CHEM 1A Lecture Notes - Ideal Gas Law, Gas Constant, Ideal Gas

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CHEM 1A Full Course Notes

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Gases - intro & review gas - particles move. Lower density than solids and liquids pressure = force / area or n / m^2. 1 atm = 760 mmhg = 101,325 pa. 825 mmhg ( 1 atm / 760 mmhg) = 1. 08 atm. 825 mmhg ( 101325 pa / 760 mmhg) = 1. 10 x 105 pa / 1000 = 1. 10 x 102 kpa ideal gas - molecules move randomly. Collisions are elastic, no energy is lost. Work well at low pressure and high temperatures. Boyle s law - assumes temperature and moles are constant. Increase in volume => decrease in pressure. P and v graph - curve // p and 1/v graph - straight positive slope line. Avogadro s law - relates moles to volume, as moles increase => volume increases, true when pressure and temperature are held constant. Charles law - relates temperature to volume and pressure. Temp increase => volume and pressure increase (constant pressure and volume)

Related Questions

To understand several methods of measuring gas pressure. Gases exert a measurable pressure (P) on the walls of their container. The SI unit for pressure is the pascal (Pa). Other pressure units frequently used in chemistry are millimeters of mercury (mmHg) and atmospheres (atm). You can convert between units of pressure using conversion factors such as those indicated below. 1 atm=760 mmHg=101,325 Pa

Part A

On a rainy day, a barometer reads 737 mmHg . Convert this value to atmospheres.

Express your answer numerically in atmospheres

Part B

A closed container is filled with oxygen. The pressure in the container is 445 kPa . What is the pressure in millimeters of mercury?

Express the pressure numerically in millimeters of mercury.

Part C

What is the pressure (in atmospheres) of the gas inside the container connected to an open-end, mercury-filled manometer as shown in the picture? (Figure 1) The atmospheric pressure is 0.95 atm.

Express your answer numerically in atmospheres.

Converting between Units of Pressure Gases are different from solids and liquids. In a sample of gas, the molecules are far apart. The gas molecules also move around and collide with each other as well as with the walls of the container. These collisions generate pressure. The pressure of a gas can be measured in different units. One convenient unit of measure is called the atmosphere (atm) because it is based on atmospheric pressure. At sea level, the average pressure is 1 atm. As you get higher in altitude, the pressure steadily drops until you leave the atmosphere, where the pressure is very close to 0 atm. The table below shows the different commonly used units of measuring gas pressure. Use this table in the pressure unit conversions. Unit Abbreviation 1 atm equivalent atmosphere atm 1.00 atm (exact) millimeters of mercury mmHg 760 mmHg torr torr 760 torr inches of mercury in.Hg 29.9 in.Hg pounds per square inch (psi) lb/in.2 14.7 lb/in.2 pascal Pa 101,325 Pa.

Part C

High-pressure liquid chromatography (HPLC) is a method used in chemistry and biochemistry to purify chemical substances. The pressures used in this procedure range from around 500 kilopascals (500,000 Pa) to about 60,000 kPa (60,000,000 Pa). It is often convenient to know the pressure in torr. If an HPLC procedure is running at a pressure of 5.81Ã10⁸ Pa , what is its running pressure in torr?

Express the pressure numerically in torr.

Question 11 pts

Which general statement about gases is NOT correct?

The molecules of a pure gas are distributed evenly throughout the container.

Gases are much less dense than liquids or solids

Molecules in a gas mixture can form layers according to their densities

Gases can be compressed, even to the point of liquefaction

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Question 21 pts

Which example is the greatest pressure?

1.00 atm

101 kPa

760 mm Hg (= 760 torr)

All of the above pressures are equal.

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Question 31 pts

Which example is the greatest pressure?

850 mm Hg (= 850 torr)

1.5 atm

All of the above pressures are equal.

96 kPa

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Question 41 pts

Assuming all other variables are held constant, a graph of which of the following will NOT yield a straight line?

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Question 51 pts

A sealed vessel contains 0.250 mol of oxygen gas. Which of the following will result in a decrease in the pressure of the oxygen gas?

increasing the number of moles of oxygen

increasing the temperature of the vessel

increasing the volume of the vessel

adding some helium to the vessel

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Question 61 pts

According to Charlesâs law, which change will cause the pressure of a gas to double? Pressure and amount of gas are constant.

The temperature decreases from 650 K to 325 K.

The temperature of the sample decreases fromï¿½88 Â°C to 44 Â°C.

The temperature of the sample increases fromï¿½22 Â°C to 44 Â°C.

The temperature of the sample increases fromï¿½250 K to 500 K.

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Question 71 pts

Which set of units for P, V, and T can be used for combined gas law calculations?

torr, L, and Kelvins

tm, g/L, and Kelvins

atm, mL, and degrees Celsius

inches of mercury, g/mL, and degrees Celsius

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Question 81 pts

The vapor pressure of a gas is

the atmospheric pressure at which the boiling point is determined.

the pressure at a Kelvin temperature exactly two times the boiling point.

impossible to determine experimentally without knowing the temperature and volume.

the pressure above a gas sample when evaporation and condensation are balanced.

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Question 91 pts

In a chemistry experiment where CO2 is collected over water, the atmospheric pressure is 755 mm. The partial pressure of water at the temperature in the lab is 24.2 mm. What is the pressure of the CO2?

779 mm

731 mm

More information is needed to answer this question

755 mm

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Question 101 pts

Which statement is NOT true according to the kinetic molecular theory of gases?

Molecules undergo elastic collisions

Molecules move in straight-line paths.

Molecules of different gases have differentï¿½kinetic energies at the same temperature

Molecules occupy a negligible volume.

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