Question

1. why is the fluid in a barometer mercury, rather than water or another liquid?

1. explain how a straw works and why suction is not involved.

1. one standard atmosphere of pressure (sp) is equivalent to ______mmhg.

1. convert pressure measurements from one system of units to another in the following problems.

1 atmosphere = 760 mmhg = 14.7 psi (pounds per square inch)

a. 320 mmhg x __________ = atm

b. 30.0 psi x _____________ = mmhg

c. the barometric pressure in breckenridge, colorado (elevation 9600 feet) is 580 mm hg. how many atmospheres is this?

Explanation:

Question 5

Mercury is used in barometers because it has a very high density (about 13.6 times that of water) and low vapor pressure. A high density means the column height needed to balance atmospheric pressure is manageable (around 760 mm for 1 atm), while water would require a column over 10 meters. Low vapor pressure ensures minimal vapor in the vacuum space, making the measurement accurate. Also, mercury doesn't wet the glass, so the meniscus is clear for reading.

When you suck on a straw, you remove air from the straw, lowering the pressure inside it (below atmospheric pressure). The atmospheric pressure acting on the surface of the liquid (in the cup, for example) then pushes the liquid up the straw into your mouth. Suction is not involved because there's no "pulling" force; it's the external atmospheric pressure pushing the liquid. The pressure difference between the outside (atmospheric) and inside the straw (lower pressure) causes the liquid to rise.

By definition, one standard atmosphere (1 atm) of pressure is equivalent to the pressure exerted by a column of mercury that is 760 millimeters high at 0 °C and standard gravity. This is a well - established conversion in pressure measurement.

Answer:

Mercury is used due to its high density (reducing column height), low vapor pressure (accurate vacuum), and non - wetting of glass.

Question 6