Chapter 4: Textbook Flashcards
How is force affected when exerted on a larger area?
The pressure is lower
How is force affected when exerted on a smaller area?
The pressure is higher
What is pressure?
The force per unit area
What kind of force is measured by gases?
The force exerted by moving molecules as they collide with objects in the path, particularly the walls of their container
What is the unit for pressure?
(Pa) Pascals
What is force measured in?
(N) Newtons
What does one Pascal measure?
The force of 1 N on an area of 1 Meter squared. 1 Pa = 1 N/m2
What is atmospheric pressure and the pressure of other gasses measured in?
Kilopascals (kPa)
What is a kPa?
1000 Pa or 1kN/m2 exactly
What is atmospheric pressure?
The force per unit area exerted by air on all objects
What is the atmospheric pressure at sea level?
About 101 kPa or
101.325 kPa exactly
What basis do scientists use to describe one standard atmosphere ( 1 atm)?
The atmospheric pressure at sea level 101.325 kPa
What were the previous standards for work with gases?
A temperature of 0 and a pressure of 1 atm/101.325 kPa
What conditions were known as Standard Temperature and Pressure (STP)?
0 degrees and 1 atm/101.325 kPa
What is the new standard for reporting the properties of substances called?
Standard Ambient Temperature and Pressure (SATP)
What are the definitions of Standard Ambient Temperature and Pressure (SATP)?
25 degrees and 100 kPa
How did Evangelista Torricelli accidentally invent a way for measuring atmospheric pressure?
He flipped over a glass tube filled with mercury into a tub filled with mercury and noticed how the mercury level change from day to day. This was called a Mercury Barometer
What did standard pressure used to be defined as?
760 Torr or 760mm Hg in honor Torricelli
What is 760 mm Hg equal to?
1 atm or 101.325 kPa
What happens to gases as pressure increases?
Their volume decreses
What happens to gases as pressure decreases?
The volume decreases
What is the mathematical equations to represent Pressure and volume in gases?
PV = k
What is Boyle’s Law?
As pressure on a gas increases, the volume of gas decreases proportionally, provided the temperature and chemical amount of gas remains constant
What is the equation to represent Boyle’s law?
P1 x V1 = P2 x V2
So basically PV = A constant
What did Jacques Charles discover?
The relationship between temperature and volume of gas
What is absolute 0?
0 Kelvins = -273 The lowest possible temperature
What is the basis for the Absolute or Kelvin temperature Scale?
Absolute 0
How do convert Celcius to Kelvin?
You add 273
What is the STP for Kelvin?
273.15 Kelvin
What is the SATP for Kelvin?
298.15 Kelvin
What is the boiling point of water in Kelvin?
273 K
What is the freezing point of water in Kelvin?
273 K
What is Charles law?
As the temperature of a gas increases, the volume of the gas increases proportionally, provided that the pressure and chemical amount of gas remain constant
What is the mathematical relationship the represents Charles law?
V1/T1 = V2/T2
so basically V/T = a constant
What are thermocouples best for?
High temperatures such as ovens
What are thermistors best suited for?
Low temperatures such as the home
What is the combined gas law?
The product of the pressure and volume of a gas sample is proportional to its absolute temperature in Kelvin.
What is the equation for the combined gas law?
PV/T= A constant (k) which means k is a constant as long as the amount of gas does not change
What does kinetic molecular theory explain?
Why gases, unlike solids and liquids, are compressible
Describe kinetic molecular theory as it pertains to solid, liquids and gas?
In solids the distance between its molecules are about the same size of it molecules. In liquids the spaces are slightly greater. In gases the distances are about 20 - 30 times greater.
If most of the volume of gases are empty space then it should be possible to force the molecules together
How will gases be affected if a volume of a container is reduced?
Gas molecules will move a shorter distance before colliding with the walls of a container. Since they collide with the walls more frequently, there will be increased pressure on the container
What is the pressure of gas relating to its container?
Basically pressure exerted by a gas is the total force of the collisions between the gas molecules and the walls distributed over an area of the container wall.
How does kinetic Molecular theory explain Charles law?
An increase in temperature represents an increase in average kinetic energy and therefore the average speed of the entities’ motion. In a container where pressure can be kept constant, faster moving molecules with collide more frequently with container walls. Thus the volume of gas increases with temperature
What is the law of combining volumes/Gay-Lussac’s law?
When measures at the same temperature and pressure, volumes of gaseous reactants and products of chemical reactions are always in simple ratios of whole numbers
What was Avogadro’s Theory?
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules
What is Molar Volume?
The volume that one mole of gas occupies at a specified temperature and pressure. That means molar volume is the same for all gases at the same temperature and pressure
What is the molar volume of gas at SATP?
24.8 L/mol
What is the molar volume of gas at STP?
22.4 L/mol
What is the symbol for molar volume?
Vm
What is an ideal gas?
A hypothetical gas that obeys all the gas laws perfectly under all conditions. It does not condense into liquid when cooled. And graphs of it are perfectly straight lines
What are the assumptions for ideal gasses?
- The gas molecules are very far apart, so their size is negligible
- They are in constant, random straight line motion
- they go through collisions in which no energy is lost
What is the equation for the ideal gas law?
PV = nRT
