Ch 5: Gases & Gas Laws

Question 1

Define: diffusion

Answer 1

The process of a gas expanding and mixing with other gases to fill an available space

Question 2

What is the general makeup of air on earth?

Answer 2

78% nitrogen
21% oxygen
1% argon
3-4% water vapor, CO2, sulfur dioxide, other

Question 3

What are the three main characteristics of gases?

Answer 3

• no specific form
• no specific volume
• expand to fill container

Question 4

Define: kinetic energy

Answer 4

energy that a body possesses by virtue of being in motion.

Question 5

What is the formula used to find the kinetic energy of a gas in a container?

Answer 5

Kinetic energy = 1/2M * (V*V)

Question 6

What does Graham’s Law find and what is the equation?

Answer 6

Gas effusion (leaking from a container) rate is inversely proportional to the square root of the mad of its particles.

r1/r2 = sq rt M1/M2

R = rate of effusion for 1st & 2nd gas (mol/unit time)
M = molar mass of 1st and 2nd gas

Question 7

What is atmospheric pressure (atm)?

Answer 7

Equal to the weight of air per unit area

Question 8

What is the difference between a barometer and a manometer?

Answer 8

Barometer measures atmospheric pressure (air pressure outside), manometer measures air pressure inside a container.

Question 9

What is Boyle’s Law?

Answer 9

When temp is constant, a volume of gas is inversely proportional to the pressure

P of i * V of i = P of f * V of f

i = initial state
f = final state
P = pressure
V = volume

Question 10

What is Charles’s law?

Answer 10

Effect of temp on gas. A heated mass of gas will gain Kinetic energy/velocity proportional to the heat added.

V of i % T of i = V of f % T of f
i = initial state
f = final state
V = velocity
T = temp in kelvin

Question 11

What is Gay-Lussac’s law?

Answer 11

As temp and kinetic energy/velocity increase, pressure increases.

P of i % T of i = P of f % T of f
Pf = Pi * Tf%Ti OR Tf = Ti * Pf%Pi
i = initial state
f = final state
P = pressure
T = temp in kelvin

Question 12

How to you convert degrees C to kelvin?

Answer 12

Add 273

Question 13

What is the combined gas law?

Answer 13

Method for finding the temp, volume or pressure of any gas.

P of i * V of i % T of i = P of f * V of f % T of f
i = initial state
f = final state
P = pressure
T = temp kelvin
V = volume

Question 14

What is Avogadro’s law?

Answer 14

When equal volumes of gases under the same pressure and temp will have equal numbers of molecules

V of i % n of i = V of f % n of f
i = initial state
f = final state
V = volume
n = # of molecules

Question 15

What is Avogadro’s number?

Answer 15

A constant number of atoms, ions or molecules in a sample. Equal to # of atoms in 12g of carbon-12 or 6.022 * 10 to the 23rd.

Question 16

What is the Ideal Gas Law?

Answer 16

Combination of Boyle’s, Charles’s, Gay-Lusac’s and Avogardo’s laws.

P * V = n * R * T

P = pressure (atm, torr, mm Hg, Pa, psi)
V = volume (liters, milliliters, ect)
n = # of molecules/moles of gas @ constant pressure and temp)
R = ideal gas constant, 0.0821 L atm%K mol
T = temp in kelvin

Question 17

What does STP stand for when dealing with chemistry?

Answer 17

Standard temp and pressure.