Question

What are two reasons why mercury, rather than water, is used in barometers?

a) Mercury is denser and less viscous than water.
b) Mercury has a lower boiling point.
c) Water is opaque.
d) Mercury is less toxic than water.

Answer 1

Mercury is used in barometers due to its density and lower boiling point compared to water.

Step-by-step explanation:

Mercury, rather than water, is commonly used in barometers for two main reasons:

1. Mercury is denser and less viscous than water. Its density allows for a shorter column of liquid, making barometers more compact and convenient to use.
2. Mercury has a lower boiling point than water. This means that mercury remains in liquid form even at higher temperatures, allowing barometers to function accurately in various environments.

The reasons why mercury is used in barometers instead of water are primarily due to mercury's high density and low viscosity. Firstly, mercury is approximately 13.6 times denser than water, which means that for a barometer to measure standard atmospheric pressure, a column of mercury only needs to be about 760 mm (29.92 in.) tall, whereas a water barometer would need to be over 10 meters high.

This makes mercury barometers much more practical and easier to use and read. Secondly, because mercury is less viscous than water, it responds more quickly to changes in air pressure, making it more effective for accurate measurements.