Name Date Pd Unit 2 Worksheet 2 - Measuring Pressure Problems 1 and 2. Calculate the pressure of the gas in the flask connected to the manometer. 626 773 127  84  43 730  43  773 730 130  26  104 730  104  626 The pressures are equal. 3. What do we mean by atmospheric pressure? What causes this pressure? Atmospheric pressure is the force per unit area exerted on a surface due to the weight of air molecules above it. It is caused by the collisions of the air molecules with that surface. 4. How do we measure atmospheric pressure? Is atmospheric pressure the same everywhere on the surface of the earth? We measure atmospheric pressure using a barometer – the height of a column of mercury indicates the pressure exerted by the air. It is not the same everywhere because temperatures and altitudes are different. Modeling Chemistry 1 U2 ws 2 v3.0 5. Why is the fluid in a barometer mercury, rather than water or another liquid? Atmospheric pressure would support a column of water roughly 10 m high. Because mercury is more than 13 times as dense as water, the column of mercury in a barometer is less than one meter high. 6. Explain why you cannot use a pump like the one at the right to lift water up to the 3rd floor of an apartment complex. This type of pump works by removing air above the column of water in the pipe. As the pressure above the water is reduced, the surrounding air pushes the water up the pipe. The maximum height of a column of water supported by air pressure is about 10 m. 7. One standard atmosphere of pressure (SP) is equivalent to 760 mmHg. 8. 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 b. 30.0 psi x 1atm  0.42atm 760mmHg x 760mmHg 1550 mmHg ( 3sig. figs.) 14.7psi c. The barometric pressure in Breckenridge, Colorado (elevation 9600 feet) is 580 mm Hg. How many atmospheres is this?  580mmHg  Modeling Chemistry 1atm  0.76atm 760mmHg 2 U2 ws 2 v3.0