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Do Now: Reading on Edmodo Complete guided notes chart – column 1. Atmospheric Pressure. Atmospheric pressure. The pressure of the atmosphere is ~100kPa which is 1atm. The conversion is: 1atm = 101.3kPa Pressure is measured by a barometer (a device that measures atmospheric pressure).
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Do Now: Reading on EdmodoComplete guided notes chart – column 1
Atmospheric pressure • The pressure of the atmosphere is ~100kPa which is 1atm. • The conversion is: 1atm = 101.3kPa • Pressure is measured by a barometer(a device that measures atmospheric pressure)
A device filled with mercury in a glass column (barometer) • At atmospheric pressure (1atm) The height of the Hg is 760mm • So… 1atm = 760mmHg
Do now: prepare for Pressure quizlet!!!Today’s Topic:Pressure-volume Behavior of Gases(Boyle’s Law)
Pressure-volume behavior of gases • Remember pushing on the syringe… you were able to compress the gas when you applied an outside pressure. • The more pressure applied….
As the volume became smaller, the gas particles collided more and increased the pressure. • Gas molecules are in constant random motion; gas pressure is caused by molecules colliding with the walls of the container.
Look at the following images… what is the relationship? Inversely Proportional!
Boyle’s law • Robert Boyle, English scientist studied gases. • Boyle’s Law – the pressure and volume of a gas sample at constant temperature are inversely proportional. P1V1 = P2V2
Sample problem • A weather balloon with a volume of 4200 L at 1.0 atm is tested by placing it in a chamber and decreasing external pressure to 0.72 atm. What will be the final volume of the balloon? • P1 = • V1 = • P2 = • V2 =
1. You buy helium gas in small pressurized cans to inflate party balloons. The can label indicates that the container delivers 7100 mL of helium gas at 100.0-kPa pressure. The volume of the gas container is 492 mL. • Do you think that the initial pressure of helium gas inside the can before use is greater or less than 100.0 kPa? Explain. • Calculate the initial pressure of helium gas inside the container. • Was your prediction in Question 1a correct?
2. Two glass bulbs are separated by a closed valve (see Figure 2.14). The 0.50-L bulb on the left contains a gas sample at a pressure of 6.0 atm. The 1.7-L bulb on the right is evacuated; it contains no gas: • Predict, in general, what will happen to the total volume of the gas sample if you open the middle valve. Explain. • Predict, in general, what will happen to the total pressure of the gas sample if you open the middle valve. Explain. • Calculate the actual pressure of the gas sample after the valve is opened.