Barometer

Definition

A barometer is an instrument used to measure atmospheric pressure. It helps determine weather changes and is crucial in studying gas behavior.

5 Must Know Facts For Your Next Test

1. Barometers can be of two types: mercury barometers and aneroid barometers.
2. The standard atmospheric pressure at sea level is 760 mmHg or 1 atm.
3. Barometric pressure readings are essential for calculations involving the Ideal Gas Law, $PV = nRT$.
4. Changes in barometric pressure can indicate weather changes; a falling barometer suggests stormy weather, while a rising one indicates fair conditions.
5. Torricelli invented the mercury barometer in 1643, which led to the discovery that air has weight.

Review Questions

• What are the two main types of barometers?
• How does a falling barometer reading affect weather predictions?
• What is the standard atmospheric pressure at sea level in mmHg?

Related terms

Atmospheric Pressure:

The force exerted by the weight of the atmosphere above a surface area.

Ideal Gas Law:

$PV = nRT$, where P is pressure, V is volume, n is moles of gas, R is the gas constant, and T is temperature.

Mercury Barometer: A type of barometer that uses mercury to measure atmospheric pressure.