Chemistry Flashcards
Which of the following correctly reflects the relationship between the volume and the external pressure on a gas at constant temperature?
- As pressure decreases, volume will increase.
2. Pressure and volume are inversely prepositional.
How does a gas exert pressure?
The moving gas particles strike each other and the wall of the container, exerting a force.
Pressure =
Force/Area
The SI unit for pressure is?
The Pascal (pa)
Boyles Law?
states the at constant temperature, the volume occupied by a fixed amount of gas is inversely promotional to the applied pressure. This means that as the pressure on the gas increases, the volume will decrease.
Pressure decreases with ?
Altitude
Manometers
Used to measure the pressure of a gas in an experiment
Barometer
Uses Mercury to measure atmospheric pressure = 760mmHg.
Invented by Torricelli
Closed-end Manometer
a mercury-filled, curved tube is closed at one end and attached to a flask at the other. When the flask is evacuated, the mercury levels in the two arms of the tube are the same because no gas exerts pressure on either mercury surface. When a gas is in the flask, it pushes down the mercury level in the near arm, causing the level to rise in the far arm. The difference in column heights (Δh) equals the gas pressure.
Open-end Manometer
also consists of a curved tube filled with mercury, but one end of the tube is open to the atmosphere and the other is connected to the gas sample. The atmosphere pushes on one mercury surface, and the gas pushes on the other. Again, Δh equals the difference between two pressures. But, when using this type of manometer, we must measure the atmospheric pressure with a barometer and either add or subtract Δh from that value.
1 atm=
760 mmHg
1 torr=
1 mmHg
1 atm=
101.325 kPa
Charles’s Law
at constant pressure, the volume occupied by a fixed amount of gas is directly proportional to its absolute (Kelvin) temperature
Volume of 1 mole of an ideal gas at STP?
22.4L
0 Kelvin is equal to what C
-273.15 C
Avagadro’s Law
at fixed temperature and pressure, equal volumes of any ideal gas contain equal numbers (or moles) of particles.
STP
0C (273.15K) 1 atm (760 torr)
R the universal gas constant is equal to
0.0821 atm . L/ mol . K
Thermodynamics
the study of energy and its transformation
Thermochemistry
is a branch of thermodynamics that deals with the heat involved in chemical and physical changes.
1st Law of Thermodynamics
states that the total
energy of the universe is constant.
Esystem=-Euniverse
Units of Energy
J
Density of a gas
mass/volume
(O2: 32g/22.4L=1.43g/L
What is moles = to
mass/Molar mass
Pv=(m/M)RT
d=P(M)/RT
The density of a gas is ____ _____ to the temperature
Inversely Proportional
The density of a gas is ____ _____ to the pressure
directly proportional
An alternative approach for finding the density of most simple gases, but at STP only, is to divide the molar mass by the standard molar volume, 22.4 L:
d=m/v
Through another rearrangement of the ideal gas law, we can determine the molar mass of an unknown gas or a volatile liquid (one that is easily vaporized):
M=mRT/PV
in a mixture of unreacting gases, the total pressure is the sum of the partial pressures of the individual gases:
Daltons Law of partial pressure
Mole Fractions
Mole of N2/Total amount mole
nN2/nN2 + nH2 (mole fractions for N2 and H2
If the total pressure is due to the total number of moles, the partial pressure of gas A is the total pressure multiplied by the _____?
Mole fraction
Kinetic Molecular Theory
Postulate 1
Particle volume. A gas consists of a large collection of individual particles with empty space between them. The volume of each particle is so small compared with the volume of the whole sample that it is assumed to be zero; each particle is essentially a point of mass.
Kinetic Molecular Theory
Postulate 2
Particle motion. The particles are in constant, random, straight-line motion, except when they collide with the container walls or with each other.
Kinetic Molecular Theory
Postulate 3
Particle collisions. The collisions are elastic, which means that, like minute billiard balls on a frictionless billiards table, the colliding molecules exchange energy but do not lose any energy through friction. Thus, their total kinetic energy (Ek) is constant. Between collisions, the molecules do not influence each other by attractive or repulsive forces.
Distribution of molecular speeds at 3 temperatures
- the curves flatten and spread at higher temperatures
- the most probable speed (the peak of each curve) increases as the temperature increases.
Mean free path of a gas particle
The average distance a gas particle travels between collisions (either with other particles or the wall)
Diffusion
the movement of one gas through another
Effusion
process of a gas escaping through a tiny hole
Change in internal E
∆E= E Final-E initial ∆E= E products - E reactants
By releasing some energy in a transfer to the surroundings
E final < E initial
By absorbing some energy in a transfer from the surroundings
E initial < E final
∆E = q + w
The total change in a system’s internal energy is the sum of the energy transferred as heat and/or as work:
Positive Energy
Energy transferred into the system is positive because the system ends up with more energy.
Negative Energy
Energy transferred out from the system is negative, because the system ends up with less energy.
For a system that transfers energy only as heat (q) and does no work (w = 0), we have
∆E = q
For a system that transfers energy only as work, q = 0
∆E = w
A _____ function is path independent, meaning that only the ____ and ____ conditions are needed to measure the net change that occurred.
state
initial
Final
A change in ∆H (enthalpy) is equal to the change in heat (q) when the system is at constant ______.
Pressure
All common Sulfates soluble except
CaSO4, SrSO4, BaSO4, AgSO4, PbSO4
All common fluorides soluble except
PbF2, Flourides of group 2A
All common Chlorides, bromides, and Iodides soluble excpet
Ag+, Pb2+, Cu+, Hg22+
All common Nitrates, acetates, and percholrates soluble
no exceptions
NO3-, CH3C00-, CLO4-
All common compounds of Group 1A soluble
no exceptions
All common metal hydroxides are insoluble except
Group 1A hydroxides, Ca(OH)2, Sr(OH)2, and Ba(OH)2
All common carbonates (CO2-3) and phosphates (PO34-) are insoluble except
carbonates and phosphates of Group 1A, and NH4+
All common sulfides are insoluble except
Sulfides of Group 1A, and NH4+
