Gases, liquids, and solids Flashcards
Name some general gases and how they appear in the world
- surrounded by an atmosphere composed of a mixture of gases: air (78% N2 and 21% O2)
- Oxygen (O2) supports human life, chlorine gas (Cl2) is used to purify drinking water, acetylene gas (C2H2) is used in welding (Schweißen), carbon dioxide (CO2) and methane (CH4) are implicated in global warming
Name some properties of gases
- Many molecular compounds are gases
- All gases are composed entirely of nonmetallic elements.
- All gases have simple molecular formulas and low molar masses.
- A gas expands spontaneously to fill its container.
- The volume of a gas equals the volume of its container.
- Gases are highly compressible: upon pressure their volume decreases.
- Gases form homogenous mixtures with each other regardless of the identities orrelative proportions of the component gases.
(ex: water and gasoline vapor and liquid mixtures) - The characteristic properties of the gases arise because the individual molecules are relatively far apart.
- As a result, different gases behave similarly.
P=?
F=?
- Pressure, P, is the force, F, that acts on a given area, A:
- P = F / A
- Force: F = ma
How can the atmospheric pressure be measured?
-by use of a mercurey barometer
What do you know about the Standard atmospheric pressure?
-Standard atmospheric pressure, which corresponds :to the typical pressure at sea level, is the pressure sufficient to support :a column of mercury 760 mm in height
How do you calculate the pressure of a gas ( closed end)
-Pgas= Ph1
How do you calculate the pressure of a gas ( open end) if gas is moved to left?
-Pgas + Ph2= Pate (760mm hg)
How do you calculate the pressure of a gas ( open end) if gas is moved to right?
-Pgas =Ph2+ Pate (760mm hg)
How much torr is one pa? How much pa is one bar?
- 1 torr =133.322Pa
- 1pa= 0.00001bar
What does the Boyle’s Las say?
- The Pressure-Volume Relationship
- The volume of a fixed quantity of gas maintained at constant temperature is inversely proportional to the pressure
- > the more pressure the less volume (anti-proportional in Vp diagramm)
What does the Charles’s Law say?
- The Temperature-Volume Relationship
- The volume of a fixed amount of gas maintained at constant pressure is directly proportional to its absolute temperature
- > the higher the temperature the bigger the volume
What does the Avogadro’s Law say?
-The Quantity-Volume Relationship
-The volume of a gas maintained at constant temperature and pressure is directly proportional to the number of moles of the gas:
V = constant x n
What was Gay-Lussac’s observation and Avogadro’s explanation?
- observation: two volumes’ hydrogen one volume oxygen result two volumes water vapor (Wasserdampf)
- explanation: 2H2(g) + O2(g) ->2H2O (g)
What is the ideal gas equation?
- PV = nRT
- an ideal gas is a hypothetical gas whose pressure, volume, and temperature behavior is completely described by the ideal-gas equation.
- The term R is called the gas constant.
- Temperature must always be expressed in K!
Does the ideal gas equation accurately describe real gases?
- The ideal gas equation does not always accurately describe real gases
- Ordinarily, the difference btw ideal and real behavior is so small that we may ignore it
What is dalton describing`?
- Total pressure of a mixture of gases equals the sum of the pressures that each would exert if it were present alone
- Pt = P1 + P2 + P3 + …
Why is it the case with the Delton’s law?
-each gas in a mixture behaves independently, we can easily relate the amount of a given gas in a mixture to its partial pressure
What are the five rules of Kinetic-Molecular Theory?
-gases consist of large numbers of molecules
that are in continuous, random motion.
-The volume of all the molecules of the gas is negligible compared to the total volume in which the gas is contained
-Attractive and repulsive forces btw gas molecules are negligible
-Energy can be transferred btw molecules during collisions, but the average kinetic energy of the molecules do not change with time
-The average kinetic energy of the molecules is proportional to the absolute temperature. At any given temperature the molecules of all gases have the same average kinetic energy