make the reading inaccurate.

In conclusion, although using water as a substitute for mercury in barometers would be environmentally friendly and cost-effective, its disadvantages of height, vapor pressure, and sensitivity to temperature changes make it less practical than mercury in constructing a barometer.

Water barometer will nearly support 10.34 m of water at sea level and logically speaking, it is impractical to have such a long tube, and hence water barometers are not used. Water is not easily visible in a glass tube because water is transparent.

A barometer quantifies pressure by balancing the pressure force with the weight of the liquid column. We can use any liquid to construct a barometer but we use mercury because of its high density. A denser/heavier liquid means shorter height of the column to balance the pressure.

You can make a basic aneroid (air) barometer with a balloon, a jar, and a few other simple supplies. Alternatively, you can make a water barometer with a bottle, some plastic tubing, and a ruler.

Mercury is the liquid used in a barometer. Some of the properties that make it a suitable choice are listed below: High density: Smaller length of mercury (76 cm) can balance the atmospheric pressure. It is more sensitive to changes in pressure.

An aneroid barometer is made without the use of mercury or any other fluid. It consists of a small, flexible metal chamber called an aneroid capsule, made of a beryllium/copper alloy.

The abundance of mercury over water in nature. A smooth flow of mercury in the tube as it does not stick to the glass. A shorter tube length because of the high density of mercury.

However, using a standard water column manometer carries some disadvantages: first, pressure reading can be time-consuming; second, these manometers are bulky in size, therefore require manual dexterity for stability and sometimes one may require two people during measurement; third measurements may easily be altered ...

Why water and not mercury is used as a manometer fluid? ›

Why do we use mercury in the manometer while measuring the pressure of fluids? The main reason is because it's quite dense (13600 kg/m^3; cf water at 1000 kg/m^3), so atmospheric pressure can be balanced by a column of mercury only 760 mm (30") high, whereas you'd need 10.3 m (34') of water.

Typical manometer liquids are mercury, water, and light oils. It's worth saying here that mercury was a common manometer fluid in the past, but has largely been replaced due to its environmental and health hazards. Quite often the liquid is colored to help detect the fluid movement.

So if we want to used water instead of mercury height of the barometer will be 13.6 times greater than for mercury. = 1020 cm for pressure equivalent to 75 cm of the mercury barometer.

The water should be about 1” up the spout of the Storm Glass. If the water is not at this level, fill the syringe with air and insert the filling tube back into the top of the water chamber.

Our simple barometers consist of an empty bottle turned upside down in a cup. The wider sides of the bottle rest on the rim of the cup, so that the mouth of the bottle is not touching either the bottom or sides of the cup. Water that we put in the cup will rise to a certain level up the neck of the bottle.

Mercury has many advantages when used as a measuring liquid in a barometer tube. Mercury has high density. Because of this property, when there is a change in pressure the change in height of the mercury in the barometer tube will be very reasonable.

An aneroid barometer is an instrument for measuring pressure as a method that does not involve liquid. Invented in 1844 by French scientist Lucien Vidi, the aneroid barometer uses a small, flexible metal box called an aneroid cell (capsule), which is made from an alloy of beryllium and copper.